Common Approaches to Heating Your Home: Part III

This is Part III of a 3 part Series.  Part 1 is here; Part 2 is here.

Hybrid Heat Pump

This choice is sometimes referred to as a Dual Fuel Heat Pump. It utilized both gas and electricity to heat your home. The efficiency of a heat pump is because at most heating temperatures, it moves heat from outside to inside.

Think about your refrigerator. When the inside warms up to 40•, the food risks going bad, so the fridge finds the heat and pumps in out.  Your food stays refrigerated. At 40• outside, a heat pump can find heat and efficiently bring it inside. This costs less than consuming natural gas, propane or electricity to produce heat in a furnace.

At much lower temperatures, a heat pump will need a boost to maintain the heat. This is an electric resistance strip heater. It is used in emergency and back up situations.

A hybrid heat pump uses a conventional furnace for emergency and back up. This is less expensive than electric resistance heat.

Your Choice

In our climate zone; I believe the rank of these approaches should be:

  1. Geothermal
  2. Hybrid Heat Pump
  3. Traditional Furnace / AC
  4. Air Source Heat Pump

This ranking is based primarily on Efficiency Issues with overall comfort issues second.  This rank considers only long term operating costs. It does not consider capital costs (installation).

There are two primary considerations for all of the installation and ultimately comfort issues.

  • The home must be ready for an efficient heating/ac equipment installation.  This means the thermal envelope must be sealed and well insulated. Your thermal envelope is defined as the basement walls, or crawl space walls, the wall above ground, the ceiling.
  • The calculations for equipment size, and selection must be done professionally. The use of a recognized computer program authorized by the ACCA (Air Conditioning Contractors of America); showing the Manual J calculations of the improved home for determining heat loads; and the Manual S calculations to select the equipment. You may wish to have your ductwork reviewed and perhaps resized.  This would call for calculations with ACCA Manual D.

The choice to go with Geothermal or ASHP would mean very little gas usage, only the hot water heater. That could be converted to electric with the ASHP. With a Geothermal Unit, you could utilize a system of hot water that is known as ‘de-superheating’.  It uses otherwise wasted heat from the Heat Pump unit to heat water.

The capital costs of these units in the Wichita area are estimated at:

  • Geothermal:               15-25,000+ (open or closed loop)
  • ASHP:                           7 -12,000
  • Hybrid Heat Pump:    7 – 12,000
  • Furnace/AC                 7 -12,000

The Geothermal unit is considered to be a renewable energy source and carries a 30% tax credit, with no limit.  It is available through 2016. Before giving much thought to a geothermal system, a homeowner should discuss the location with a driller to determine the depth of wells and the quality of the water. Do not install an open loop (also known as pump and dump) without a water quality test in your possession. Consider a closed loop system, if there are any concerns about water quality or the amount of water needed. Drought is a reality in Kansas. A well designed and installed geothermal system will last many years.  I have audited homes with systems that are 30+ years old. I have audited homes with failed systems, of 10 years or less, that were not well planned.

Comfort Note: Conventional Furnaces blow heated air into the duct work at temperatures from 105 – 150; depending and the design factors of the furnace.  If you have come in from the cold and stood neat the supply register of a forced air furnace, you feel the heat.  A heat pump type of heating does not create heat to be blown into the duct work at these high temperatures, a heat pump typically blows air into the ducts at 85 – 95 degrees.  This change can cause people to not like a heat pump; air source or ground source. A hybrid heat pump would provide the same range as a furnace with lower outside temperatures.

Please post your questions below as comments!

Leave a Reply

Your email address will not be published. Required fields are marked *