Hello:

I have 2 Trane Air Source Heat Pumps - one in the living room & one in the bedroom. My house is north of Montreal.

I also have electric baseboard heaters throughout the house.

Am I suppose to turn the heat pumps off at a certain outside temperature.

I ask this because I was told that at a certain temperature there is no point to use them as their electricity consumption will be as much as my baseboards and running them will just 'wear them out' more quickly.

Thanks,

Rob.

That is correct. At some point, the input will be close to output and you will be working them hard for nothing.

Didn't your heating professional tell you what that temp was?

Newer heat pumps are more efficient than older ones.

Thanks ICFHybrid.

It is a DIY situation - I'll consult the manual.

I'll consult the manual.

I would be interested in what Trane says it is. These Daikins will get you into below zero (F) handily and Mitsubishis reportedly get you down to about -15F without breaking a sweat. My "father's heat pump" went into resistance heat at about 32F, if I remember correctly.

running them will just 'wear them out' more quickly.

On the other hand, even running them at a COP of 1 will keep the compressor warm. That might have some value in either preventing a crankcase heater from running or in reducing cold startup wear.

Many have outdoor temp monitoring to shut them off below x-temp

Posted By ICFHybrid on 25 Dec 2013 04:31 AM

I'll consult the manual.

I would be interested in what Trane says it is. These Daikins will get you into below zero (F) handily and Mitsubishis reportedly get you down to about -15F without breaking a sweat. My "father's heat pump" went into resistance heat at about 32F, if I remember correctly.

Hi ICFHybrid:

I found some info at http://www.trane.cl/catalogos/Split_muro_%20alta_eficiencia%20_inverter/Catalogo_Tecnico.pdf

It seems the operating temperature is:   Heat: (-15)C ≤ T ≤ 24C   Cool: 18C ≤ T ≤ 48C   or,  Heat: (-5)F ≤ T ≤ 75.2F   Cool: 64.4F ≤ T ≤ 118.4F

It doesn't seem to say that it will automagically stop when the temperature is below or above the operating temps.

Rob.

So, does this mean that I should run my heat pumps as long as the outside temperature is warmer than the minimum?

Is there some sort of electronic gizmo to detect the outside temperature and turn off the heat pumps at a specific temperature?

Thanks,

Rob.

A thermostat and a relay would do that.

wiring diagram will tell you if you have a low temp lockout

Older than? I have no idea about this science but my Carrier airHP is 23yrs old and seems fine. But its 30F BELOW freezing here in Canada so why no winter covers in the hardware stores? I would like an audible alarm to tell me when the elements cut in and it seems to me there should also be an outside thermostat to switch the outside part off at 15F below freezing? Also without an air input and output temperature guide how can anyone utilize these air heat pumps effectively?? Seems that these installation people only do half a job, or am I wildly wrong?

Seems that these installation people only do half a job, or am I wildly wrong?

Depends on your installer of course, but you're not wildly wrong. Seems like homeowners would have a modicum of responsibility to know what they are getting and how it works, but maybe that is asking too much of an average person any more.

I am looking seriously at the ASHP units that heat to -25c (-13f) and while its been a lot colder than that for weeks now and I realize that they would, at worst, produce heat at a COP of 1/1 (using the heat strip)

it would be no worse than running the back-up heat (also electric) which runs at no better than 1/1. So its a wash below -25c...

ASHP and baseboards/elec furnace all perform at a COP of 1/1.

I wouldn't want a winter cover on the unit since that would prevent its operation (or damage it) when the temps rose above -25c and the heat pump became active again.