RSPEC - Heat Pump Pool Heaters

Swimming pools are big energy consumers. Pool owner/ operators spend billions of dollars annually to heat the nation's pools. Much of this energy is often wasted and can be saved with proper management. Wasting energy also contributes to our growing air quality problem.

RSPEC is a national program that asks you to consider measures to Reduce Swimming Pool Energy Costs.

Why do pools cost so much to heat? Pools lose energy in a variety of ways, but evaporation is by far the largest source of energy loss for swimming pools. When compared to evaporation, all other losses are small.

The reason evaporation has such an impact is that evaporating water requires tremendous amounts of energy. For every gallon of water that evaporates out of a pool, it takes with it over 8500 Btus, and a typical pool loses 1 to 1½ inches of water a week. For a 1000 square foot pool, an inch of water equals 625 gallons or over 50 therms of natural gas every week. (A therm is equal to 100,000 Btus. Because of all the energy required to evaporate a gallon of water, evaporation turns out to be 70% of the heat loss from a pool.

The first step in selecting a pool heating system is to minimize the heat loss from the pool, which in the case of pools is primarily evaporation.

How do you stop evaporation?… Use a pool cover. Pool covers are the most effective way to reduce pool heating costs. By covering the pool when it is not in use, you can greatly reduce your pool heating costs. See the RSPEC fact sheet on Pool Covers for additional information.

The decision on how warm to keep the pool is up to the individual owner. The temperature recommended by the American Red Cross for competitive swimming is 78° F. This comfort level also coincides with good fuel savings.

However, this may be too cool for young children and the elderly who may require a temperature of 80° F or higher. The typical range for pools is 78°- 82° F. Keep in mind, however, that the energy consumption for each degree rise in temperature will cost from 10-30% more in energy costs depending on your location. In warmer climates the percentage is higher due to the relatively low cost of heating a pool at 78° F.

The following chart shows costs of heating pools in different parts of the country to different temperatures. The figures are based on a 1000 square foot outdoor pool heated by a heat pump pool heater with an average COP of 5.0 at $.085/kwh. The pool season also varies by location and the pool is uncovered for 8 hours per day.

Location	Season	Temperature
Location	Season	78°	80°	82°
Miami	1/1-12/31	$1100	$1460	$1845
w/ cover	1/1-12/31	$215	$300	$410
Phoenix	3/1-10/31	$680	$875	$1090
w/ cover	3/1-10/31	$45	$85	$125
Dallas	4/1-10/31	$760	$970	$1240
w/ cover	4/1-10/31	$90	$140	$205
Atlanta	4/1-10/31	$840	$1110	$1425
w/ cover	4/1-10/31	$155	$205	$290
Los Angeles	5/1-10/31	$950	$1210	$1485
w/ cover	5/1-10/31	$85	$155	$240
Kansas City	5/1-10/31	$715	$935	$1185
w/ cover	5/1-10/31	$145	$205	$270
New York	5/1-9/30	$740	$975	$1220
w/ cover	5/1-9/30	$105	$150	$200
Chicago	5/1-9/30	$810	$1035	$1270
w/ cover	5/1-9/30	$105	$150	$195
Denver	5/1-8/31	$875	$1055	$1245
w/ cover	5/1-8/31	$70	$100	$150
Boston	5/1-8/31	$875	$1075	$1280
w/ cover	5/1-8/31	$120	$165	$235
Minneapolis	6/1-9/30	$660	$850	$1040
w/ cover	6/1-9/30	$100	$125	$190
San Fran	6/1-8/31	$800	$950	$1110
w/ cover	6/1-8/31	$95	$165	$240
Seattle	6/1-8/31	$770	$900	$1035
w/ cover	6/1-8/31	$150	$215	$280

Today an emerging method of heating pools is the heat pump pool heater. A heat pump's efficiency is dependent on the outside temperature and since pools are usually used during warm and mild weather, heat pumps are a very efficient method of heating pools.

Heat pumps do not generate heat, they simply capture it and move it from one place to another. Below is a diagram that shows how heat pumps operate.

How efficient is a heat pump? That's not an easy question to answer. Heat pumps don't have a simple efficiency number to work with. Their efficiency is measured by Coefficient of Performance (COP).

Just like other heating options, heat pumps can have low efficiencies or high efficiencies. Their COP can range from 3.0-7.0. The higher the number the more efficient the heat pump. What this means is that for every unit of electricity that you put in to run the compressor, you get 3-7 units of heat out of the heat pump. These COPs are usually determined by testing the unit with an outdoor temperature of 80°F and a pool temperature of 80°F. But there is no standard test, so you should be aware of this. The higher efficiency units usually use scroll compressors versus the reciprocal compressors of the standard units.

Pool heaters are mainly sized according to the surface area of the pool and the difference between the pool and average air temperatures. The heating load is also affected by other factors such as wind exposure, humidity levels and cool night temperatures. Pools located in areas with higher average wind speeds at the pool surface, lower humidity, and cool nights will require a larger heater. You should consult with a trained professional on determining the size you need.

The first step in determining if a heat pump pool heater is the choice for you is to determine the efficiency of your existing heater. If it's an electric resistance heater, the efficiency is 100%. If its a gas heater, use the chart below. Some pool heaters include this information on the name plate.

The following chart shows what you can save with a heat pump compared to a gas or electric resistance heater for every $1000 in current annual pool heating costs by installing a high efficiency heat pump pool heater. These calculations are based on an electric cost of $.085/kwh and a natural gas cost of $.50/ccf. A seasonal average COP of 5.0 was used to determine the savings.

Current Htr Eff	Cost w/ 5.0 COP	Annual Savings
Gas Pool Heater
55%	$550	$450
60%	$600	$400
65%	$650	$350
70%	$700	$300
75%	$750	$250
80%	$800	$200
85%	$850	$150
90%	$900	$100
95%	$950	$50
Electric Pool Heater
100%	$200	$800

Efficiency is one consideration, but you should also consider the reputation of the manufacturer and/or dealer who will install your heater. Get some references of satisfied customers and call the Better Business Bureau if you don't have anything to go on. Also be sure to ask for and read all warranties before making you decision

How much could YOU save by installing a high efficiency heat pump pool heater? Download a free copy of the Department of Energy's Energy Smart Pools software from this web site and run some calculations. Just run an analysis with the as is conditions and then run another analysis with the new heat pump.

You will also find additional fact sheets and information on saving energy in pools at the RSPEC web site or by calling the Energy Efficiency and Renewable Energy Clearinghouse at 800-DOE-EREC.

If you know someone else who's interested in saving money on their pool operation, feel free to pass along a copy of this fact sheet to them. Reproduction and distribution of this piece or any of the RSPEC fact sheets or software is not restricted, but actually encouraged. RSPEC can make a difference!