Geothermal Q&A

Geothermal Heat Pumps: Questions You Should Ask About a New Heating and Cooling System.

Regardless of the type of heating and cooling system you may be considering for your home or business, there are specific questions you should ask the dealer/ installer. These questions deal with finding out the actual efficiency of the system, any operating limitations it may have, and the bottom line of operating costs. The answers here are meant as a guide for what you should try to find out with your questions.

Q: What is the Btuh [kW] size of the heat pump or furnace that’s being proposed?
A: Heating systems are designed to provide specific amounts of heat energy per hour. The term “Btuh” [kW] refers to how much heat can be produced by the unit. Before you can know what size system you’ll need, you must have a heat loss/heat gain calculation done on your home. From that, an accurate determination can be made on the size of the heating/cooling system. Many fossil fuel furnaces are substantially oversized for home heating requirements, resulting in increased operating costs.

Q: Is the efficiency rating actual or just a manufacturer’s average?
A: All types of heating and cooling systems have a rated efficiency. Fossil fuel furnaces have a percentage efficiency rating. Natural gas, propane and fuel oil furnaces have efficiency ratings based on laboratory conditions. To get an accurate installed efficiency rating, factors such as flue gas heat losses, cycling losses caused by oversizing, blower fan electrical usage, etc., must be included. Air conditioners are normally rated in SEER (Seasonal Energy Efficiency Ratio). SEER and EER (Energy Efficiency Ratio) cannot be directly compared without the use of software.

Geothermal heat pumps, as well as all other types of heat pumps, have efficiencies rated according to their Coefficient of Performance or COP for heating and EER for cooling. It’s a scientific way of determining how much energy the system produces versus how much it uses.

Most geothermal heat pumps systems have COPs of 3.5 – 5.0.That means for every one unit of energy used to power the system, 3.5 to 5 units are supplied as heat. Whereas a fossil fuel furnace may be 80-90 percent efficient, a geothermal heat pump is about 450 percent efficient. Some geothermal heat pump manufacturers and electric utilities use software to accurately determine the operating efficiency of a system for your home. Software like ClimateMaster GeoDesigner allows comparisons in dollars to avoid the confusion of the various rating systems.

Q: Will the minimum entering water temperature have an affect on which heat pump I buy?
A: Yes. If you have an open-loop system, your entering water temperatures (EWTs) may range from the 70s°F [20s°C] in the southern United States to the 40s°F [single digits, °C] in Canada. All heat pumps can handle temperatures in the moderate to warm ranges. A closed-loop system, on the other hand, may encounter EWTs below freezing. Not all ground-source heat pumps will operate at those low temperatures. It’s important for you to know what EWTs your heat pump will handle.

Q: Are the dealer and loop installers qualified?
A: Don’t be afraid to ask for references from dealers. A reputable dealer won’t hesitate to give you names and numbers to call to confirm his capabilities.The same applies to the loop installer.

Q: Will open- or closed-loop be best for you?
A: That depends on several factors, as stated earlier. A dealer should be willing to install what’s best for you, not for him.

Q: Will the loop joints be heat fused?
A: The only acceptable method for joining buried sections of the special pipe used for closed loop systems is heat fusion. Any other method will eventually result in the failure of the loop.

Q: How long is the payback period for your ground- source heat pump system?
A: To figure this accurately, you must know how much per year you’ll save in energy costs with a ground-source system, and the difference between it and a traditional heating system and central air conditioner. As an example: if you’ll save $700 per year with a ground-source system and the costs difference is $2,000, your payback would be less than three years.

Tampa Geothermal Installation

Q: If a home has ceiling cable heat or baseboard heat, do air ducts need to be installed?
A: Not always. It may be desirable to install ground- source heat pump room units. For some small homes, one room unit would provide most of the heating and cooling needs. Ceiling cable or baseboard units could then be used for supplemental heat.

Q: Can I use a geothermal heat pump for radiant floor heating (warm floors)?
A: Yes. Water-to-Water heat pumps heat water instead of air. The principle is the same as far as loop piping is concerned. Warm water is circulated through the floor to heat the home.