On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
wrote:


What was the recovery time after the setback days?

Hi Doug,

I don't know with certainty, but I do know it to be less
than an hour.

All the best,
--
Kenneth

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In article ,
Kenneth wrote:

On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
wrote:


What was the recovery time after the setback days?

Hi Doug,

I don't know with certainty, but I do know it to be less
than an hour.

All the best,

Please be careful on high wind load, very cold days - I would suggest
that if you know that the next day is going to be that way you not do
the setback.

I have had Geothermal for more than 20 years, in the early winter and in
the spring, set back saves a lot of money, but from about the middle of
December to the End of February here in Michigan, we do not do a
setback, since the secondary electric elements cost way more than the
savings.

I am looking at adding solar thermal heating the south wall of the house
next summer to further reduce the winter heating bill. I have 60 feet of
southern facing wall that is in direct sunlight almost all of the day.
That should give me a good thermal boost on even partly cloudy days.

Doug

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?

That's an effect if compares only one to the other. The point is,
however, that the time integral demand over the days w/ setback is lower
than without. Over a period of time when the average daily temp and
wind differences average out, the net will still be less with less
demand as a simple heat balance will show.

The better overall test would indeed, be to run for a longer period of
time at each operating mode and then compensate for the correlating
variables. Of course, the ideal test would be to hold the environment
fixed...

--

Doug Houseman wrote:
In article ,
Kenneth wrote:

On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
wrote:

What was the recovery time after the setback days?
Hi Doug,

I don't know with certainty, but I do know it to be less
than an hour.

All the best,

Please be careful on high wind load, very cold days - I would suggest
that if you know that the next day is going to be that way you not do
the setback.

I have had Geothermal for more than 20 years, in the early winter and in
the spring, set back saves a lot of money, but from about the middle of
December to the End of February here in Michigan, we do not do a
setback, since the secondary electric elements cost way more than the
savings.
....

OP has stated a zillion times already he has no aux heating and the unit
is sized to handle it w/o. So the aux heat is not an issue for him...

--

On Sat, 08 Dec 2007 16:35:50 -0500, Doug Houseman
wrote:

In article ,
Kenneth wrote:

On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
wrote:


What was the recovery time after the setback days?

Hi Doug,

I don't know with certainty, but I do know it to be less
than an hour.

All the best,

Please be careful on high wind load, very cold days - I would suggest
that if you know that the next day is going to be that way you not do
the setback.

I have had Geothermal for more than 20 years, in the early winter and in
the spring, set back saves a lot of money, but from about the middle of
December to the End of February here in Michigan, we do not do a
setback, since the secondary electric elements cost way more than the
savings.

I am looking at adding solar thermal heating the south wall of the house
next summer to further reduce the winter heating bill. I have 60 feet of
southern facing wall that is in direct sunlight almost all of the day.
That should give me a good thermal boost on even partly cloudy days.

Doug

Hi Doug,

Your offer good thoughts for the general geo situation, but
we do not have resistance auxiliary heat in either of our
two buildings. Our systems were designed for 20 year cold
days.

All the best,
--
Kenneth

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

On Sat, 08 Dec 2007 15:59:46 -0600, dpb
wrote:

OP has stated a zillion times already he has no aux heating and the unit
is sized to handle it w/o. So the aux heat is not an issue for him...

Now a zillion and one...BG

All the best,
--
Kenneth

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

On Sat, 08 Dec 2007 15:37:58 -0600, dpb
wrote:

Of course, the ideal test would be to hold the environment
fixed...

Here in New Hampshire, we often try...

All the best,
--
Kenneth

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