We are running multiple schools on ground source heat pumps. Each
building has a single loop with individual Trane heat pumps
running in each classroom tapped onto that loop. There is NO
auxiliary heat. There are NO heat strips. Our Energy Czar
believes in night set backs and holding temperatures at minimums
until someone gripes. The systems are computerized to central
control and the units can only be changed from the central
location other than a small allowance at the thermostats.

Each building, or even portions of buildings, have different
thermal mass/draft and air leakage issues/poor glazing/etc that
each requires its own start up time. Some take 2 hours, some
almost 4 hours if they have been allowed to get too far out of
design or conditions are extreme. The water loop is circulated
full time through the well field, but the compressors at each heat
pump function by thermostat. The buildings have become so much
easier to control that we continue to install these systems as
money permits. The buildings are so much more stable that we tend
to ignore old fashioned insulation/draft/weatherstrip conditions -
perhaps we will get back to them as energy costs continue to
spiral.

Our HVAC technicians would prefer just letting the systems run
full time and maintain a steady temperature, especially when
equipment is new just to run it through its paces while under
warranty. The Energy Czar tends to win. I will try to remember
to ask tomorrow about the whys.

Each well field happens to have hit multiple water tables, so each
field is way under capacity as they are originally designed on the
assumption of no significant water zones and rely on ground
contact through the custom gel only. We have two sites without
well fields that run the loop through a cooling tower (no chiller)
and small redundant boilers with plate frame exchangers. These
were the first 2 sites when too many folks were afraid of the
ground source. Who knows on a 20 to 50 year cycle, but right now
groundsource is far and away the most efficient, cleanest, lowest
maintenance system out there. We're not walking, we're running!

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"J. Clarke" wrote in message
...
Kenneth wrote:
On Tue, 27 Nov 2007 11:31:32 -0500, "J. Clarke"
wrote:

But the time at lower setpoint more than compensates for the
differential loss. It's well-established in general that a
setback
lowers overall heating costs in general. It would take
unusual
circumstances for that to not be so.

It's not something one should just assume. Especially with
alternative energy.

Hi John,

Might you know of some reasons that the general principle of
savings through setbacks would not apply to my geothermal
source...?

As I have said before here, I certainly do not (know enough
to) disagree, but I have no understanding of why that should
be true.

Sincere thanks,

I don't know enough details of your setup or the structure to be
able
to run the numbers. The main objection I'm seeing is that it's
likely
to cause the resistance elements in the heat pump to kick in but
you
say that you don't have any, but there might be something else
unique
to your situation.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

On Tue, 27 Nov 2007 18:56:19 -0500, Jim Behning
wrote:


Why do you need a second electric meter to excrement with? You can
read your own meter every day at the same time. As long as you record
when you are drying clothes or other significant electricity burning
events you should be able to test for no hardware costs.

Are you torturing the group by not doing your own meter reading and
reporting back?

Hi Jim,

I am lost...

How would reading my meter at the same time every day tell
me my heat-related energy consumption?

Thanks,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Wed, 28 Nov 2007 09:46:22 -0500, Kenneth
wrote:

On Tue, 27 Nov 2007 18:56:19 -0500, Jim Behning
wrote:


Why do you need a second electric meter to excrement with? You can
read your own meter every day at the same time. As long as you record
when you are drying clothes or other significant electricity burning
events you should be able to test for no hardware costs.

Are you torturing the group by not doing your own meter reading and
reporting back?

Hi Jim,

I am lost...

How would reading my meter at the same time every day tell
me my heat-related energy consumption?

Thanks,
Day zero meter reads 1480
Day one with no thermostat changes reads 1520
Day two no thermostat change 1570
day 3 no thermostat change 1620
Day 4 after thermostat rollback 1680
day 5 with thermostat rollback 1740
day6 with thermostat rollback 1800
day 7 no thermostat change 1850
day 8 thermostat rollback 1910
day 9 thermostat rollback 1970
day 10 no thermostat change 2020

and so on. Just read the meter every day at the same time. Do the
math. Do it over enough days to factor out clothes dryers and baking
festivals. If there is indeed any significant energy saving to be had
by thermostat rollback it will show up with a month of measuring.
Especially if you do rollback every other night.

That said I think when I feel rich I will buy
http://www.theenergydetective.com/store or one of these with the split
core
http://eyomenergy.com/Merchant2/merc...gory_C ode=ES

On Wed, 28 Nov 2007 18:56:46 -0500, Jim Behning
wrote:

On Wed, 28 Nov 2007 09:46:22 -0500, Kenneth
wrote:

On Tue, 27 Nov 2007 18:56:19 -0500, Jim Behning
wrote:


Why do you need a second electric meter to excrement with? You can
read your own meter every day at the same time. As long as you record
when you are drying clothes or other significant electricity burning
events you should be able to test for no hardware costs.

Are you torturing the group by not doing your own meter reading and
reporting back?

Hi Jim,

I am lost...

How would reading my meter at the same time every day tell
me my heat-related energy consumption?

Thanks,
Day zero meter reads 1480
Day one with no thermostat changes reads 1520
Day two no thermostat change 1570
day 3 no thermostat change 1620
Day 4 after thermostat rollback 1680
day 5 with thermostat rollback 1740
day6 with thermostat rollback 1800
day 7 no thermostat change 1850
day 8 thermostat rollback 1910
day 9 thermostat rollback 1970
day 10 no thermostat change 2020

and so on. Just read the meter every day at the same time. Do the
math. Do it over enough days to factor out clothes dryers and baking
festivals. If there is indeed any significant energy saving to be had
by thermostat rollback it will show up with a month of measuring.
Especially if you do rollback every other night.

That said I think when I feel rich I will buy
http://www.theenergydetective.com/store or one of these with the split
core
http://eyomenergy.com/Merchant2/merc...gory_C ode=ES

You are not measuring how much you spend on heating, you are measuring
much less or more you are spending by trying different thermostat
strategies. You also need to note wind, sunshine and outside temp. My
heat does not run on a 50 degree day with sun and little to no wind.

Jim Behning wrote:
On Wed, 28 Nov 2007 18:56:46 -0500, Jim Behning
wrote:

On Wed, 28 Nov 2007 09:46:22 -0500, Kenneth
wrote:

On Tue, 27 Nov 2007 18:56:19 -0500, Jim Behning
wrote:


Why do you need a second electric meter to excrement with? You
can
read your own meter every day at the same time. As long as you
record when you are drying clothes or other significant
electricity burning events you should be able to test for no
hardware costs.

Are you torturing the group by not doing your own meter reading
and
reporting back?

Hi Jim,

I am lost...

How would reading my meter at the same time every day tell
me my heat-related energy consumption?

Thanks,
Day zero meter reads 1480
Day one with no thermostat changes reads 1520
Day two no thermostat change 1570
day 3 no thermostat change 1620
Day 4 after thermostat rollback 1680
day 5 with thermostat rollback 1740
day6 with thermostat rollback 1800
day 7 no thermostat change 1850
day 8 thermostat rollback 1910
day 9 thermostat rollback 1970
day 10 no thermostat change 2020

and so on. Just read the meter every day at the same time. Do the
math. Do it over enough days to factor out clothes dryers and
baking
festivals. If there is indeed any significant energy saving to be
had
by thermostat rollback it will show up with a month of measuring.
Especially if you do rollback every other night.

That said I think when I feel rich I will buy
http://www.theenergydetective.com/store or one of these with the
split core
http://eyomenergy.com/Merchant2/merc...gory_C ode=ES

You are not measuring how much you spend on heating, you are
measuring
much less or more you are spending by trying different thermostat
strategies. You also need to note wind, sunshine and outside temp.
My
heat does not run on a 50 degree day with sun and little to no wind.

Just for some perspective, last week the temperature here was 60
degrees, which melted the snow that had come down a couple of days
previously.
--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

Kenneth wrote:

[...asking about setback and subject...]

Don't know if you gave up or got an answer but I mentioned the OSU site
earlier. Being bored, I went and found it -- here's the current link.
Didn't find a specific answer in the faq's, but they have a couple of
contact ways you can get to them.

http://www.igshpa.okstate.edu/index.htm


hth...

--

Kenneth wrote:


Howdy,

This is way OT...(again), but:

We heat and cool our home geothermally (water to air
system.)

We would, of course, like to decrease our costs further if
we can, and so have explored the benefits of setting our
thermostat lower at those times when the house (or parts of
it) are not occupied.

The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged.

Of course, I have asked "why", but when I do, it seems that
smoke starts to come out of the phone. In essence, they say
that it is "best" but seem unable to say why.

Might any of you know what would be best in this regard ,
and particularly whether the issue of thermostat setback is
actually any different for geothermal systems?

Sincere thanks,


hi all!

i sent this email to Alliant Energy Geothermal
===============
there is a discussion underway with this as topic: -
We heat and cool our home geothermally (water to air system.) We
would, of course, like to decrease our costs further if we can, and so
have explored the benefits of setting our thermostat lower at those
times when the house (or parts of it) are not occupied. The folks who
designed the heating system say that with these systems, it is best to
leave the set temp unchanged. Of course, I have asked "why", but when I
do, it seems that smoke starts to come out of the phone. In essence,
they say that it is "best" but seem unable to say why. Might any of you
know what would be best in this regard , and particularly whether the
issue of thermostat setback is actually any different for geothermal
systems?
could you help me understand the issues involved? thanks in advance
for any input! chuck b:-)
==============
and i got this reply
-----------------------

Dear Chuck,

Set-up of a Geo system temperature during the cooling time of year
should allow a Geo system to recover the cooling and dehumidify as
quickly and more efficiently than other air sourced cooling systems.

Set-back is not typically recommended during the heating time of year
due to 1) a slower recovery time for heating, 2) the potential for the
back up electric elements kicking in to boost the reheating rate but, at
an added electric expense to you, 3) dependent on if you use a straight
well water open loop or only a minimal to non freeze protected closed
loop fluid, the lack of normal flows may allow for a potential for a
loop to freeze up and 4) many people who own set-back thermostats are
easily confused by the instructions for operating them and re-setting them.

All of these can cause contractor callbacks, they hate callbacks.

We do have a few of our regional Geo system owners who do a slight
setback for heating at maybe 2 to 4 degrees F maximum for 4 to 6 hours
but, all must realize the potential results.

During AC season and the daytime hours of unoccupied homes, they might
also do set up to minimize On Peak energy charges when they choose Time
of Use electric rate options.

I hope this helps. Thanks for the inquiry.

Leo

From: Alliant Energy Geothermal Web Forms
]
Sent: Wednesday, November 28, 2007 9:29 PM
To: Geothermal
Cc: Webmaster
Subject: Alliant Energy Geothermal -- Contact Us Form



chuck b:-)

On Fri, 30 Nov 2007 20:56:41 GMT, chuckb wrote:

Kenneth wrote:


Howdy,

This is way OT...(again), but:

We heat and cool our home geothermally (water to air
system.)

We would, of course, like to decrease our costs further if
we can, and so have explored the benefits of setting our
thermostat lower at those times when the house (or parts of
it) are not occupied.

The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged.

Of course, I have asked "why", but when I do, it seems that
smoke starts to come out of the phone. In essence, they say
that it is "best" but seem unable to say why.

Might any of you know what would be best in this regard ,
and particularly whether the issue of thermostat setback is
actually any different for geothermal systems?

Sincere thanks,


hi all!

i sent this email to Alliant Energy Geothermal
===============
there is a discussion underway with this as topic: -
We heat and cool our home geothermally (water to air system.) We
would, of course, like to decrease our costs further if we can, and so
have explored the benefits of setting our thermostat lower at those
times when the house (or parts of it) are not occupied. The folks who
designed the heating system say that with these systems, it is best to
leave the set temp unchanged. Of course, I have asked "why", but when I
do, it seems that smoke starts to come out of the phone. In essence,
they say that it is "best" but seem unable to say why. Might any of you
know what would be best in this regard , and particularly whether the
issue of thermostat setback is actually any different for geothermal
systems?
could you help me understand the issues involved? thanks in advance
for any input! chuck b:-)
==============
and i got this reply
-----------------------

Dear Chuck,

Set-up of a Geo system temperature during the cooling time of year
should allow a Geo system to recover the cooling and dehumidify as
quickly and more efficiently than other air sourced cooling systems.

Set-back is not typically recommended during the heating time of year
due to 1) a slower recovery time for heating, 2) the potential for the
back up electric elements kicking in to boost the reheating rate but, at
an added electric expense to you, 3) dependent on if you use a straight
well water open loop or only a minimal to non freeze protected closed
loop fluid, the lack of normal flows may allow for a potential for a
loop to freeze up and 4) many people who own set-back thermostats are
easily confused by the instructions for operating them and re-setting them.

All of these can cause contractor callbacks, they hate callbacks.

We do have a few of our regional Geo system owners who do a slight
setback for heating at maybe 2 to 4 degrees F maximum for 4 to 6 hours
but, all must realize the potential results.

During AC season and the daytime hours of unoccupied homes, they might
also do set up to minimize On Peak energy charges when they choose Time
of Use electric rate options.

I hope this helps. Thanks for the inquiry.

Leo

From: Alliant Energy Geothermal Web Forms
]
Sent: Wednesday, November 28, 2007 9:29 PM
To: Geothermal
Cc: Webmaster
Subject: Alliant Energy Geothermal -- Contact Us Form



chuck b:-)
Now that has a few good answers. I would not have thought about the
freezing closed loops.

On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
wrote:

Now that has a few good answers. I would not have thought about the
freezing closed loops.

Howdy,

Any responsibly designed system protects against such
freezing...

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Kenneth wrote:
On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
wrote:

Now that has a few good answers. I would not have thought about the
freezing closed loops.
....
Any responsibly designed system protects against such
freezing...

....

My thinking precisely. The response basically is a bunch of
weasel-words. The upshot basically is if the aux heat issue is taken
care of properly and one doesn't mind the recovery time, setback will
save. For a reasonable source capacity, our experience was that while
the outlet temperatures aren't equivalent to gas, they're sufficiently
high the air feels "warm enough" circulating as opposed to the and as
compared to air-air heat pump that felt cool...

If there's freeze-up w/ a few degrees setback so the unit runs a little
less at night, there's going to be freeze up on other days as well...

--

chuckb wrote:
Kenneth wrote:

On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
wrote:


Now that has a few good answers. I would not have thought about the
freezing closed loops.


Howdy,

Any responsibly designed system protects against such
freezing...

All the best,


but on the other hand:

from your OP
"The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged."

any system that is operated outside it's design criteria risks failure!
...

A few degrees lower is "outside the design" for a residential hvac
system? I still think there's been no rational basis for the
proscription given unless, as Ken says, there's a problem--and if
there's a problem, I think there will be a problem irrespective of the
setback.

--

Kenneth wrote:

On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
wrote:


Now that has a few good answers. I would not have thought about the
freezing closed loops.


Howdy,

Any responsibly designed system protects against such
freezing...

All the best,


but on the other hand:

from your OP
"The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged."

any system that is operated outside it's design criteria risks failure!

good luck with yours!

chuck b:-)

chuckb wrote:
dpb wrote:

chuckb wrote:

Kenneth wrote:

On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
wrote:


Now that has a few good answers. I would not have thought about the
freezing closed loops.



Howdy,

Any responsibly designed system protects against such
freezing...

All the best,



but on the other hand:

from your OP
"The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged."

any system that is operated outside it's design criteria risks failure!

..

A few degrees lower is "outside the design" for a residential hvac
system? I still think there's been no rational basis for the
proscription given unless, as Ken says, there's a problem--and if
there's a problem, I think there will be a problem irrespective of the
setback.

....
you seem to be reading things that i didn't say or if i did i certainly
did not mean to.. oh well, have a good day!

Well, what _did_ you mean, then???

--

dpb wrote:

chuckb wrote:

Kenneth wrote:

On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
wrote:


Now that has a few good answers. I would not have thought about the
freezing closed loops.



Howdy,

Any responsibly designed system protects against such
freezing...

All the best,



but on the other hand:

from your OP
"The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged."

any system that is operated outside it's design criteria risks failure!

..

A few degrees lower is "outside the design" for a residential hvac
system? I still think there's been no rational basis for the
proscription given unless, as Ken says, there's a problem--and if
there's a problem, I think there will be a problem irrespective of the
setback.

--


you seem to be reading things that i didn't say or if i did i certainly
did not mean to.. oh well, have a good day!

chuck b:-)

In article ,
Kenneth wrote:
On Tue, 27 Nov 2007 18:07:39 -0000,
(Robert Bonomi) wrote:


Hi Robert,

I thank you for your detailed response...

Perhaps I am not understanding what you have written, but
allow me to ask something further.

Please see my comments inline below:


I wrote:
If the internal temperature of the house is allowed to drop,
two things happen. First, there is the direct energy savings
because it takes fewer BTUs to keep the house at the lower
temp;

You responded:
_THOSE_ BTUs are just 'deferred spending'. you spend exactly
that amount to raise the temp back to the original setting.

I wrote:
but perhaps less obviously, the rate of heat loss to
the outside environment is decreased. (Because the greater
the temperature differential, the more rapid the rate of
equalization.)

You responded:
That is the -totality- of the energy savings -- the lowered losses.
from the reduced temperature.


In my attempt to understand this...

Suppose I lowered the temperature of the house 10 degrees,
but not merely overnight. Instead, I left them lower for a
month.

Would I not have very significant savings for that month?

Relative to what you would have 'spent' at the 10degree higher
temperature yes.

If so, would not the reasons for those savings apply as well
to my overnight lowering of the house's internal temperature
(though with decreased benefit because of the diminished
duration)?

Yes and no. grin

There are three intervals to consider.
1) while the temperature is falling from 'X' to 'X-10',
2) while the temperature is stable at 'X-10',
3) while the temperature is rising from 'X-10' to 'X'.

As the house cools from 'X' to 'X-10', you aren't providing any heat input
at that time. *THAT* 'savings', is cancelled by the 'extra' energy you
have to put back into the building the next day, to raise the temperature
from 'X-10' back to 'X'. For complicated reasons, it usually takes a little
more energy to go from 'X-10' to 'X' than was 'saved' by letting things
fall from 'X' to 'X-10'. This differential is usually fairly minor, however
it can be magnified if the -rates- at which the temperature falls and rises
are different.

The heat input required to maintain the house at a constant "X" is exactly
the heat losses being radiated by the house to the exterior.

The heat input required to maintain the house at a constant "X-10" is exactly
the heat losses being radiated by the house to the exterior.

In both cases the rate of loss is a function of (a) the temperature
differential, _and_ the quality of the insulation.

The point is, however, that the difference in heat input is exactly the
difference in thermal losses, at a constant temperature. You cannot count
a savings for less heat input, -and- a savings for lower thermal losses.

In article , DanG wrote:
We are running multiple schools on ground source heat pumps. Each
building has a single loop with individual Trane heat pumps
running in each classroom tapped onto that loop. There is NO
auxiliary heat. There are NO heat strips. Our Energy Czar
believes in night set backs and holding temperatures at minimums
until someone gripes. The systems are computerized to central
control and the units can only be changed from the central
location other than a small allowance at the thermostats.

Each building, or even portions of buildings, have different
thermal mass/draft and air leakage issues/poor glazing/etc that
each requires its own start up time. Some take 2 hours, some
almost 4 hours if they have been allowed to get too far out of
design or conditions are extreme. The water loop is circulated
full time through the well field, but the compressors at each heat
pump function by thermostat. The buildings have become so much
easier to control that we continue to install these systems as
money permits. The buildings are so much more stable that we tend
to ignore old fashioned insulation/draft/weatherstrip conditions -
perhaps we will get back to them as energy costs continue to
spiral.

Our HVAC technicians would prefer just letting the systems run
full time and maintain a steady temperature, especially when
equipment is new just to run it through its paces while under
warranty. The Energy Czar tends to win. I will try to remember
to ask tomorrow about the whys.

A 'medium-insulated' school building full of people doesn't need _any_
additional heat source until the outside temperature gets below about
-20F.

Look up how much heat an 'at rest' human body gives off, and multiply by
the 25-30 bodies preset in the average classroom.

Getting the heat _out_ of the building is the issue.

At 'above zero' temperatures, it's _common_ to be venting hot air outside
and pulling in cold outside air for 'make-up'.

Not infrequently, the chillers will be running, in addition.

Robert, as you said, bodies and lights make a huge load on a
building. Our Energy Czar (EC) lets the buildings get cold enough
that they typically require a morning warm up before the occupant
load takes over. We have one 2 pipe school that requires a full
conversion to either heat or cool that can be quite troublesome on
those moderate days. We turn all chillers off and dump the
cooling towers as we head into the freezing months. The buildings
can usually be tempered by outside air. The geothermal schools
eliminate this problem and allow partial usage of buildings for
special events and summer school type needs.

I did ask about the setback issues. We had one series of heat
pumps whose open/close valves did not have stops installed. These
machines have a sensor that says if the water is too cold it
prevents the unit from running rather than make ice - this issue
was rectified by installing stops that never allow the valves to
completely close which keeps the water circulating back to the
loop. We now install all systems to run the well field pumps
continuously as we have one that turns off the circulating pumps
if there is no demand anywhere on the system which can allow some
of the loop to reach that same "don't run" temperature. Believe
it or not, the pumps have shut down several times because the
building is that stable. As Robert says, lights and people can
keep a large building quite warm or too warm when the rest of us
need heat. We do continue to have a problem with people wanting
cooling on warm afternoons turning the thermostat down to the
bottom at 55°: the computer limits the units so the 55 never
happens, but the units also don't come up on morning warm-up,
though the rooms seem to recover quickly if the rest of the
building is satisfied. He swears emphatically that no matter what
system is used, intense run time in the mornings uses less energy
than the start/stop cycle of leaving the system at temperature
around the clock. They have put in-line monitors with recording
capability on units set up each way on highly similar usage, run
them for a week, then reversed the study for another week on the
same units. Setback with a substantial run time to recover uses
less energy than maintaining the temperature during non critical
times. The setback needs to be able to protect critical needs as
in not freezing water lines or baking cookies in the attic.


______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Robert Bonomi" wrote in message
...
In article , DanG
wrote:
We are running multiple schools on ground source heat pumps.
Each
building has a single loop with individual Trane heat pumps
running in each classroom tapped onto that loop. There is NO
auxiliary heat. There are NO heat strips. Our Energy Czar
believes in night set backs and holding temperatures at minimums
until someone gripes. The systems are computerized to central
control and the units can only be changed from the central
location other than a small allowance at the thermostats.

Each building, or even portions of buildings, have different
thermal mass/draft and air leakage issues/poor glazing/etc that
each requires its own start up time. Some take 2 hours, some
almost 4 hours if they have been allowed to get too far out of
design or conditions are extreme. The water loop is circulated
full time through the well field, but the compressors at each
heat
pump function by thermostat. The buildings have become so much
easier to control that we continue to install these systems as
money permits. The buildings are so much more stable that we
tend
to ignore old fashioned insulation/draft/weatherstrip
conditions -
perhaps we will get back to them as energy costs continue to
spiral.

Our HVAC technicians would prefer just letting the systems run
full time and maintain a steady temperature, especially when
equipment is new just to run it through its paces while under
warranty. The Energy Czar tends to win. I will try to remember
to ask tomorrow about the whys.

A 'medium-insulated' school building full of people doesn't need
_any_
additional heat source until the outside temperature gets below
about
-20F.

Look up how much heat an 'at rest' human body gives off, and
multiply by
the 25-30 bodies preset in the average classroom.

Getting the heat _out_ of the building is the issue.

At 'above zero' temperatures, it's _common_ to be venting hot
air outside
and pulling in cold outside air for 'make-up'.

Not infrequently, the chillers will be running, in addition.

Robert Bonomi wrote:

.... snip
Our HVAC technicians would prefer just letting the systems run
full time and maintain a steady temperature, especially when
equipment is new just to run it through its paces while under
warranty. The Energy Czar tends to win. I will try to remember
to ask tomorrow about the whys.

A 'medium-insulated' school building full of people doesn't need _any_
additional heat source until the outside temperature gets below about
-20F.

Look up how much heat an 'at rest' human body gives off, and multiply by
the 25-30 bodies preset in the average classroom.


From EDEE 101 (or Physics 112), we were told that the average human body
is equivalent to 100 watt light bulb as far as heat output. Depending upon
age, kids in a school would most likely be considerably less.


Getting the heat _out_ of the building is the issue.

At 'above zero' temperatures, it's _common_ to be venting hot air outside
and pulling in cold outside air for 'make-up'.

Not infrequently, the chillers will be running, in addition.

--
If you're going to be dumb, you better be tough

Mark & Juanita wrote in
:

From EDEE 101 (or Physics 112), we were told that the average human
body
is equivalent to 100 watt light bulb as far as heat output. Depending
upon age, kids in a school would most likely be considerably less.


You haven't seen my 11 year-old granddaughter - 250 Watt is more like it.

--
Best regards
Han
email address is invalid

In article ,
Mark & Juanita wrote:
Robert Bonomi wrote:

... snip
Our HVAC technicians would prefer just letting the systems run
full time and maintain a steady temperature, especially when
equipment is new just to run it through its paces while under
warranty. The Energy Czar tends to win. I will try to remember
to ask tomorrow about the whys.

A 'medium-insulated' school building full of people doesn't need _any_
additional heat source until the outside temperature gets below about
-20F.

Look up how much heat an 'at rest' human body gives off, and multiply by
the 25-30 bodies preset in the average classroom.


From EDEE 101 (or Physics 112), we were told that the average human body
is equivalent to 100 watt light bulb as far as heat output.

That's a bit on the low side -- about right for sleeping. 'resting' is more
in the 110-120 range. Circa 125 is frequently used for estimating purposes.

Call it 12,000 BTU/hr per room, plus another few thousand for the lighting.

Scale up by a factor of 4, for equivalent footage to a medium house,
and you've got the equivalent of an 80% efficient 150,000 BTU/hr furnace
running at a _50%_ duty cycle.

Depending upon
age, kids in a school would most likely be considerably less.

Surprisingly small differences. lower elementary ages are about 75-80% of
adult.

Getting the heat _out_ of the building is the issue.

At 'above zero' temperatures, it's _common_ to be venting hot air outside
and pulling in cold outside air for 'make-up'.

Not infrequently, the chillers will be running, in addition.

In article ,
Han wrote:
Mark & Juanita wrote in
:

From EDEE 101 (or Physics 112), we were told that the average human
body
is equivalent to 100 watt light bulb as far as heat output. Depending
upon age, kids in a school would most likely be considerably less.


You haven't seen my 11 year-old granddaughter - 250 Watt is more like it.

Depending on activity level, you can _triple_ (or somewhat more) the base
number, which is in the 100-140 watt range.

A 250 watt kid is -not- all that extreme! grin

(Robert Bonomi) wrote in
:

In article ,
Han wrote:
Mark & Juanita wrote in
:

From EDEE 101 (or Physics 112), we were told that the average
human body
is equivalent to 100 watt light bulb as far as heat output.
Depending upon age, kids in a school would most likely be
considerably less.


You haven't seen my 11 year-old granddaughter - 250 Watt is more like
it.

Depending on activity level, you can _triple_ (or somewhat more) the
base number, which is in the 100-140 watt range.

A 250 watt kid is -not- all that extreme! grin

Also, I think that heat dissipation would be equivalent to body surfacce
area, which would make skinny kids radiate more (proportionally) than
chunky ones ...

grin

--
Best regards
Han
email address is invalid

In article ,
Han wrote:
(Robert Bonomi) wrote in
:

In article ,
Han wrote:
Mark & Juanita wrote in
:

From EDEE 101 (or Physics 112), we were told that the average
human body
is equivalent to 100 watt light bulb as far as heat output.
Depending upon age, kids in a school would most likely be
considerably less.


You haven't seen my 11 year-old granddaughter - 250 Watt is more like
it.

Depending on activity level, you can _triple_ (or somewhat more) the
base number, which is in the 100-140 watt range.

A 250 watt kid is -not- all that extreme! grin

Also, I think that heat dissipation would be equivalent to body surfacce
area, which would make skinny kids radiate more (proportionally) than
chunky ones ...

While you might think so, reality is somewhat counter-intuitive.
Total heat output is relatively -independant- of surface area. Less skin
just means more output per unit area.

Han wrote:

Mark & Juanita wrote in
:

From EDEE 101 (or Physics 112), we were told that the average human
body
is equivalent to 100 watt light bulb as far as heat output. Depending
upon age, kids in a school would most likely be considerably less.


You haven't seen my 11 year-old granddaughter - 250 Watt is more like it.


You know, I know exactly what you are saying -- our son has been like that
also.


--
If you're going to be dumb, you better be tough

On Sat, 01 Dec 2007 15:11:19 GMT, chuckb
wrote:

Kenneth wrote:

On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
wrote:


Now that has a few good answers. I would not have thought about the
freezing closed loops.


Howdy,

Any responsibly designed system protects against such
freezing...

All the best,


but on the other hand:

from your OP
"The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged."

any system that is operated outside it's design criteria risks failure!

good luck with yours!

chuck b:-)

Hi Chuck,

It would seem that I have not communicated clearly...

Indeed, the design folks tell me not to use any setback, but
they seem unable to tell me "why." Their lack of a
meaningful explanation was the cause of my original question
about the setback issue.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Nov 26, 11:48 pm, Kenneth
wrote:
Howdy,

This is way OT...(again), but:

We heat and cool our home geothermally (water to air
system.)

We would, of course, like to decrease our costs further if
we can, and so have explored the benefits of setting our
thermostat lower at those times when the house (or parts of
it) are not occupied.

The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged.

Of course, I have asked "why", but when I do, it seems that
smoke starts to come out of the phone. In essence, they say
that it is "best" but seem unable to say why.

Might any of you know what would be best in this regard ,
and particularly whether the issue of thermostat setback is
actually any different for geothermal systems?



The rate at which your house loses heat to the environment
depends in an almost linear fashion on the temperature difference
between your house and the outside environment.

So as your house cools, the rate at which it loses heat will
decrease. Keeping the house at the higher temperature means
it will constantly lose heat at that higher rate, and all of that heat
lost must be mad eup to maintain the temperature. If you let
it cool down and heat it back up the 'stored' heat that is lost
to the environment while cooling is exactly equal to the extra
heat needed to heat it back up. But the heat loss to the enviornment
is less the whol time during which the house is cooler than
normal.

Ergo, it ALWAY will use less heat to let it cool down and
heat it back up than to maintain it at the higher temperature.

What comes into play is the cost of pumping that heat into
your house at the higher rate for the short period of time
during which it heats back up. If that is down with auxillary
electric resistance heat that MAY cost more or use more
energy overall than just keeping it warm.

The presumption that you have an auxiliary heating system
may be part of the reason why you get advice to the
contrary. Another concern may be that cycling the
temperature may result in persistent cold spots or
condensation problems that could lead to overall
dissatisfaction with the system.

But mostly I doubt you have ever spoken on the
phone with anyone who actually studied heat
transfer phenomenon or even took a physics course
ever.

The other possibility suggested is that extracting heat
too fast from the groundwater could create a pool
of cooled water underground with a resultant lower
efficiency of heat extraction. That would depend
largely on the groundwater environment and how
extensive the heat exchange area is underground.

I doubt that a definitive general answer can be given
regarding that last concern. It would be highly dependent
on the specific situation.

--

FF

On Nov 27, 12:44 am, "Lew Hodgett" wrote:
"Kenneth" wrote:
We heat and cool our home geothermally (water to air
system.)

We would, of course, like to decrease our costs further if
we can, and so have explored the benefits of setting our
thermostat lower at those times when the house (or parts of
it) are not occupied.

The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged.

Of course, I have asked "why", but when I do, it seems that
smoke starts to come out of the phone. In essence, they say
that it is "best" but seem unable to say why.

Might any of you know what would be best in this regard ,
and particularly whether the issue of thermostat setback is
actually any different for geothermal systems?

In a nutshell, thermal inertia.

Once the system is balanced, it requires minimum energy to maintain
the balance.

Change the set point to a lower level, remain there for a while, then
return to the higher level requires a lot of thermal work.

Heat intensive industries such as steel, refineries, etc, run 24/7 for
just this reason.


No, the reason is that it costs them money to keep it warm and it also
costs them money to warm it up , but they can produce a product while
it is warm and not while it is warming up.

It is not how much they are spending on energy, it is their return on
that investment--less than zero (due to other operating costs)
while warming up, and greater than zero (hopefully) when at operating
temperature.

There are other considerations such as thermal stresses during warm-up
and cooling down.

--

FF

On Nov 27, 7:26 am, Robatoy wrote:

...

I was going to try to equate this with the reason why when you
increase the waterflow through your car's radiator by taking out the
thermostat, your engine will overheat. The water HAS to spend time in
the rad to be able to give up its heat. So the thermostat slows down
the waterflow. Conventional thinking would suggest that by increasing
the waterflow, it should cool better. (There are a few caveats in
there too, so everybody keep their shirts on.)

That is the first I ever heard of that.

The higher the flow rate the higher the Reynolds number and
therefor the higher the convective heat-transfer coefficient.
You may get less heat transferred per gram of water flowing
through the radiator, but not in inverse proportion to the
rate at which grams of water flow through. IOW you might
get only 75% of the heat loss per gram of water but will
have twice as many grams of water flowing through.

--

FF

Fred the Red Shirt wrote:
On Nov 27, 7:26 am, Robatoy wrote:
...

I was going to try to equate this with the reason why when you
increase the waterflow through your car's radiator by taking out the
thermostat, your engine will overheat. The water HAS to spend time in
the rad to be able to give up its heat. So the thermostat slows down
the waterflow. Conventional thinking would suggest that by increasing
the waterflow, it should cool better. (There are a few caveats in
there too, so everybody keep their shirts on.)

That is the first I ever heard of that.

The higher the flow rate the higher the Reynolds number and
therefor the higher the convective heat-transfer coefficient.
You may get less heat transferred per gram of water flowing
through the radiator, but not in inverse proportion to the
rate at which grams of water flow through. IOW you might
get only 75% of the heat loss per gram of water but will
have twice as many grams of water flowing through.

Yes, it's simply wrong in general. If one didn't get additional cooling
capacity when the thermostat opened as compared to when it is closed,
there would be insufficient cooling capacity to prevent overheating at
almost any operating condition.

Whatever "caveats" were suggested to counteract that would have to be
extreme, indeed...

--

On Dec 2, 6:18 pm, dpb wrote:
Fred the Red Shirt wrote:



On Nov 27, 7:26 am, Robatoy wrote:
...

I was going to try to equate this with the reason why when you
increase the waterflow through your car's radiator by taking out the
thermostat, your engine will overheat. The water HAS to spend time in
the rad to be able to give up its heat. So the thermostat slows down
the waterflow. Conventional thinking would suggest that by increasing
the waterflow, it should cool better. (There are a few caveats in
there too, so everybody keep their shirts on.)

That is the first I ever heard of that.

The higher the flow rate the higher the Reynolds number and
therefor the higher the convective heat-transfer coefficient.
You may get less heat transferred per gram of water flowing
through the radiator, but not in inverse proportion to the
rate at which grams of water flow through. IOW you might
get only 75% of the heat loss per gram of water but will
have twice as many grams of water flowing through.

Yes, it's simply wrong in general. If one didn't get additional cooling
capacity when the thermostat opened as compared to when it is closed,
there would be insufficient cooling capacity to prevent overheating at
almost any operating condition.

Whatever "caveats" were suggested to counteract that would have to be
extreme, indeed...

If he's talking bout a new engine them maybe removing the radiator
could confuse the computer and really screw things up--but since
normal operation is for the thermostat to open when the water gets
hot--how COULD it overheat by leaving ti open? Once it gets hot, it
would open anyways.

Sound's like an old wive's) mechanic's tale.

--

FF

On Dec 2, 7:56 pm, Fred the Red Shirt wrote:
On Dec 2, 6:18 pm, dpb wrote:



Fred the Red Shirt wrote:

...

Whatever "caveats" were suggested to counteract that would have to be
extreme, indeed...

If he's talking bout a new engine them maybe removing the radiator

Er, I meant removing the 'thermostat'.

There is little doubt that removing the radiator will cause the engine
to
overheat...

--

FF

On Sun, 2 Dec 2007 09:55:59 -0800 (PST), Fred the Red Shirt
wrote:

On Nov 26, 11:48 pm, Kenneth
wrote:
Howdy,

This is way OT...(again), but:

We heat and cool our home geothermally (water to air
system.)

We would, of course, like to decrease our costs further if
we can, and so have explored the benefits of setting our
thermostat lower at those times when the house (or parts of
it) are not occupied.

The folks who designed the heating system say that with
these systems, it is best to leave the set temp unchanged.

Of course, I have asked "why", but when I do, it seems that
smoke starts to come out of the phone. In essence, they say
that it is "best" but seem unable to say why.

Might any of you know what would be best in this regard ,
and particularly whether the issue of thermostat setback is
actually any different for geothermal systems?



The rate at which your house loses heat to the environment
depends in an almost linear fashion on the temperature difference
between your house and the outside environment.

So as your house cools, the rate at which it loses heat will
decrease. Keeping the house at the higher temperature means
it will constantly lose heat at that higher rate, and all of that heat
lost must be mad eup to maintain the temperature. If you let
it cool down and heat it back up the 'stored' heat that is lost
to the environment while cooling is exactly equal to the extra
heat needed to heat it back up. But the heat loss to the enviornment
is less the whol time during which the house is cooler than
normal.

Ergo, it ALWAY will use less heat to let it cool down and
heat it back up than to maintain it at the higher temperature.

What comes into play is the cost of pumping that heat into
your house at the higher rate for the short period of time
during which it heats back up. If that is down with auxillary
electric resistance heat that MAY cost more or use more
energy overall than just keeping it warm.

The presumption that you have an auxiliary heating system
may be part of the reason why you get advice to the
contrary. Another concern may be that cycling the
temperature may result in persistent cold spots or
condensation problems that could lead to overall
dissatisfaction with the system.

But mostly I doubt you have ever spoken on the
phone with anyone who actually studied heat
transfer phenomenon or even took a physics course
ever.

The other possibility suggested is that extracting heat
too fast from the groundwater could create a pool
of cooled water underground with a resultant lower
efficiency of heat extraction. That would depend
largely on the groundwater environment and how
extensive the heat exchange area is underground.

I doubt that a definitive general answer can be given
regarding that last concern. It would be highly dependent
on the specific situation.

Hello to all (again),

Well, I am the OP on this "Will I save if I use a thermostat
setback on my geothermal system" thread, and I believe that
I now have an answer:

Part of the hassle I faced in experimenting with this was
that for some reason, I kept thinking only of my house. We
have a number of electrical appliances there that are used
(essentially) randomly, and their use would certainly throw
off any comparisons that I could make over a relatively
short period of time.

I commented on that to my wife, and she said "So do the
experiment in the barn." (She did not actually say "So do
the experiment in the barn, you idiot", but that is what I
heard.)

Our office-barn is heated with exactly the same system as is
our house (water to air geo with no backup resistance heat)
and there is no variability of electrical consumption other
than the heating system for most of each day.

So, with that information, I did a very simple experiment. I
have run it only for six days but, as you will see, the
pattern seems quite clear:

I set the programmable thermostat to drop the "call heat"
temperature by 10 degrees F for 12 hours on alternating
nights.

Each morning, at the same time, I read the barn's electric
meter.

Finally, I got the degree days, and wind speed, from a
weather service site.

With that, I could calculate the ratio of KWH to Degree Day.
I have also included in the table below the reported max
wind speed for the day.


KWH/DD WS

Day 1: 1.2 (setback) 14

Day 2: 1.6 (no setback) 17

Day 3: 1.0 (setback) 8

Day 4: 1.3 (no setback) 0

Day 5: 1.0 (setback) 12

Day 6: 1.2 (no setback) 3


So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Kenneth wrote:
....

So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.

As at least one other poster noted, they're concerned w/ other factors
that aren't applicable in your case (primarily dominated by the use of
resistance electric heat in many/most systems)...

There are others including the potential freezeup, etc., that are
possible but imo they're mostly cya kinds of responses. Did you try the
Water Furnace people directly or contact the Okla State or some of the
other resources for other input?

--

On Sat, 08 Dec 2007 09:22:52 -0600, dpb
wrote:

Kenneth wrote:
...

So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.

As at least one other poster noted, they're concerned w/ other factors
that aren't applicable in your case (primarily dominated by the use of
resistance electric heat in many/most systems)...

There are others including the potential freezeup, etc., that are
possible but imo they're mostly cya kinds of responses. Did you try the
Water Furnace people directly or contact the Okla State or some of the
other resources for other input?

Howdy,

The CYA analysis makes sense to me, but as you probably
know, there is no real "freeze up" danger at all. These
systems simply turn themselves off is the incoming water is
too cold.

Also, as you may know "Water Furnace" is a brand name. Our
equipment is ClimateMaster.

I have communicated about all this at some length with the
ClimateMaster folks, with the geo folks from my electric
utility, and with the installer of the equipment. They all
have said "no setback" is best.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Kenneth wrote:
On Sat, 08 Dec 2007 09:22:52 -0600, dpb
wrote:

Kenneth wrote:
...

So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.
As at least one other poster noted, they're concerned w/ other factors
that aren't applicable in your case (primarily dominated by the use of
resistance electric heat in many/most systems)...

There are others including the potential freezeup, etc., that are
possible but imo they're mostly cya kinds of responses. Did you try the
Water Furnace people directly or contact the Okla State or some of the
other resources for other input?

Howdy,

The CYA analysis makes sense to me, but as you probably
know, there is no real "freeze up" danger at all. These
systems simply turn themselves off is the incoming water is
too cold.

The problem I've normally seen is on the once-through water exchange
systems (which is also what I think I recall being mentioned in one of
the earlier postings of a problem--whether it was yours or another I
don't recall) is the freezeup of the outlet when systems aren't running.
My opinion remains as I noted there is that if that's a problem for a
given system, it will be so whether there's a setback or not unless the
system is so undersized as to run continuously; hence my assessment of
that as a response as being in the "CYA" category.

Also, as you may know "Water Furnace" is a brand name. Our
equipment is ClimateMaster.

Yes, I had thought that was who you had said earlier...I don't know
ClimateMaster; had a Water Furnace system earlier and was pretty
impressed w/ their factory rep service/technical support.

I have communicated about all this at some length with the
ClimateMaster folks, with the geo folks from my electric
utility, and with the installer of the equipment. They all
have said "no setback" is best.

I think again all of those folks are addressing the general case still
rather than the specifics of a given installation and are still using
the answer that is easiest for them. It would be interesting if could
get to one of the actual research facilities that might address a
specific system rather than the general consumer response. If you were
still interested in pursuing it from that standpoint I'd again suggest
ORNL, TVA R&D (not power) or OSU might be more likely to answer a real
question.

--

On Sat, 08 Dec 2007 10:00:24 -0600, dpb
wrote:

Kenneth wrote:
On Sat, 08 Dec 2007 09:22:52 -0600, dpb
wrote:

Kenneth wrote:
...

So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.
As at least one other poster noted, they're concerned w/ other factors
that aren't applicable in your case (primarily dominated by the use of
resistance electric heat in many/most systems)...

There are others including the potential freezeup, etc., that are
possible but imo they're mostly cya kinds of responses. Did you try the
Water Furnace people directly or contact the Okla State or some of the
other resources for other input?

Howdy,

The CYA analysis makes sense to me, but as you probably
know, there is no real "freeze up" danger at all. These
systems simply turn themselves off is the incoming water is
too cold.

The problem I've normally seen is on the once-through water exchange
systems (which is also what I think I recall being mentioned in one of
the earlier postings of a problem--whether it was yours or another I
don't recall) is the freezeup of the outlet when systems aren't running.
My opinion remains as I noted there is that if that's a problem for a
given system, it will be so whether there's a setback or not unless the
system is so undersized as to run continuously; hence my assessment of
that as a response as being in the "CYA" category.

Also, as you may know "Water Furnace" is a brand name. Our
equipment is ClimateMaster.

Yes, I had thought that was who you had said earlier...I don't know
ClimateMaster; had a Water Furnace system earlier and was pretty
impressed w/ their factory rep service/technical support.

I have communicated about all this at some length with the
ClimateMaster folks, with the geo folks from my electric
utility, and with the installer of the equipment. They all
have said "no setback" is best.

I think again all of those folks are addressing the general case still
rather than the specifics of a given installation and are still using
the answer that is easiest for them. It would be interesting if could
get to one of the actual research facilities that might address a
specific system rather than the general consumer response. If you were
still interested in pursuing it from that standpoint I'd again suggest
ORNL, TVA R&D (not power) or OSU might be more likely to answer a real
question.

Hi again,

For me there are two (essentially unrelated) issues:

First, I am concerned with my system(s) and whatever savings
I might realize with the setbacks.

Second, I am a curious sort, and often enjoy understanding
this sort of thing.

Right now, my energies are focused on #1, and with my very
simple experiment, I do believe I have my answer.

#2 will have to wait a bit!

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Kenneth wrote:
....

First, I am concerned with my system(s) and whatever savings
I might realize with the setbacks.

Second, I am a curious sort, and often enjoy understanding
this sort of thing.

Right now, my energies are focused on #1, and with my very
simple experiment, I do believe I have my answer.

#2 will have to wait a bit!

The answer to the first is clear -- a lower setpoint is less total
integrated demand as compared to no setback so unless there are
mitigating factors such as the higher-rate aux heat (that you don't
have), then a setback will invariably be less input.

The other issues are also system-specific but the design issues have
been dealt with by the various research groups. I never had a
convenient water source so didn't pursue the logistics of them that much.

--

Kenneth wrote:


Hello to all (again),

Well, I am the OP on this "Will I save if I use a thermostat
setback on my geothermal system" thread, and I believe that
I now have an answer:

Part of the hassle I faced in experimenting with this was
that for some reason, I kept thinking only of my house. We
have a number of electrical appliances there that are used
(essentially) randomly, and their use would certainly throw
off any comparisons that I could make over a relatively
short period of time.

I commented on that to my wife, and she said "So do the
experiment in the barn." (She did not actually say "So do
the experiment in the barn, you idiot", but that is what I
heard.)

Our office-barn is heated with exactly the same system as is
our house (water to air geo with no backup resistance heat)
and there is no variability of electrical consumption other
than the heating system for most of each day.

So, with that information, I did a very simple experiment. I
have run it only for six days but, as you will see, the
pattern seems quite clear:

I set the programmable thermostat to drop the "call heat"
temperature by 10 degrees F for 12 hours on alternating
nights.

Each morning, at the same time, I read the barn's electric
meter.

Finally, I got the degree days, and wind speed, from a
weather service site.

With that, I could calculate the ratio of KWH to Degree Day.
I have also included in the table below the reported max
wind speed for the day.


KWH/DD WS

Day 1: 1.2 (setback) 14

Day 2: 1.6 (no setback) 17

Day 3: 1.0 (setback) 8

Day 4: 1.3 (no setback) 0

Day 5: 1.0 (setback) 12

Day 6: 1.2 (no setback) 3


So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.

All the best,

What was the recovery time after the setback days?

Kenneth wrote:

Hello to all (again),

Well, I am the OP on this "Will I save if I use a thermostat
setback on my geothermal system" thread, and I believe that
I now have an answer:

Part of the hassle I faced in experimenting with this was
that for some reason, I kept thinking only of my house. We
have a number of electrical appliances there that are used
(essentially) randomly, and their use would certainly throw
off any comparisons that I could make over a relatively
short period of time.

I commented on that to my wife, and she said "So do the
experiment in the barn." (She did not actually say "So do
the experiment in the barn, you idiot", but that is what I
heard.)

Our office-barn is heated with exactly the same system as is
our house (water to air geo with no backup resistance heat)
and there is no variability of electrical consumption other
than the heating system for most of each day.

So, with that information, I did a very simple experiment. I
have run it only for six days but, as you will see, the
pattern seems quite clear:

I set the programmable thermostat to drop the "call heat"
temperature by 10 degrees F for 12 hours on alternating
nights.

Each morning, at the same time, I read the barn's electric
meter.

Finally, I got the degree days, and wind speed, from a
weather service site.

With that, I could calculate the ratio of KWH to Degree Day.
I have also included in the table below the reported max
wind speed for the day.


KWH/DD WS

Day 1: 1.2 (setback) 14

Day 2: 1.6 (no setback) 17

Day 3: 1.0 (setback) 8

Day 4: 1.3 (no setback) 0

Day 5: 1.0 (setback) 12

Day 6: 1.2 (no setback) 3


So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.

All the best,

I'm wondering if your savings aren't as great as you think. The reason
is that on a setback day, you have zero electrical usage as the house
coasts down to the setback temp. The next day's usage gets nailed with
the recovery time usage. Perhaps week long vs day long alternating
periods might mitigate some of this effect?

On Dec 8, 6:57 pm, Doug Winterburn wrote:
Kenneth wrote:

Hello to all (again),

Well, I am the OP on this "Will I save if I use a thermostat
setback on my geothermal system" thread, and I believe that
I now have an answer:

Part of the hassle I faced in experimenting with this was
that for some reason, I kept thinking only of my house. We
have a number of electrical appliances there that are used
(essentially) randomly, and their use would certainly throw
off any comparisons that I could make over a relatively
short period of time.

I commented on that to my wife, and she said "So do the
experiment in the barn." (She did not actually say "So do
the experiment in the barn, you idiot", but that is what I
heard.)

Our office-barn is heated with exactly the same system as is
our house (water to air geo with no backup resistance heat)
and there is no variability of electrical consumption other
than the heating system for most of each day.

So, with that information, I did a very simple experiment. I
have run it only for six days but, as you will see, the
pattern seems quite clear:

I set the programmable thermostat to drop the "call heat"
temperature by 10 degrees F for 12 hours on alternating
nights.

Each morning, at the same time, I read the barn's electric
meter.

Finally, I got the degree days, and wind speed, from a
weather service site.

With that, I could calculate the ratio of KWH to Degree Day.
I have also included in the table below the reported max
wind speed for the day.

KWH/DD WS

Day 1: 1.2 (setback) 14

Day 2: 1.6 (no setback) 17

Day 3: 1.0 (setback) 8

Day 4: 1.3 (no setback) 0

Day 5: 1.0 (setback) 12

Day 6: 1.2 (no setback) 3

So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.

All the best,

I'm wondering if your savings aren't as great as you think. The reason
is that on a setback day, you have zero electrical usage as the house
coasts down to the setback temp. The next day's usage gets nailed with
the recovery time usage. Perhaps week long vs day long alternating
periods might mitigate some of this effect?

So long as he reads the meter after his house i swarmed up,
it doesn't matter. But it should be well after it has warmed up
as lingering cold spots away from the thermostat will have the
effect you suggest. It would be better to read the meter at the
same time every night, right before the setback.


--

FF