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Heat Pumps

Heat pumps on the Energy Wise program give you the most economical heat of any heating system.  The heat pump is over one-and-one half to three times more efficient for heating, and on the dual fuel Energy Wise rate, you will have the lowest energy costs for heating.  Rebates are available for the installation of air source heat pumps if installed by a quality installer.  Ground source heat pumps are rebated based on the size installed.

Energy Wise heating with a heat pump is billed at $0.0652 for all heating energy.  All sub-meters have a $2.50 monthly fee.

Heat pumps used for cooling, and air conditioners, on the Energy Wise program, allow you to cool your home at the cycled air conditioning rate.  Cooling systems are cycled on and off during peak load times.  This helps control energy use but it also keeps you comfortable.

The cycled cooling Energy Wise program gives you cooling at a $0.0782/kWh rate.  In some cases, an annual credit applied to your electrical bill is a cheaper way for you to have cycled air and help reduce the peak demand.

Air-Source Heat Pumps - How They Work

A heat pump's refrigeration system consists of a compressor and two coils made of copper tubing (one indoors and one outside), which are surrounded by aluminum fins to aid heat transfer. In heating mode, liquid refrigerant in the outside coils extracts heat from the air and evaporates into a gas. The indoor coils release heat from the refrigerant as it condenses back into a liquid. A reversing valve, near the compressor, can change the direction of the refrigerant flow for cooling as well as for defrosting the outdoor coils in winter. 

The efficiency and performance of today's air-source heat pumps is a result of technical advances such as the following:

  • Thermostatic expansion valves for more precise control of the refrigerant flow to the indoor coil
  • Variable speed blowers, which are more efficient and can compensate for some of the adverse effects of restricted ducts, dirty filters, and dirty coils
  • Improved coil design
  • Improved electric motor and two-speed compressor designs
  • Copper tubing, grooved inside to increase surface area

Selecting a Heat Pump

Every residential heat pump sold in this country has an EnergyGuide label, which displays the heat pump's heating and cooling efficiency performance rating, comparing it to other available makes and models.

Heating efficiency for air-source electric heat pumps is indicated by the heating season performance factor (HSPF), which is the total space heating required during the heating season, expressed in Btu, divided by the total electrical energy consumed by the heat pump system during the same season, expressed in watt-hours. 

Cooling efficiency is indicated by the seasonal energy efficiency ratio (SEER), which is the total heat removed from the conditioned space during the annual cooling season, expressed in Btu, divided by the total electrical energy consumed by the heat pump during the same season, expressed in watt-hours. 

The HSPF rates both the efficiency of the compressor and the electric-resistance elements. 

The SEER rates a heat pump's cooling efficiency. In general, the higher the SEER, the higher the cost. However, the energy savings can return the higher initial investment several times during the heat pump's life. A new central heat pump replacing a vintage unit will use much less energy, cutting air-conditioning costs substantially. 

To choose an air-source electric heat pump, look for the ENERGY STAR┬« label. In warmer climates, SEER is more important than HSPF. In colder climates, focus on getting the highest HSPF feasible. 

These are some other factors to consider when choosing and installing air-source heat pumps:

  • Select a heat pump with a demand-defrost control. This will minimize the defrost cycles, thereby reducing supplementary and heat pump energy use. 
  • Fans and compressors make noise. Locate the outdoor unit away from windows and adjacent buildings, and select a heat pump with an outdoor sound rating of 7.6 bels or lower. You can also reduce this noise by mounting the unit on a noise-absorbing base. 
  • The location of the outdoor unit may affect its efficiency. Outdoor units should be protected from high winds, which can cause defrosting problems. You can strategically place a bush or a fence upwind of the coils to block the unit from high winds. 

 

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