Heat Pumps

[Buford T. Justice]

Hey crew, I am doing a large scale remodel of my house & garage. I have replaced all windows & siding adding r-board. I am on propane right now but am seriously considering going all electric replacing the furnace thats 15 years old and going to a air heat pump (not ground source) as I don't have the funds. For those in the know can you give me any pros & cons of going to this? This is a new area for me as I am HVAC challenged.

 

[rieferman]

This is just my layman's terms understanding:

- we have a normal gas furnace that heats/cools our first floor
- we have an electric heat pump that heats/cools our 2nd and 3rd stories
- heat pump works sort of like a window air conditioner, but one that can work in both temperature directions. Ever stand outside a window AC unit and feel the hot air coming out? Imagine capturing that heat during the winter time and running it into your house. That's basically how it works. Google has much better definitions, that's just a plain english explanation.
- main drawback with heat pump is that if it gets extremely cold (lower than, say, 32 degrees F) on a frequent basis, the supplemental heat (basically toaster oven type of coils) must kick on, as the heat pump reaction with the outside air cannot provide enough temperature boost. This supplemental heat is far less efficient and more expensive to run.
- I'm in PA and my supplemental heat kicks on about 2-3 days per year. So it's fine for us.

 

[930dreamer]

We have a heat pump in TX. It gets cold enough in winter that the full heat comes on below 32. The thing I don't like about the heat pump is the air is warm, not hot. You don't have the comfortable feeling, just warm. I don't know if I would buy another one or not. 930

 

[CraigFL]

I've had heat pumps for over 27 years. In the beginning, they weren't as efficient and had to be transferred over to other heat when it got cold. Now, with increased efficiencies and higher heating costs overall for all fuels, they still are effective at very low temperatures. I don't know that most installers even set them right or keep up on the changing energy cost conditions. Theoretically, you need to know the temperature that your heatpump costs more than the alternative heat source you would be using. A lot of installers set the transfer to when the COP = 1. COP is coefficient of performance, which means the pont where the power in = the heating power out. COP varies with the outdoor temperature for air-air exchangers getting closer to 1 as the temperature drops. By using geothermal, the COP is less dependant on the outdoor temperature. COP = 1, would be the point of transfer if electrical heat were the alternative heat source but not necessarily for natural gas, propane or oil.

With the very high efficiency units of today, I suspect that you will be able to run your heatpump down to zero outside temperatures.

 

[scooterseats]

I agree with 930dreamer, the heat pumps heat by moving large quantities of warm air. If you have large rooms by the time the air reaches your skin it feels cool. The gas heat or even electric resistance heat allows you to actually feel warm even when the air is moving. This is true even with the new high efficiency models, they just do not provide hot air at the registers. I personally, would never install another heat pump, even in a relatively warmer climate.

 

[enrgeezone]

I do install these systems here in NJ I am not a big fan of just installing straight heatpumps I will however install them with gas and oil fired furnaces...then you have the ability to run the heatpump when the temp allows and when the need for backup heat comes I have the gas or oil furnace kick in...... saves the electric bill keeps the wife and kids warm..and also gives you the ability to use whatever cost less at the time gas, oil or elec... there are heatpumps on the market that will run well into the teens if not zero, but they are made from small indepent. co. that have not been so successful infact many have had many name changes and still remain in business... lord help ya if you need a part for future repairs!..... In many states that have a calm winter season I see no reason not to use these systems....but if winter weather is harsh in you neck of the woods I would have to say look for another source of heat.....and if you have only had gas or oil before you will never be satasified with a heatpump.....

 

[Buford T. Justice]

Thanks for the replies. I'm going to do some hard research. There's great rebates right now for doing these 1/3rd off the cost from power co. plus fed tax credit

 

[Salem747]

As mentioned a heat pump is really just a supplement to your furnace in most normal climates. If you live in southern texas/arizona/NM or something it may be enough by itself. As mentioned it is a "low grade" heat, meaning it is warm and it runs all the time. Not like your furnace that blows hottish air for a short time and then shuts off. We were in Kamloops BC and we had the furnace set to take over at 6 Celsius otherwise the heat pump was running steady.

A really important benefit of it is that it not only saves energy in the "sort of" cold but it is your central air in the summer too!

 

[OccupantRJ]

NC here. I have a heat pump, my power bill is averaged, 1200 sq ft house full of electronics, dishwasher, water heater, etc, temp kept at 72 winter, 74 summer, and my bill is $159 year-round. It sometimes gets down to 14 F here in January, but winter is usually in the low 30's. Summer can hit 100 on rare occasion. Heat pump works for me. I have gas logs for power outages.

RJ

 

[bonneyman]

I'd say if your house is already set up for gas, stick with it. When the flame burns, you get hot air. With a heat pump, the colder it is outside, the less heat you get inside. Kinda opposite of what you really need, see?
Heat pumps are really made for those houses that have A/C and electric heat strips, and want to upgrade. Fossil fuel furnaces are much more comfortable when you need the heat, but, to convert to them (if your house isn't already set up for it) can be expensive. You gotta run the gas line, add fresh air inlets and run exhaust piping, etc.
Heat pumps are more "efficient" than strip heat, but just remember the compressor runs in the winter in a H.P. That a big amp draw whenever the thing runs. Your locale will determine if it's viable.
For me in AZ, we don't get that cold, and the sun is out ALOT - even in winter. So, our heat needs are not too great. Hence, H.P.s work well here. But I wouldn't want one in North dakota!

 

[pseudorealityx]

Any heat pump should be installed with some sort of additional heat. Typically this is an electric strip heater, but can also be done with a furnace as has been mentioned here in the thread.

During cold weather, the outside condenser coil will freeze up, and the unit will switch into a defrost mode, which in reality is "cooling mode". During this time, it will not provide heat, so you have to have some additional heat.

The benefit of a heat pump is that it's very efficient compared to strip heat. At least 3 times more efficient in cooler days, and still over 2 times as efficient as it gets colder down in the teens. Gas vs. Electric is far too varied cost wise geographically to compare, so do some homework to decide which is better for you.

 

[konnerbelly]

Heat pumps warm the air indoors by pulling heat from the outside air by attempting to cool it. Heat pumps can be quite efficient and are a great way to go if you live in a place with poor solar access and no natural gas. over 50% of the country has no natural gas and solar is best in certain geographies where you also have a roof line with good direction and no shading.. So when you need warmth the most, the unit attempts to cool down the outside air which is already quite low, so it's hard work for the unit which if not operating at top efficiency may show reduced performance..

 

[pseudorealityx]

Heat pumps warm the air indoors by pulling heat from the outside air by attempting to cool it. Heat pumps can be quite efficient and are a great way to go if you live in a place with poor solar access and no natural gas. over 50% of the country has no natural gas and solar is best in certain geographies where you also have a roof line with good direction and no shading.. So when you need warmth the most, the unit attempts to cool down the outside air which is already quite low, so it's hard work for the unit which if not operating at top efficiency may show reduced performance..

Residential grade heat pumps still have COP's over 2 at 17 degrees F. That's for baseline 13 SEER units.

Solar is not a viable heating source for the majority of Americans.

 

[danski0224]

Hey crew, I am doing a large scale remodel of my house & garage. I have replaced all windows & siding adding r-board. I am on propane right now but am seriously considering going all electric replacing the furnace thats 15 years old and going to a air heat pump (not ground source) as I don't have the funds. For those in the know can you give me any pros & cons of going to this? This is a new area for me as I am HVAC challenged.

I have a dual fuel system. That is a gas furnace and a heat pump (air to air).

It works great. I can heat with the heat pump only down to 25*F.

Heat pump heat is a little different than fossil fuel as the vent temperature is a bit cooler. Also, as the outdoor temperature gets closer to the balance point, the system will stay on longer. The long run time and cooler vent temperatures compared to traditional fossil fuel heat are the big differences.

You need a variable speed blower (ECM motor) so the costs of running the circulation fan more doesn't cost an arm and a leg.

I have an oversized 2 stage heat pump which allows me to have a lower balance point. The duct system needs to be capable of moving this additional air. My system would work better if this was true for me, but I can't change the ducts buried in the slab.

It runs on 1st stage cooling, so the air conditioner performance is not sacrificed.

My heating bill for November 2009 was less than $60- all heat pump. I am near Chicago, IL.

All top shelf, 2 stage equipment isn't cheap.

I would recommend it if the budget allows.

Sizing for heating in a heating climate won't work so well in the cooling season. Stick with the proper size air conditioner if 2 stage stuff is out of your budget. This option is well worth the small upcharge.

A proper heat load needs to be calculated to determine the theoretical balance point.

Actual utility costs will determine the economic balance point.

A heat pump with electric backup operates a bit differently than a dual fuel (fossil fuel) system. You may have both heat pump and electric backup on at the same time near the balance point. That doesn't happen with fossil fuel.

My furnace does not fully cycle on during the defrost cycle- the interval is too short.

Note- heat pumps must be correctly charged to function properly.

 

[walrus]

I've heard good things about these guys, I don't have one but have talked to guys who have installed them.

http://www.gotohallowell.com/

Another company is Nyle kiln in Maine. The guy who developed the unit for Hallowell used to work for Nyle