Shouldn't Heat Pump run 100% on Coldest Days?

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Old 12-15-19, 08:22 AM
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Question Shouldn't Heat Pump run 100% on Coldest Days?

We just got a brand new Airease single stage heat pump installed with electric heat strips for aux/backup. The thermostat we had installed was a Sensi Touch Smart Thermostat. I have my heat pump's cycle rate setting turned to "slow" for efficiency's sake, which allows for a decent swing in temp (sometimes it dips to 4ish degrees below our set temp.)

I'm in Ohio so it can get plenty cold in the winter with high temps never getting above the freezing point. A few days ago on Dec 11th was one of those days. I EXPECTED the heat pump to run 100% of the time (aside from when it's defrosting the outside unit anyway.) My understanding of how these units would work is that the heat pump itself can keep up with your room temp heating needs until externals temps reach around the freezing point, at which point the heat pump starts to lose efficiency and the BTUs it's pumping into the house aren't enough to keep us at our set thermostat temp (69F.) So that's what the aux heat source is for then... kicking on in tandem with the heat pump running when it notices the heat pump itself is having trouble reaching the set temp. In my own head, it stood to reason that in the conditions like those on Dec 11th the heat pump would run 100% of the time and the AUX heat would be turning on and off as needed to keep us within our desired range.

The Sensi app has a "usage" section that shows me how long each stage ran. For Dec 11th it's showing the "Heating" ran for 15h 42m, the "Aux Heating" ran for 2h 55m, and the "Fan Only" for 15m. What do I find odd about this? There's another 5 hours in the day where apparently nothing was running. What's my concern?

My concern is that what's happening is the aux heat turns on and gets me to my set room temp on the thermostat, at which point BOTH heat sources turn off, even the heat pump. Then the temp swings back down by a few degrees, the heat pump turns on, it has trouble keeping up, the aux heat turns on, it gets to our set temp, everything turns off, and the cycle continues. If that is what's happening, this seems like a VERY inefficient way to run, both because it's causing the heat pump to cycle (and it takes a few minutes to get back to peak efficiency) and because ultimately it's causing the aux heat to turn on more than is needed because the heat pump isn't constantly pumping heat into the house.

I'm new to this sort of system and my own understanding above is a combination of light research and what I thought was common sense, so I don't know if I'm missing something here. Is anyone out there knowledgeable about such things and can chime in to give some insight and either allay or confirm my fears? Thanks!
 
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Old 12-15-19, 08:29 AM
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I should mention I have "Boost" mode turned off, which for Sensi is the setting that allows aux heat to kick on when you adjust the temp by 3 degrees so it reach that point faster. In other words: I don't care how LONG it takes my system to reach a desired temp so much as I care about efficiency. I only want aux heat coming on when the heat pump literally can't keep up.
 
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Old 12-15-19, 08:58 AM
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Originally Posted by nightcabbage
So that's what the aux heat source is for then... kicking on in tandem with the heat pump running when it notices the heat pump itself is having trouble reaching the set temp.
1) Eh, not necessarily.
While it depends on single stage/2 stage and low-high efficiency, I don't think it's as much about recovery as about cost efficiency.

Starting with physics, at some outside temperature , a compressor that relies on moving exterior heat will use more electricity MOVING heat to where you need it, than a electric heater MAKING heat where you need it. Yes, your compressor COULD do it,
edit - per spec sheet, your compressor IS high efficiency, so it CAN work down to 17 degrees, but has to work harder
But, if you have electric heat, why beat up the compressor? Let the resistance heat do the job it was engineered to do, and let the heat-pump do the job it was engineered to do, at the point where it is most efficient.

Moving to engineering, one logical way to increase efficiency would be to use a "mixed mode" heat. Say you want 72 degree temperature when it's 32 degrees outside. By running the heat pump in "highest efficiency" range you could cheaply raise the air temperature part-way (say 20 degrees) which gets you to 52 degrees at high-efficiency and low cost; then use the electric heat portion for the remaining 20 degrees to achieve the desired 72 degrees.
This sort of "mixed mode" would be more efficient than either compressor or resistance components running by themselves.

2) Sounds like the thermostat is programmed
A) Comfort
B) Efficienty

and you want
A) Efficiency
B) Comfort

You might try adjusting the fan to better distribute the heat through all the air in the house. I found that circulating air helped smooth out heat/cool cycles. So I either A) leave the heating system fan on circulate OR B) add a simple box fax to circulate air around the first floor. (my 1st floor layout allows a circular air path.) Smoothing out temperature gradients (e.g. stopping warm air from going directly up to the ceiling and then up staircase, leaving feet and calves in a pool of cold air increased comfort.
 

Last edited by Hal_S; 12-15-19 at 09:53 AM.
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Old 12-15-19, 10:13 AM
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This sort of "mixed mode" would be more efficient than either compressor or resistance components running by themselves.
Well, I guess that's what I was referring to when I stated the aux heat source kicks on in tandem with the heat pump when it needs to. I'm assuming that's how it works, as I wasn't under the impression the heat pump turns off when aux turns on. Perhaps there's some differences in what you're suggesting though, which is that rather than the heat pump running 100% of the time and the aux heat strips kicking on and off, both sources may actually kick on and off together... and that would somehow be MORE efficient than the former? Is that effectively what you're saying? Because that would essentially explain what I seem to be seeing - though it still seems counter intuitive given the loss of heat pump efficiency with each cycle and there are times when it wouldn't be running and producing heat at all.

As far as the thermostat programming... there's very little I can do to affect the efficiency other than adjust the cycle rate down, which I have all the way to it's lowest setting. We have a fairly open floor plan with low ceilings and our new blower fan is really pumping out the air, so I'm not super worried about the air circulation.
 
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Old 12-15-19, 03:27 PM
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Originally Posted by nightcabbage
both sources may actually kick on and off together... and that would somehow be MORE efficient than the former? Is that effectively what you're saying?
Yes.
Ideal gas law is (Pressure X Volume = Temperature)

A heat pump uses compression to make outdoor air warm, then uses that to warm the house. The lower the outside temperature, the more you have to compress the outside air to get warm air.

In contrast, electric heat directly adds heat to inside air- Watts = Volts x Amps

At some point, using electricity to directly generate HEAT becomes more efficient that using electricity to COMPRESS the air to indirectly generate HEAT.
 
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Old 12-18-19, 06:27 PM
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If the temp gets to that point, then I'd assume the most efficient solution would be to stop the heat pump completely and rely totally on the heat strips. But I'm assuming that point is pretty darned cold (perhaps far below 0F?) and most likely the thermostat isn't even programmed to do that. (Though I'm totally guessing on these latter two items.)

Until that point where it becomes less efficient, it stands to reason then that it is still more efficient to run the heat pump... hence why it's still confusing to my layman brain that it would stop running at all when temps are down in the 20s or teens. It's been consistently cold this week and I don't understand why there are hours of time (discontinuous, not consecutively) when the pump isn't running if aux heat is kicking in.
 
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Old 12-19-19, 05:43 PM
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Im cheap. I dont want my heat strips coming on at all. I set the drrop to 10f. That means heat strips will not come on until the t stat drops 10f below set point. I can set drrop from 1-15 degrees.

No the kicker, when it gets below 32 f the unit has a defrost feature. when it goes to defrost the heat strips kick on. dfrost mode last no longer then 10 minutes.

Now how I keep my home warm on cold nights here in SC?

Say its 15f out. I have t stat set for 72. heat pump cant keep up. so temp starts dropping on t stat... SLOWLY. It may het down to say 68f in the hose. But my defrost mode I have set for every 120 mins. ( Used to be set for 90 minutes, I changed it)

So if its below 32 f outside that heat pump will run defrost mode regardless. Well that defrost mode is enough that the heat strips com on during that max 10 min time and thats enough to bring my home back up to 72F. Then the cycle starts all over again.

This saves me $.

I thought about disabling the heat strips alltogther but the spouse dont want the cold blow of air when in defrost mode..

Some states you can lock out heat strips based on outdoor temp. This if they are wifi types.

I have a basic T^ honeywell pro. Works fine and does all I want.

I dont need the gimmicks of the IMO crappy nests and ecobees and such.

I set program, wake, away, home, and sleep settings. saves me the most $$$.

If someone comes home and the program is running they just turn up the temp and it sets a temp hold..

Geez whats your electric bill with those strips running 2 hours a day... sheesh. And mine are only 5kw strips.
 
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Old 12-21-19, 06:07 AM
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Not sure yet, because we just got all this installed a couple weeks ago.

I can tell you what our heating bills were last year after we bought this house before I realized we had a 40 year old all electric heat strip furnace... $600 in Dec/Jan/Feb.
 
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Old 12-21-19, 06:13 AM
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So I spoke with a rep from Sensi (thermostat company) because I found out when I have my heat pump cycle rate set to slow, it should only be a 2 degree swing at most, but I've been noticing around a 5 degree drop sometimes. The rep told me, when looking at my logs, that at times when stage one kicks on the temp drops by around 4-5 degrees in only a couple minutes. He looked over a 24 hour period and said that of the 5 times stage 1 kicked on, 3 of those times the rapid temp drop happened. By happenchance I then experienced, live, what he was talking about. We have our temp set to 69. The thermostat dropped to 68, and I heard the blower kick on and it showed it started the heating mode. A minute later the outside unit's fan came on. And within 3ish minutes the temp had dropped to 65. It slowly, slowly rose back up to 69 over the course of about half an hour... and I think at some point, perhaps 15-25 minutes in, the aux heat came on too. So SOMETHING has GOT to be wrong with this system.
 

Last edited by nightcabbge; 12-21-19 at 08:02 AM.
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Old 12-21-19, 10:05 AM
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Like the honeywell t stats there is something screwy built into the algoritums.

My Honeywell messes with the temps also.. My t stat will be at 70 and when I turn it up to 72 it will jump up to 72 in a very quick time. No way it heated the home 2 degrees in a matter of minutes. and what it does is its making it stay in 1st stage by doing this. somehow its trying to make me comfortable by crawling in 1st stage and keeping an even temp then cranking up on 2nd stage to satisfy a 2 degree swing and overheating the house an/ or short cycling.
 
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Old 12-21-19, 10:26 AM
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he rep told me, when looking at my logs, that at times when stage one kicks on the temp drops by around 4-5 degrees in only a couple minutes.
Sounds like your fan/heating system is in an unheated attic/basement.
Sounds like the thermostat is sitting close to, or above a register.
When the fan kicks on, it blows cold air directly only to thermostat.
That setup will give you huge temperature swings.

The thermostat dropped to 68, and I heard the blower kick on and it showed it started the heating mode. A minute later the outside unit's fan came on.
Normally the heat triggers first, then the fan triggers second. That sounds like the thermostat is wired/programmed with the fan and heat controls swapped.
Older thermostats triggered fan and heat source at the same time; a side effect was that registers would blow cold air for a minute or two until the heating unit came up to temperature.
Newer thermostats often delay the fan until the heating interchange is up to operating temperature; that way the system doesn't starts blowing air until the air is warmed.


SO-
When the house cools, the thermostat triggers.
The fan kicks on, and before the heat pump can warm up, cold air from attic/basement blows directly at the thermostat.
That cold air causes the thermostat to shift to the AUX heat cycle.
Then the heat actually comes on, and the heat jumps back up quickly.

If it's a "smart" thermostat, it then "learns" based on this bad data.
 
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Old 12-21-19, 10:54 AM
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Sounds like your fan/heating system is in an unheated attic/basement.
Sounds like the thermostat is sitting close to, or above a register.
When the fan kicks on, it blows cold air directly only to thermostat.
That setup will give you huge temperature swings.
Not exactly. It's in our basement, but there are vents down there that heat the area as it's partially finished. I'm not saying it's as warm as upstairs (I closed off one vent downstairs), but it's really not bad. But besides that... the return air vents are all coming from upstairs. While I can't guarantee the return air ducting is air tight everywhere, I'd assume the majority of the air it sucks in is from the heated upstairs, thus making the slighter cooler basement temp a moot point? The thermostat itself is not right beside any vents. It's in a hallway near the opening of an open concept dining/living room and the back bedrooms. No air hits it directly as it's kind of tucked away in there.

Normally the heat triggers first, then the fan triggers second. That sounds like the thermostat is wired/programmed with the fan and heat controls swapped.
Older thermostats triggered fan and heat source at the same time; a side effect was that registers would blow cold air for a minute or two until the heating unit came up to temperature.
Newer thermostats often delay the fan until the heating interchange is up to operating temperature; that way the system doesn't starts blowing air until the air is warmed.
This is interesting. I wasn't aware of what order things should fire in. I should check into this. However, even if it's doing exactly what you described for the reasons you describe, I still don't understand the 5 degrees in 5 minutes drop, because of that return air coming from upstairs (which should be around 68 degrees when it starts up according to the thermostat.)
 
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Old 12-21-19, 11:26 AM
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Yes example in heating mode I have my air handler set for an eff delay.


4. ENH:enhancedselection,providesa30secondon delay with no airflow followed by 150 seconds at 70% airflow, and no off delay for added comfort. This profile will minimize cold blow in heat pump operation and could enhance system efficiency.
 
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Old 12-21-19, 01:33 PM
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Originally Posted by nightcabbage
I'd assume the majority of the air it sucks in is from the heated upstairs, thus making the slighter cooler basement temp a moot point?
Nope. The system will push out the cool air that has accumulated in the basement ductwork.
Then, the system will pull air through all of those cool basement components; return ducts, (metal?) and the fan, and the heat-pump heat exchanger- which is at least 100 lbs of cold metal. That takes time to warm up.

However, even if it's doing exactly what you described for the reasons you describe, I still don't understand the 5 degrees in 5 minutes drop, because of that return air coming from upstairs (which should be around 68 degrees when it starts up according to the thermostat.)
First, if the basement is the only place in the house with air 5 degrees colder than average, then the air must be coming from the basement.

Second, warm air rises, cool air sinks. Unless the air is actively being circulated by a fan, the floor returns will suck in air that is cooler than the wall mounted thermostat indicates. In a basement with NO circulation, you might see a 1-degree per foot drop in temperature. In a house with circulating air, you might see a 1 degree per 2-foot drop in temperature.

When you heating system turns on, it blows cold basement air through the house.
Then is starts sucking in coldest floor air upstairs air through the house.

After three minutes of blowing cold air around (and messing with the "smart" thermostat's control logic) the heat pump kicks in.

However, by this time, the poor thermostat has panicked because the temperature has DROPPED as a result of turning the heat on.





Again, sounds like the
 
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Old 12-21-19, 01:59 PM
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If the basement is not used as living space and does not have its own registers then the system would not circulate the entire air contents of the basement throughout the house. Only the contents of the air ducts.

When the blowers start up, some air should be taken in via each of the return air ducts.
 
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Old 12-21-19, 02:10 PM
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Originally Posted by nightcabbage
Not exactly. It's in our basement, but there are vents down there that heat the area as it's partially finished. I'm not saying it's as warm as upstairs (I closed off one vent downstairs), but it's really not bad

Originally Posted by AllanJ
If the basement is not used as living space and does not have its own registers then the system would not circulate the entire air contents of the basement throughout the house.
.
THE BASEMENT IS COLD
I'm figuring that
A) the basement has hot air vents than can be closed
which implies
B) the basement has cold air returns. (which probably can't be closed.)
Which means that the system probably is sucking in cold basement air.

Even if no cold basement air is directly used, metal ductwork in a cold basement will still chill the air in the ducts, unless the ducts are insulated. Even WITH insulated ductwork, sitting in a cool/cold basement means that cold equipment will absorb the heat that is supposed to be warming the house, at least for the first few minutes.

RAISING THE HOUSE AIR 1 DEGREE FROM 68 to 69 WITH ELECTRIC HEAT CAN BE CHEAPER THAN RAISING OUTSIDE AIR 60 DEGREES FROM 39 DEGREES TO 69 DEGREES WITH A HEAT PUMP.
The solution here is simply algebra.
Skipping a bunch of variables- here are the basics-

1kW of power to heat pump = air at register* that is ~2x over OUTSIDE temperature
1kW of power to heat strip = air at register* that is ~+5 degrees over INSIDE temperature

*- temperature at register depends on compressor efficiency, tons/KW of heating, interior volume of house, outside air leakage into house, volume of air the ductwork can accomodate.
 

Last edited by Hal_S; 12-21-19 at 02:53 PM.
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Old 12-21-19, 02:51 PM
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I'm figuring that
A) the basement has hot air vents than can be closed
which implies
B) the basement has cold air returns. (which probably can't be closed.)
Which means that the system probably is sucking in cold basement air.

Even if no cold basement air is directly used, metal ductwork in a cold basement will still chill the air in the ducts, unless the ducts are insulated. Even WITH insulated ductwork, sitting in a cool/cold basement means that cold equipment will absorb the heat that is supposed to be warming the house, at least for the first few minutes.
Hmm. Well the majority of the return air vents upstairs are up high near the ceiling, so they would be sucking the warmest air from upstairs. (Though I do think there is one or two return air vents on the floor upstairs as well.) The return air ducting DOES go back into a dirt floor crawl space portion of the basement and runs a short ways to reach the back bedrooms' return vents, but that space's temp isn't that cold and there was box enclosure built around that ducting with insulation to boot. I took a closer look at ALL the return air ducting and can't find any return vents anywhere in the basement.

( What's funny is if any of these situations do exist and are causing this issue, the same scenario may in fact HELP during summer when the AC is on )

Thanks, this conversation has been very helpful in thinking about all the variables. I think it's lead me in another direction than where the Sensi rep was leading me. He was implying there may be something wrong with the reversing valve or heat pump itself.

There is one odd thing about all this though... when we had the old heat strip only furnace, I don't ever remember having this issue where the temp dropped when the blower turned on. (Perhaps that's because the heat strips heat up so quickly?)
 

Last edited by nightcabbge; 12-21-19 at 03:11 PM.
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Old 12-21-19, 03:15 PM
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Originally Posted by nightcabbage
There is one odd thing about all this though... when we had the old heat strip only furnace, I don't ever remember having this issue where the temp dropped when the blower turned on. (Perhaps that's because the heat strips heat up so quickly?)
That IS one benefit of electric heat. Instant heat.

The OTHER benefit of electric/gas/oil heat over a heat pump is more subtle.

Which is easier?
A) Take INSIDE AIR at 68 degrees and
-use electric heat to directly increase the air temperature by 1 degree to maintain 69 degrees.
or
B) Take OUTSIDE AIR at 19-39 degrees,
- use a heat pump to compress the air to increase the temperature by 50-to 30 degrees.
- accept losses from passing air through a heat exchanger to heat the working fluid
- accept the losses from circulating the working fluid
- accept the losses from passing air through another heat exchanger where the working fluid heats the air.
 
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Old 12-21-19, 03:20 PM
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Yeah, totally get it. I mean this all comes back to the efficiency equation, which has so many variables I won't try to tackle wrapping my head around all of it... at the end of the day though, my heat pump is going to bring down the costs quite a bit from my old electric heat strip furnace
 
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Old 12-21-19, 04:03 PM
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Any heating system will keep a perfectly insulated house warm. All it needs to do is make warm air warmer.

A heat pump basically doubles the outside air temperature, when it's cool, (single statge) and triples it when it's cold (two stage). That generally means 70-90 degree air at the grate, so a thermostat for a heat pump needs to be calibrated for a system that adds about 10-20 degrees to the house air temperature.

A gas/oil furnace is more brute-force, the air temperature at the grate is around 140 degrees So a thermostat for a furnace needs to be calibrated for a system that adds about 60-70 degrees to the house air temperature.
 
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Old 12-22-19, 06:45 AM
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Note: The heat pump does not compress large quantities of outside air for the purpose of raising the temperature of that air.

The heat pump system could not bring compressed outside air inside and release it because that air will cool back down to outside temperature again when released to uncompress. And also warm air originally inside commingled with the introduced outside air vented outside to relieve the pressure.

Instead only a small amount of gas (Freon) in a closed pipe loop is compressed, just as in a refrigerator or air conditioner. For the heat pump system he compressor is indoors and the Freon is compressed so much and the pipe diameters of the parts of the pipe loop are set so the Freon liquifies. Much more heat is given off (here, indoors) compared with compressing it (or any gas or plain air) but not liquifying it. The liquid Freon (sometimes ammonia is used instead) is sent outside through a thin pipe where it gets to an expansion chamber (just a fatter pipe in the loop). Here the Freon decompresses and turns back into a gas (evaporates; boils; sizzles) which gaseous state is normal at minus a few degrees F below zero and having space to expand into. Here the Freon absorbs heat (claims calories/BTU) from the outside in the process of evaporating, leaving the outside air in the vicinity of the heat pump unit colder still. The Freon gas returns inside via a medium fat pipe back to the compressor unit and the cycle repeats. Although the Freon gas might be at close to outside air temperature as it comes inside, it releases many calories/BTUs when compressed and liquified. No outside air is brought indoors for this process. (Outside air must be brought in in small quantities for health reasons via other means such as windows.)

If it is too cold outside, the walls of the expansion chamber (the evaporator coil) outside will get so cold (colder than outside air) that some of the Freon fails to evaporate. The lesser amount of Freon gas returning inside to the compresor means less heat is produced inside so at some point heat strips have to come on to provide enough heat inside. Defrosters are needed outside so the expansion chamber can at least return to outside temperature as opposed to becoming insulated with frost buildup and persisting at sub-outside temperature prolonging the aforementioned problem of insufficient Freon gas returning inside. At some point (in outside temperature) the runtime of the defrosters uses so much electricity that the net efficiency of the Freon loop is less compared with the heat pump shut down and indoor heat strips or baseboards relied upon for all of the heat. Also it does not make sense to keep the heat pump running if the re-liquified Freon has not attained the temperature of the room return air coming into the indoor unit to be reheated.
.
 

Last edited by AllanJ; 12-22-19 at 08:04 AM.
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Old 12-22-19, 07:59 AM
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I'm not savvy enough to digest all the posts. We have a heat pump and to keep our costs down...we only up the stat... one degree at a time so as to keep the heat strips from activating. You might check the wire coming out of the wall to the stat to see if there is a large hole letting cold air in ...to influence the stat.
 
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Old 01-08-20, 08:36 AM
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Any conclusions reached yet ? My thought is: were calculations made before installation...and is there one.... or two return air vents in the ceiling ?
 
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Old 01-08-20, 09:57 AM
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Which is easier?
A) Take INSIDE AIR at 68 degrees and
-use electric heat to dada dada ...
or
B) Take OUTSIDE AIR at 19-39 degrees,
- use a heat pump to dada dada ...
At moderately cold temperatures (generally above 40 degrees F outside) B is easier.
At extremely cold temperatures (generally below 0 degrees F outside) A is easier.
In between, B with occasional use of A takes place.

Some systems do not have a provision to block out B in extreme temperatures or the manufacturer's strategy is not to block out B. So the heat pump always runs when there is a call for heat.
 
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Old 01-13-20, 05:47 AM
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Air flow.

We have a small-ish 3 bedroom ranch... the front half of the floor plan more open concept in the kitchen/dining/living room area (low ceilings... just had a wall or two knocked out), then a hallway back to the 3 bedrooms/bathrooms. The 3 bedrooms all have return vents high in the wall. There's only 1 return vent I can find out in the main area, centralized on the floor (probably after they knocked out a wall during remodel.)

My thoughts are when air turns on, the 3 returns in the bedrooms cause a pressure difference that causes air to get sucked from the main area back through the hallway to the bedrooms. Guess where the thermostat is? In the hallway. It's not enough of a wind tunnel to notice on your skin, but it has to be happening.

I tried turning the blower on "circulate" 100% of the time... it's not a high speed, but does keep the air moving a bit. Once I kept that on all the time, I noticed: A) The temp drop was still there when stage one kicked on and the blower went into full speed, but only by about 1 degree instead of 4 to 5 B) The heat pump was turning on more frequently C) In my usage stats, I no longer see auxiliary heat kicking in. I attribute this to the idea that one or more of the rooms out in the open area drop temp more quickly and there's a pretty major temp equilibrium issue compared to the bedrooms/hall that keeps toasty longer. Once I stared circulating air, that colder air got put back into the back of the house sooner, dropping the temp there more in lockstep... and quicker, which attributes to heat kicking on more often.

So I guess this is good news, because I found the issue and it's mostly solvable, at least the issue with the temp drop that was causing auxiliary heat to kick on when it didn't really have to. I don't think I have an issue leaving my blower fan on circulate all the time at the slower speed... but I dunno, maybe that will negate some of the electric savings I was worried about anyway. I have no idea what it will do to my electric bill if I suddenly keep the blower on, even at low speed, for the other 75% of the day. If I find this is not ideal in some way, my only other way to fix this issue would be to relocate the thermostat into the main area where it gets colder faster, and where the temp wouldn't suddenly drop because of the suction through the house. I mean, I could also put in more return vents out there, but given the layout that looks like it would be a pain.
 
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Old 01-13-20, 10:43 AM
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Originally Posted by nightcabbage
It's not enough of a wind tunnel to notice on your skin,
A match, candle, or candle-lighter will show airflow VERY accurately.

Could add a ceiling fan to mix the air, or a small high efficiency fan to circulate the air.

If the open-concept area gets direct sun, you can avoid the pool of cool air and create some passive circulation by adding a "happy cat rug"- Lay out a dark rug/runner along the path the sun takes across floor (for each window). The sun will warm up the dark rug (and attract any cat in the house). Cool air at floor-level is warmed by the rug and rises, drawing in replacement cool air. This gives you some passive circulation, AND warms that lowest layer of cold air that you notice if you walk bare-foot..


I would be interested to see what changes if you keep the bedrooms/bathroom doors closed, versus leaving them open.
 

Last edited by Hal_S; 01-13-20 at 11:03 AM.
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