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heat pump system question #4650969
01/30/18 10:58 AM
01/30/18 10:58 AM
Joined: Nov 2009
Posts: 4,943
Houston, Texas
motor_oil_madman Online content OP
motor_oil_madman  Online Content OP
Joined: Nov 2009
Posts: 4,943
Houston, Texas
Is the condenser outside supposed to run the whole time the system is on? I've never seen mine turn on it's always the neighbors. I've always lived in houses with a gas furnace, so I'm not familiar with how an electric one works. I did read somewhere that instead of the condenser removing heat like in the summer that it reverses and puts heat back in. At first I thought the neighbor had the air conditioner on when it was like 35 degrees outside. lol


2007.5 dodge cummins 6.7 liter. Chevron Delo400 15w40. 7000 mile or 250-300hr intervals.

Re: heat pump system question [Re: motor_oil_madman] #4650981
01/30/18 11:07 AM
01/30/18 11:07 AM
Joined: May 2012
Posts: 1,364
The land of USA-made Subies!
SubieRubyRoo Offline
SubieRubyRoo  Offline
Joined: May 2012
Posts: 1,364
The land of USA-made Subies!
It shouldn't run all the time, but yes, that is the method. It "moves" heat through the refrigerant into the house in the winter, and out of the house in the summer. As long as the outdoor temp is above the min temp of the system (generally 5*F, more or less), the heat pump can typically be more energy-efficient than a gas or electric furnace. It's all about the COP (coefficient of performance) at the outside temps that should drive the decision on what heat source to use.

Re: heat pump system question [Re: motor_oil_madman] #4650996
01/30/18 11:16 AM
01/30/18 11:16 AM
Joined: Aug 2003
Posts: 12,901
NE,Ohio
Rand Offline
Rand  Offline
Joined: Aug 2003
Posts: 12,901
NE,Ohio
I would hesitate to say a heat pump is more efficient(cost effective really) than a natural gas furnace.

Now vs propane.. way better.

In my experience heat pump can easily be 3:1 or more efficient than electric heating.

Heat pump is very nice for warmer climates.

Not so nice if you have to turn on aux. oil or electric heat.


2019 Jeep Cherokee Trailhawk 2.0T
Re: heat pump system question [Re: motor_oil_madman] #4651002
01/30/18 11:22 AM
01/30/18 11:22 AM
Joined: Nov 2009
Posts: 4,943
Houston, Texas
motor_oil_madman Online content OP
motor_oil_madman  Online Content OP
Joined: Nov 2009
Posts: 4,943
Houston, Texas
I guess it's a heat pump system. I have central ac, just thought it was weird at first when the outside ac units were running in the winter. I never really researched it.


2007.5 dodge cummins 6.7 liter. Chevron Delo400 15w40. 7000 mile or 250-300hr intervals.

Re: heat pump system question [Re: motor_oil_madman] #4651021
01/30/18 11:49 AM
01/30/18 11:49 AM
Joined: Jan 2013
Posts: 1,843
Texas
WyrTwister Offline
WyrTwister  Offline
Joined: Jan 2013
Posts: 1,843
Texas
At one time , dual fuel HP's were available that used a gas fires furnace as emergency / auxiliary heat .

This might be the best of both worlds if you have gas available .

Not sure of the cost of propane vs the cost of electric resistance heat ?

If you live in a climate where it rarely gets below , say , 25F , a HP would be worth considering .


Wyr
God bless
Re: heat pump system question [Re: motor_oil_madman] #4651025
01/30/18 11:51 AM
01/30/18 11:51 AM
Joined: Jan 2012
Posts: 431
Phoenix, AZ
azjake Offline
azjake  Offline
Joined: Jan 2012
Posts: 431
Phoenix, AZ
Originally Posted By: motor_oil_madman
Is the condenser outside supposed to run the whole time the system is on? I've never seen mine turn on it's always the neighbors. I've always lived in houses with a gas furnace, so I'm not familiar with how an electric one works. I did read somewhere that instead of the condenser removing heat like in the summer that it reverses and puts heat back in. At first I thought the neighbor had the air conditioner on when it was like 35 degrees outside. lol

It depends on your system. I have a heatpump with an electric heat strip in the air handler unit so the condenser does NOT turn on for heat. My previous home did not have the heat strip so the condenser did turn on for heat.

The reason why the electric strip is better is at or below freezing the fins in the outside unit can develop frost and the unit has to go through a defrost cycle before it can function and produce heat. The tech who installed my current system said the one or two times a winter here in Phoenix when it dips below freezing they get swamped with calls from customers who complain they are not getting heat. This is why the systems they install now all have the heat strip.


2015 Nissan Murano SL
Re: heat pump system question [Re: motor_oil_madman] #4651050
01/30/18 12:20 PM
01/30/18 12:20 PM
Joined: Nov 2009
Posts: 4,943
Houston, Texas
motor_oil_madman Online content OP
motor_oil_madman  Online Content OP
Joined: Nov 2009
Posts: 4,943
Houston, Texas
The one thing I can't figure out is how to switch it over to a.c. mode. If that's the case I want to run the air conditioner periodically to keep everything lubed up.


2007.5 dodge cummins 6.7 liter. Chevron Delo400 15w40. 7000 mile or 250-300hr intervals.

Re: heat pump system question [Re: motor_oil_madman] #4651053
01/30/18 12:22 PM
01/30/18 12:22 PM
Joined: Nov 2009
Posts: 4,943
Houston, Texas
motor_oil_madman Online content OP
motor_oil_madman  Online Content OP
Joined: Nov 2009
Posts: 4,943
Houston, Texas
I remember times where I was younger and my dad turned the a.c. on for the first time in 6 months and it sounded like the fan motor was seized up for a moment outside.

Last edited by motor_oil_madman; 01/30/18 12:22 PM.

2007.5 dodge cummins 6.7 liter. Chevron Delo400 15w40. 7000 mile or 250-300hr intervals.

Re: heat pump system question [Re: motor_oil_madman] #4651093
01/30/18 01:17 PM
01/30/18 01:17 PM
Joined: May 2013
Posts: 133
Peace valley, Missouri
Fitter30 Offline
Fitter30  Offline
Joined: May 2013
Posts: 133
Peace valley, Missouri
You do not want to run as in the winter unless its above 70*. Heat pumps are ok to run in heating that's what their made for. In cooling the pressures that they run in cooling will trash the compressor unless the unit is set up for low ambient temps. On your thermostat it will have a heat, cool and emergency heat setting if it's a heat pump. Look at you tube videos under heat pump operation.

Re: heat pump system question [Re: azjake] #4651097
01/30/18 01:18 PM
01/30/18 01:18 PM
Joined: Mar 2004
Posts: 20,758
Upstate NY
Donald Offline
Donald  Offline
Joined: Mar 2004
Posts: 20,758
Upstate NY
Originally Posted By: azjake
Originally Posted By: motor_oil_madman
Is the condenser outside supposed to run the whole time the system is on? I've never seen mine turn on it's always the neighbors. I've always lived in houses with a gas furnace, so I'm not familiar with how an electric one works. I did read somewhere that instead of the condenser removing heat like in the summer that it reverses and puts heat back in. At first I thought the neighbor had the air conditioner on when it was like 35 degrees outside. lol

It depends on your system. I have a heatpump with an electric heat strip in the air handler unit so the condenser does NOT turn on for heat. My previous home did not have the heat strip so the condenser did turn on for heat.

The reason why the electric strip is better is at or below freezing the fins in the outside unit can develop frost and the unit has to go through a defrost cycle before it can function and produce heat. The tech who installed my current system said the one or two times a winter here in Phoenix when it dips below freezing they get swamped with calls from customers who complain they are not getting heat. This is why the systems they install now all have the heat strip.


The heat pumps go backwards in defrost mode (back to being an A/C) to deal with the frost. They use the electric coils to warm the air in that mode so you do not get cold air into the house during defrost.


2015 Subaru Forester 2.5 engine/CVT
2015 Ford F250 w/Powerstroke
2016 Subaru Crosstrek CVT (wife's)
Re: heat pump system question [Re: motor_oil_madman] #4651104
01/30/18 01:22 PM
01/30/18 01:22 PM
Joined: Dec 2016
Posts: 453
Indiana
5AcresAndAFool Offline
5AcresAndAFool  Offline
Joined: Dec 2016
Posts: 453
Indiana
It all depends on how its set up. If you have natural gas it is unlikely IMHO a heat pump is worth it since natural gas is cheaper than dirt right now. A heat pump may be more efficient than a natural gas furnace at warmer temps, say above 40, but not necessarily cheaper.

Some heat pumps are set up to lock out under a certain temperature.

Now we Have either electric or propane as our heating choices.

We have a higher efficiency heat pump, It makes sense to run ours to -10F due to the efficiency of the unit, and our use of costly electric heat strips as backup.

So if its over -10f and the thermostat is calling for heat, the outside unit is running. When the unit goes into defrost mode, the outside units fan shuts off and the compressor continues to run. (basically it reverts back to being an air conditioning unit, it will remove heat from the house to warm and defrost the outside coils).

On our unit it will not defrost when the outside temperature is over 50F because it is not needed.

Now the heat strips will kick on when the unit goes into defrost (otherwise you would have cold air blowing out of your registers) OR when the heat pump cannot keep up due to the outside temperature being lower. This is called the balance point.

Our balance point is roughly 25F. Anything lower than that supplemental heat is required. It Depends on the wind, if we have basement registers open ect.

Now you can put your thermostat in "emergency heat" mode. Basically this turns off the outside unit, no matter the conditions, and will strictly run your heat strips in the furnace, or propane/gas burner. This is intended if you have an issue with your outside unit.


Heat from a heat pump is very efficient. You are not burning any fuel to create heat when just the heat pump is running, you are just paying to move the heat indoors.

Like I tell my wife, our heat is free, we just have to pay to get it in the house.




Last edited by 5AcresAndAFool; 01/30/18 01:24 PM.
Re: heat pump system question [Re: motor_oil_madman] #4651109
01/30/18 01:29 PM
01/30/18 01:29 PM
Joined: Dec 2006
Posts: 7,654
Toronto, Canada
KrisZ Offline
KrisZ  Offline
Joined: Dec 2006
Posts: 7,654
Toronto, Canada
Originally Posted By: motor_oil_madman
The one thing I can't figure out is how to switch it over to a.c. mode. If that's the case I want to run the air conditioner periodically to keep everything lubed up.


Unlike automotive AC systems, home AC units should not be run in winter and there is nothing to lube up. The risk to zero reword is quite great.
Heat pumps have heated compressors, that's why they can operate in winter.


2015 Dodge Grand Caravan-27k miles.
2006 Mazda 3-163k miles
Re: heat pump system question [Re: motor_oil_madman] #4651119
01/30/18 01:34 PM
01/30/18 01:34 PM
Joined: Dec 2016
Posts: 453
Indiana
5AcresAndAFool Offline
5AcresAndAFool  Offline
Joined: Dec 2016
Posts: 453
Indiana
I will add that since I do not want the heat strips to kick on unless absolutely necessary, and I dont care if we get cold air during defrost mode, that I have made changes to the control scheme of the heat strips.

Not many people would do this, But I am a special kind as my wife tells me...

But she admits it has saved us alot. We ran one winter on the factory control scheme, and after my modifications, it saved us rough 25%, at the slight expense of comfort, but not really that noticeable.

Re: heat pump system question [Re: motor_oil_madman] #4651130
01/30/18 01:45 PM
01/30/18 01:45 PM
Joined: Jul 2014
Posts: 119
North TEXAS
oldoak2000 Offline
oldoak2000  Offline
Joined: Jul 2014
Posts: 119
North TEXAS
Yes, a heatpump will run loonger as temps drop.

The compressor will actually use FEWER amps at lower temps - most don't realize this.

Inside the compressor, all the moving parts are bathed in oil, so there is technically no additional wear for long run times - fan motors however will eventually wear with long run times . . .

Re: heat pump system question [Re: oldoak2000] #4651158
01/30/18 02:27 PM
01/30/18 02:27 PM
Joined: Dec 2016
Posts: 453
Indiana
5AcresAndAFool Offline
5AcresAndAFool  Offline
Joined: Dec 2016
Posts: 453
Indiana
Originally Posted By: oldoak2000
Yes, a heatpump will run loonger as temps drop.

The compressor will actually use FEWER amps at lower temps - most don't realize this.

Inside the compressor, all the moving parts are bathed in oil, so there is technically no additional wear for long run times - fan motors however will eventually wear with long run times . . .


Yes, good point!

At 0 degrees out heatpump uses a little under 3 kwh an hour. At 55 degrees that goes up to around 4.5

The compressor does not have to work as hard as the temps cool down because your line pressure also drops.

Ours has run for weeks straight in the winter with no ill effects. Its almost 10 years old.

I LOVE our heatpump.

I was a slave to the woodstove one winter here. Never again.

I took the woodstove off our homeowners and the amount saved on insurance nearly pays for the worst month of heating costs.

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