Sure it does, The cool room still has heat in it. When the refrigerant
goes through those coils the heat in the room heats up the refrigerant and
makes it boil into a vapor.. Then the vapor is compressed and that makes it
hotter. It then goes outside and the hot vapor is cooled off by the outside
air and it goes to a liquid. It is just a mater of what is actually hot and
what is cool, or less hot.
well yes, once you cross that "balance point" where the heat available can no longer match the heat needed, then the house will get colder.
And consider that when the outside temp falls such that the outdoor evap starts to ice up, the heat exchange efficiency gets even worse, so yes there is a sort of sudden decrease in performance when the outdoor coil starts to ice up.
Looking at performance curves is not the same is living with one.
I'm wondering if this could be defrost cycle. The 3 minute thing sounds
like it might be. On my HP/propane furnace, it will sometime, but not
always do that, and then switch back to straight HP. Actually, the unit
is running in AC mode using the aux heat (propane in my case) to
evaporate any ice on the outside unit. I think the unit guesses, based
one outside temp and maybe other factors, how often to de-ice. Much
depends on the outside humidity, too. In my case, it seems to do it way
too much, but the alternative, ice build up, wouldn't be good. So I
figure they error on the side of safety.
On Saturday, November 9, 2013 7:54:59 AM UTC-5, Art Todesco wrote:
Two things. It's my understanding that heat pumps just
reverse the compressor flow to heat the outside coil for
defrosting. Do they turn on aux heat at the inside
unit while doing that? I never really thought about it
but I guess it might be needed. Otherwise you'd get cold
air blowing into the house. So the short 3 min aux heat
cycle sounds like it could be that.
But even if that is the case and it was set wrong, it
seems kind of strange to have the defrost cycle even
able to be set at 47F and above, no? You would think that
the setting range would be a lot lower to avoid problems
On my HP/propane furnace, it will sometime, but not
IT really depends on your thermostat. We had a new heatpump with
electric backup heat installed in a rental property a couple of years
ago. A new programmable thermostat was included. We discovered that the
backup heat would come on if the thermostat discovered the room
temperature was more than 2 degrees lower than the set point of the
We had the same type programmable thermostat installed in our current
mfg. home with heat pump. Same thing with the thermostat. More than one
degree difference and the backup heat comes on.
The reason is efficiency. The least cost heating is to maintain the same
temperature night and day. The heat pump will do this best when the set
temperature and the room temperature remain the same.
Set your thermostat to the temperature you want, for every day of the
week, both night and day. A one degree lower night temp will keep the
backup off, but will run the heatpump steady until the house temp comes
up to the daytime temp.
The heating company will not tell you this up front.
On Saturday, November 9, 2013 10:53:16 AM UTC-5, Paul Drahn wrote:
Only if aux heat, eg electric has to kick in to get the temp
back up. Otherwise, with say a nat gas or oil furnace, cost is lower
if you set it back at night. If you can't set it back, then
you're going to be needing to supply more heat to the house
to keep it maintained constantly. That's a negative.
The heat pump will do this best when the set
That's not all that unusual. A new thermostat is in order.
That's ridiculous. The thermostat wouldn't last the week.
Not believing it. Heat pumps can take a long time to recover in
really cold weather but in somewhat warmer weather there is no reason
to waste the energy. I prefer it colder at night that during the day.
Any system that didn't allow me the flexibility would soon be gone.
So what? That's true of any system. That's how thermostats work.
I think you should have him come back out and reset it so the aux indicator
light comes on. Should be no big deal and since it is a new system they
should have no problem doing that for you. Even if you could figure out how
to do that change yourself, I think that you would be better off having the
installation company tech do it. That way, they won't be able to say that
you messed something up by working on it yourself (even if you didn't).
Also, there is an alt.hvac Usenet newsgroup in case you want to try your
post there. It used to be an awful group full of nasty morons, but lately it
seems more sane and sometimes helpful.
Let us know what you end up doing and what the outcome is on this.
I'd want to know but that's your decision.
Smart thermostats can control the aux heat usage. Mine is set up to
run without aux for two hours before turning it on[*]. It would be
better to know the outside temperature but I don't have that option.
[*]it might be set up to disable aux heat completely now - can't
remember how I left it
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