Which Is More Efficient Central Air-Conditioning Or A Heat Pump?

This Question Was Posted Below By Anonymous 1/13/2005 09:46:25 AM

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Here it is...which is more efficient central air-conditioning or a heat pump? I live in Tucson, Arizona so heating is really not a big issue. I think I have turned the furnace on twice since October. But hey AC is a biggie. I am looking at a 2300 sq ft home with R-19 for walls and R-50 in the roof. I am trying to figure out the most efficient way to cool it. Any thoughts?
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The Department of Energy requires that all air conditioning and heating equipment manufacturers rate the efficiency of their equipment. These ratings are known as SEER or Seasonal Energy Efficiency Rating for air conditioning and HSPF or Heating Seasonal Performance Factor for heat pumps. Heat pumps use both ratings because they heat in winter and cool in the summer.

A heat pump is basically an air conditioning system with a few components added to enable it to change the way that refrigerant is pumped through the system.

To put in the simplest terms, the indoor section (air handler) removes heat from the air in the building as the air passes over the evaporator which is located inside the air handler. The outside section (condensing unit) rejects this heat from the building in summer.

One of the extra components that a heat pump has is a reversing valve and this valve changes the flow of the refrigerant through the system so that the outside section becomes the evaporator and the indoor section becomes the condensor.

Which is more efficient central air-conditioning or a heat pump?

A heat pump with a rating of 10 SEER would operate with the same efficiency as an air conditioner with a 10 SEER rating. The higher the SEER rating, the more efficient the air conditioning system will be.

I would have to say that I don't think you need a heat pump for your particular situation. You can have electric heat installed in the air handler which will easily meet your needs. If you required heat on a regular basis, then I would reccomend a heat pump.

Based on prices where I live if you choose to go with a heat pump your initial investment will be about 30% more for a heat pump than a central air conditioning system of equal capacity. Considering the amount of time you actually require heat, the cost of using electric heat would be very small. I don't know energy costs for Tuson but I would expect that it would take at least ten years to recover the extra expense of selecting a heat pump over an air conditioning system.

In a nutshell a heat pump with a 10 SEER rating and an air conditioner with a 10 SEER rating will do the exact same job. Since you are interested in air conditioning, a heat pump would not be the best choice for you.

A Tip For Selecting A Contractor

One of the biggest problems people encounter when purchasing air conditioning or heating equipment is their contractor doesn’t do an accurate load calculation.

If you get three quotes and each estimates that you need a different size system (3.5 Ton, 4 Ton, 4.5Ton). The person who gathers the most information about your home, such as R-value of insulation in your walls and attic, is probably more conscientious and accurate in his assessment.

If a contractor comes to look at your home and in five minutes tells you what size system you require try to get another price. To do an accurate load calculation takes more than a five minute walk through. From what I have seen far too many contractors use this inaccurate method.