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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