I live in Southern Maryland. This year we had a heat pump installed
with propane backup heat. Early on we were using a lot of propane
because I was turning the heat down to 55 at night. I have rectified
this by setting the heat to 68 when we are home and 66 when we are away
or asleep. Is 2 degrees the most I should fluctuate it on a daily
basis?

Secondly and this is my main question... I have heard that heat pumps
are no longer efficient at 30 degrees. So when I see a stretch of a few
days that are going to be cold, below 30 degrees, should I just turn on
emergency heat? Thus turning off the heat pump for these cold days when
it would be inefficient? Currently it tries until it can't keep up. I
am thinking this time when it trying it is just burning my electricity
and cash. Would this be the most efficient way to heat?

I wouldn't fluctuate it at all without a special programmed themostat
designed to prevent backup heat going on when exiting setback cycle.

You ask an interesting question about heatpumps. I would presume that the
controls for the heatpumps are designed to be smart enuf that you don't have
to worry about bypassing the heatpump. The bypass is for if the heatpump is
broken.


"Home owner" wrote in message
oups.com...
I live in Southern Maryland. This year we had a heat pump installed
with propane backup heat. Early on we were using a lot of propane
because I was turning the heat down to 55 at night. I have rectified
this by setting the heat to 68 when we are home and 66 when we are away
or asleep. Is 2 degrees the most I should fluctuate it on a daily
basis?

Secondly and this is my main question... I have heard that heat pumps
are no longer efficient at 30 degrees. So when I see a stretch of a few
days that are going to be cold, below 30 degrees, should I just turn on
emergency heat? Thus turning off the heat pump for these cold days when
it would be inefficient? Currently it tries until it can't keep up. I
am thinking this time when it trying it is just burning my electricity
and cash. Would this be the most efficient way to heat?

My thermostat is very fancy with all the whistles and bells. Not sure
if it tries not to use auxiliary heat or not but it does figure out
when to come on to have the house to the desired temp at a given time.

The thermostat also has options for exterior thermometer to help it
decide when to skip straight to aux heat. We do not have the exterior
thermometer. If I had any idea what to install and how to install it I
would. The heat pump itself may have equipment and the programming to
realize the cold temperature and skip straight to aux heat but I have
not read this anywhere.

According to Art :
I wouldn't fluctuate it at all without a special programmed themostat
designed to prevent backup heat going on when exiting setback cycle.

You ask an interesting question about heatpumps. I would presume that the
controls for the heatpumps are designed to be smart enuf that you don't have
to worry about bypassing the heatpump. The bypass is for if the heatpump is
broken.

Right. A heat pump control system is designed to switch over to backup heat
when it makes economic sense to do so [+].

It's a balance between HP/outside temperature efficiency and
cost per BTUs in the backup system.

If it was installed/adjusted correctly and is operating properly,
don't second guess the control system, it'll do a much more effective
job at minimizing cost than you can erratically flipping a switch.
Even if the propane cost has shifted around a bit.

In other words, leave it in auto, unless the control system (or HP)
is outright failing and can't keep your house warm.

[+] The other time a HP switches to backup heat is if the inside
temperature is "too far" away from the thermostat set-point. The
threshold for "too far" is usually something on the order of 3-5
degrees. The control circuitry figures that the HP is unable to keep
up if the temperature difference is too high, and switches on emergency
heat to catch up. This makes particular sense when you realize that
a HP can't produce as many BTUs per hour as a straight gas furnace.

So, if you open all the doors and windows during a blizzard, the control
system automatically notices the gross temperature difference, and switches
on backup to try and get the temperature back in the comfort range as soon
as possible.

The difficulty arises with setback thermostats. They cause large abrupt
changes in the T-stat setting. "Oops, we can't keep up, switch on the backup!".
You need to use special programmable thermostats that either bring up the temperature
slowly (within the HP's ability to keep up - some of these T-stats have programmable
ramp-up rates I think), or inhibit backup heat during a catchup interval.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

"Home owner" wrote in message
oups.com...
I live in Southern Maryland. This year we had a heat pump installed
with propane backup heat. Early on we were using a lot of propane
because I was turning the heat down to 55 at night. I have rectified
this by setting the heat to 68 when we are home and 66 when we are away
or asleep. Is 2 degrees the most I should fluctuate it on a daily
basis?

Secondly and this is my main question... I have heard that heat pumps
are no longer efficient at 30 degrees. So when I see a stretch of a few
days that are going to be cold, below 30 degrees, should I just turn on
emergency heat? Thus turning off the heat pump for these cold days when
it would be inefficient? Currently it tries until it can't keep up. I
am thinking this time when it trying it is just burning my electricity
and cash. Would this be the most efficient way to heat?

If it hasn't been done already, you should have had an outdoor thermostat
installed that automatically switches over to propane when it gets down to a
certain temperatrure. SMECO recommends 35 degrees but I have seen it set as
low as 28 and as high as 42. Depends on your comfort. Who installed your
system? T.N. Bowes? Or did one of the propane companies install it?

I have a mnaual switch for the aux heat (on my heat pump) and I only turn it
on when the temps get down in the low 20s. I have no backup other than the
"heat strips" (aux heat) and my heats fine. My electric bill still does not
match what I was spending on oil.

I'm moving if SMECO raises the damn rates again......

Interesting argument- that you used a lot of propane because of
night-time setback. If one follows from the other, something in between
is totally hosed, and is the cause. Or something totally separate is
screwed up. Like- leak, erroneous meter reading, whatever.

J

you defenitly want to switch to backup when the heat pump has to use
defrost cycles to melt ice off of the outdoor coils... generally
around 32.

I switch over at 40 bacause I factor in the wear and tear on the poor
compressor running its guts out ...

Mark

Potter put my system in. I would be interested in an outdoor
thermostat... should I contact Potter?

Also are you saying that because I set my thermostat low at night and
aux heat is coming on to bring it up to temp in the morning there is a
problem with my system? This is only a problem I had when I was setting
the heat way back at night. If this is a tell tail to a real problem I
want to get it fixed now!

Thanks for the replies!

Potter put my system in. I would be interested in an outdoor
thermostat... should I contact Potter?

Also are you saying that because I set my thermostat low at night and
aux heat is coming on to bring it up to temp in the morning there is a
problem with my system? This is only a problem I had when I was setting
the heat way back at night. If this is a tell tail to a real problem I
want to get it fixed now!

Thanks for the replies!

wrote:
Interesting argument- that you used a lot of propane because of
night-time setback. If one follows from the other, something in
between is totally hosed, and is the cause. Or something totally
separate is screwed up. Like- leak, erroneous meter reading, whatever.

J

Night setback tends to kick in the backup for two reasons. First
consider when the set back is likely to be canceled. Usually in the morning
at the coldest part of the day. Far more likely to kick in if for no other
reason that it is not too cold outside. I don't know about their control
systems, but I would not be surprised if they detected the difference
between the set temp and the current temp and would decide that it was going
to need to kick in the backup source to help bring up the temperature in a
reasonable amount of time.

--
Joseph Meehan

Dia duit

My heat pump run at 17 degs, and then the Natural gas furnace takes over, I
do get a reduced electric rate in the winter because of the heat pump, so I
let it run till it can't keep up. The installer should of set the outside
unit to run down below 30 degs, or to where its not keep you comfortable.

Tom
\

"Home owner" wrote in message
oups.com...
I live in Southern Maryland. This year we had a heat pump installed
with propane backup heat. Early on we were using a lot of propane
because I was turning the heat down to 55 at night. I have rectified
this by setting the heat to 68 when we are home and 66 when we are away
or asleep. Is 2 degrees the most I should fluctuate it on a daily
basis?

Secondly and this is my main question... I have heard that heat pumps
are no longer efficient at 30 degrees. So when I see a stretch of a few
days that are going to be cold, below 30 degrees, should I just turn on
emergency heat? Thus turning off the heat pump for these cold days when
it would be inefficient? Currently it tries until it can't keep up. I
am thinking this time when it trying it is just burning my electricity
and cash. Would this be the most efficient way to heat?

In 1978 my new home included a GE (now Trane) high (for those days)
efficiency heat pump. The home was located 8 miles west of Atlantic
City. NJ had a moratorium on new connections for gas as was in short
supply.

At the time I was taking a job as a generation performance engineer for
the local electric utility. I confirmed (I'm a mechanical engineer
(PE)) the capacity rating of the heat pump vs the heating load
calculation. I also had the company's heat pump engineer check it
also. The heat pump could carry the house down to 15 degrees without
backup heat.

18 years later we moved and sold the house. The original heat pump was
still running well. Total repairs during that 18 year period was
NOTHING.

I suggest that you just confirm what the manufacturer suggests is the
appropriate balance point setting and leave the controls to do their
job.

Low outside temperatures do reduce the COP (coeefficient of
performance) and do reduce the temperature of the air handler output.
Those two items may cause some people to want to use backup heat, but
why try and second guess the manufacturer?



twfsa wrote:
My heat pump run at 17 degs, and then the Natural gas furnace takes over, I
do get a reduced electric rate in the winter because of the heat pump, so I
let it run till it can't keep up. The installer should of set the outside
unit to run down below 30 degs, or to where its not keep you comfortable.

Tom
\

"Home owner" wrote in message
oups.com...
I live in Southern Maryland. This year we had a heat pump installed
with propane backup heat. Early on we were using a lot of propane
because I was turning the heat down to 55 at night. I have rectified
this by setting the heat to 68 when we are home and 66 when we are away
or asleep. Is 2 degrees the most I should fluctuate it on a daily
basis?

Secondly and this is my main question... I have heard that heat pumps
are no longer efficient at 30 degrees. So when I see a stretch of a few
days that are going to be cold, below 30 degrees, should I just turn on
emergency heat? Thus turning off the heat pump for these cold days when
it would be inefficient? Currently it tries until it can't keep up. I
am thinking this time when it trying it is just burning my electricity
and cash. Would this be the most efficient way to heat?

The system is York. Our propane supplier is Southern Maryland Gas. The
only one that does not have a minimum purchase. And you are correct we
do live in Waldorf. I will check about a fossil fuel kit.

Thanks!

"Home owner" wrote in message
ups.com...
The system is York. Our propane supplier is Southern Maryland Gas. The
only one that does not have a minimum purchase. And you are correct we
do live in Waldorf. I will check about a fossil fuel kit.

Thanks!

YORK??!!! YUK!!!

;-]


It doesn't have to be a fossil fuel kit, though it works the same way. The
way I equate it:

Outdoor thermostat and a bonnet switch: $125 in parts.
Fossil fuel kit: $300-$400 to do the same thing.

YMMV.......

On 14 Feb 2006 07:41:48 -0800, Home owner wrote:

I live in Southern Maryland. This year we had a heat pump installed
with propane backup heat. Early on we were using a lot of propane
because I was turning the heat down to 55 at night. I have rectified
this by setting the heat to 68 when we are home and 66 when we are away
or asleep. Is 2 degrees the most I should fluctuate it on a daily
basis?

Have same setup here - NW GA. My heat pump has a thermostat in it's cabinet
that turns the propane furnace on at whatever temperature it is set to. Mine
is located underneath the service panel on the heat pump in a box about 8
inches square, there is a temperature probe exiting the box. Inside the box
is a knob which has temperatures marked around it - you just turn the knob to
the temperature you want the heat pump turned off. Pretty simple to change
and not too hard to find - at least on my unit. BTW, make sure the bulb on
the probe isn't mounted so that the sun shines on it for proper operation.

My system also has a plenum sensor that detects when the heat pump goes into
defrost and turns on the aux heat during defrost to prevent cold air coming
from the returns. I don't know that this ever occurs with my outdoor
thermostat setting of 35F, never noticed if it has.

Concerning the temperature setback on your thermostat. If you have an
electronic thermostat, some (may be many) have a setting which will gradually
raise the temperature from the lower setting to the higher setting gradually
to prevent the auxillary heat coming on when the temperature outside does not
warrant it. Some use a set amount of time per degree(s) others learn how long
it takes to reach the desired temp and base calculations on that - I have no
experience with the latter, only read about them. IIRC, mine had a switch to
set before mounting the thermostat to do this. Your manual will tell you if
the thermostat has this feature and what, if anything, needs to be done to
activate the feature.

You should note that if you MANUALLY raise the temperature more than a few
(dunno what it is offhand, but 5 comes to mind) degrees, the auxillary heat
will come on regardless of the outdoor temperature. Since the change was done
manually, the thermostat will not use the gradual method that is used for
setback.

Secondly and this is my main question... I have heard that heat pumps
are no longer efficient at 30 degrees. So when I see a stretch of a few
days that are going to be cold, below 30 degrees, should I just turn on
emergency heat? Thus turning off the heat pump for these cold days when
it would be inefficient? Currently it tries until it can't keep up. I
am thinking this time when it trying it is just burning my electricity
and cash. Would this be the most efficient way to heat?

You should not need to manually change the thermostat setting to aux heat
unless your heat pump isn't working or you want to use a portable generator
to operate the furnace - most won't run a heat pump but will run a furnace
since it is mostly just operating a fan. NOTE: Quite a few long-running and
nasty threads have appeared in this group concerning the use of portable
generators when the power is out and I won't go into any of that except to
say that you should VERY THOROUGHLY RESEARCH THE ISSUE and FOLLOW APPROPRIATE
SAFETY PRECAUTIONS AND PROCEDURES - nuff said and I won't respond to any
comments regarding this issue.

As mentioned above, the outdoor thermostat should take care of those times
that the temperature is low. The first thing I would do is check to see if
there was some method of turning off the heat pump below a certain outdoor
temperature installed in the system, if not, get one installed. If something
is installed, it sounds like the cutoff temperature is set too low and needs
to be adjusted up to whatever point you're comfortable with.

IIRC, I have read that there are some indoor thermostats that have a probe
that runs outdoors which is used instead of the thermostat in the heat pump
enclosure that I am familiar with. If you have one of these thermostats, you
need to make sure that the probe is properly installed. This may be an
optional item and the outdoor thermostat I'm familiar with may work fine with
these thermostats also.

HTH.

Later, Mike
(substitute strickland in the obvious location to reply directly)
-----------------------------------


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Joseph Meehan wrote:
snip
Night setback tends to kick in the backup for two reasons. First
consider when the set back is likely to be canceled. Usually in the morning
at the coldest part of the day. Far more likely to kick in if for no other
reason that it is not too cold outside. I don't know about their control
systems, but I would not be surprised if they detected the difference
between the set temp and the current temp and would decide that it was going
to need to kick in the backup source to help bring up the temperature in a
reasonable amount of time.


Especially if the OP was setting back the thermostat ~13 degrees at
night as could be inferred from his post. No way a heat pump is going
to recover from that on a cold night without some help.

I almost feel like I am using too little gas with my heat pump. I live
in NC and have used a whopping 6 cf this year, since the gas backup on
the downstairs heat pump is the only gas appliance. With the base
charges it works out to about $11/cf Don't know why they only
installed gas on first floor and no gas water heater or stove when they
built the place, although I guess it was the cheapest way for the
builder to be able to claim "gas heat".

On 15 Feb 2006 09:23:36 -0800, Brian Attwood wrote:

I almost feel like I am using too little gas with my heat pump. I live
in NC and have used a whopping 6 cf this year, since the gas backup on
the downstairs heat pump is the only gas appliance. With the base
charges it works out to about $11/cf Don't know why they only
installed gas on first floor and no gas water heater or stove when they
built the place, although I guess it was the cheapest way for the
builder to be able to claim "gas heat".

I have similar situation - the furnace is the only gas (propane) appliance. I
did that because I wanted a gas furnace, but the local EMC gave me a $1000
rebate, a free underground drop of 700 ft w/transformer by house, and a free
50 gal Marathon water heater (lists as $693.50 at Granger) for going total
electric (dual fuel counts as total electric for their purposes). Maybe the
builder got a similar package. Since the only gas appliance I really wanted
was the furnace, I got my cake and ate it too :-)

Later, Mike
(substitute strickland in the obvious location to reply directly)
-----------------------------------


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