Gas swimming pool heaters are powered either by propane or natural gas. As such, either a propane storage tank or a natural gas hook-up is required to operate one of these heaters. Make plumbing connections in and out of the heater and make a power connection from the timeclock or nearby outlet.

Operating similar to a gas-fired home furnace or hot water heater, a burner tray on the bottom heats the air inside the fire box and transfers that heat to water circulating through the heat exchanger. Gas pool heaters heat water quickly and effectively, but it's important to ensure that your heater suits the size of your pool in order to get the best heating performance and results.

Pros and Cons of Gas Pool Heaters

• • Low Initial Cost
• • Fastest Heat Gain
• • Not Weather Dependent
• • Most Costly to Operate
• • Most Temperamental

Gas pool heaters for swimming pools can sell for anywhere in the range of $1000 to $3000, for heaters with energy output of 100K-500K BTU.

Gas pool heaters are the fastest way to heat a pool or spa. They can raise water temperature in the pool by 2-5 degrees per hour, depending on the size of the heater, and whether or not the pool is covered. Gas heaters are ideal for pools or spas heated for short periods of time and for pools heated only for weekends, or occasional use.

Gas heaters are the only type unaffected by weather or outside temperature. They can operate even in freezing temperatures, unlike heat pumps. Gas heaters also work well during rainy or cloudy days, unlike solar pool heaters.

Gas pool heaters are the most expensive type of pool heater to operate, costing the average pool owner $100 to $400 per month, depending on size of the pool, thermostat setting, how cold the air temperature is, and whether or not the pool is covered.

Sizing a gas heater for inground pools is done by first matching pool heater BTU output to pool size in gallons. Or approximately 100K BTU’s for every 10,000 gallons of pool water. For inground pools less than 20,000 gallons, small gas heaters like the Raypak 206K BTU output are suitable. Pools up to 30,000 gallons should look at the Pentair 300K BTU or higher, and pools over 50,000 gallons should look at the Hayward 500K BTU. Pools in very windy or colder areas, or those that don’t use a pool cover should consider installing one size larger.

Sizing a gas heater for above ground pools is done by first matching pool heater BTU output to pool size in gallons. For pools under 10,000 gallons, small gas heaters like the Hayward 100K$) BTU output are suitable. Pools up to 15,000 gallons should look at the Pentair 125K BTU or higher, and 20,000 gallon above ground pools should look at the Raypak 150K BTU. Pools in very windy or colder areas, or those that don’t use a pool cover should consider installing one size larger.

1. Surface area - The main job of any pool heater is to heat the pool water at a faster rate than heat is being lost from the surface of the swimming pool. Once the ideal temperature has been reached, your pool heater only needs to run enough to compensate for the heat that escapes from the surface of the water. Therefore, we strongly suggest using a quality Solar Blanket in conjunction with your pool heater (or with any piece of pool water heating equipment for that matter), in order to maximize efficiency.

2. Temperature rise - The temperature rise of your pool water is a calculation of your desired water temperature minus the average ambient air temperature. The desired water temperature is simply the final temperature you'd like your pool water to reach. The average ambient air temperature is the average daily outdoor air temperature and should be figured on the basis of the coldest month you plan on using your pool. For instance if you live in an area where the average outdoor air temperature in May (the month you would like to start using your pool) is 60 degrees and your desired water temperature is 80 degrees, your temperature rise would be 20 degrees (80 - 60).

3. Heater efficiency - Pool heater efficiency is provided by the manufacturer, and is expressed as a percentage that represents the amount of energy a pool heater transfers to the water for each unit of energy (BTU) used to generate that heat. The US Department of Energy has mandated that all pool heaters have an efficiency rating of at least 78%. So, as an example, a 300,000 BTU pool heater with an efficiency of 85% would produce 255,000 BTU/hr. Solar Heating Systems for Your Inground Pool

Installation of a gas pool heater involves placing the unit on a sturdy fire-proof base, outdoors, with adequate ventilation surrounding. Connect the plumbing after the filter, in and out of the heater. Connect power to operate the safety circuits, and connect the heater to the bonding grid. A gas contractor is recommended to make the gas connection into the heater, from the natural gas meter, or from a propane gas tank. Gas heaters can be installed indoors, but only with proper venting. Gas heaters emit carbon monoxide, which can be hazardous if venting is done incorrectly or not maintained. A carbon monoxide detector is recommended for any indoor pool heater installation.

Gas heaters may require more maintenance than other pool heater types. They can last 10-20 years with good care and timely repairs.

Gas pool heaters can be the best choice for heating inground pools in cold weather, areas of very high electricity cost, or when fast heating is desired, for example heating only on weekends, or heating an attached spa up to 104 degrees F. Properly sized gas heaters can be used year around, in any climate in North America.

Heat pump swimming pool heaters require a dedicated electrical circuit with a breaker size of 30 to 60 amps, depending on the heater size. As such, pool heat pumps often require an electrician for correct and safe hookup.

Electric or heat pump pool heaters for pools incorporate aspects of solar heating in that they absorb warmth from the surrounding air into a liquid refrigerant, compress the liquid to create more heat, and transfer the heat to the pool water. Outside temperatures greater than 50 degrees F are required for operation, and the warmer the air is, the less operation time required.

Pros and Cons of Pool Heat Pumps

• • Low Cost to Operate
• • Ecofriendly, Zero Emission
• • Reliable, Safe Operation
• • Slow to Heat
• • High Initial Cost

Pool heat pumps have a very low cost to operate, as compared to gas pool heaters. The average pool owner may spend $60-$200 per month on electricity to power the heat pump fan and compressor, depending on how cold the air temperature is, and whether or not the pool is covered. Those in high energy cost areas will also spend more with an electric heat pump. Heat pumps are close to 100% efficient, as compared to 80% for most gas pool heaters.

A heat pump can be considered more eco-friendly than a gas pool heater. Although there is an environmental cost of consuming the power generated to run a heat pump, the heat pump does not directly burn fossil fuels, nor emit carbon monoxide, like a gas pool heater.

Pool heat pumps tend to be more reliable and require less repair and maintenance as they age, as compared to gas heaters. Heat pumps have a simpler design, partly due to required safety controls for gas-fired heaters. As such, heat pumps may also have the advantage of being a safer appliance to have in the backyard.

One drawback to heat pumps is that they are slow to heat, and typically add only 2-5 degrees F, per day, depending on the outside air temperature, size of the heater, and whether or not you use a pool cover. Compare this to a gas heater, which can heat 2-5 degrees per hour, and you see the advantage that gas heaters have for intermittent heating. Consistent heating however, is no problem for a pool heat pump; after a 3-5 day warm-up period, it maintains warm water efficiently and effectively.

Another drawback to a pool heat pump is the initial purchase cost, which is the highest among all pool heater types, and at least twice the cost of an equivalently sized gas pool heater. Inground pool heat pumps range in cost from $2700-$4250, for heaters with energy output of 100-140K BTU. Above ground pool heat pumps range in cost from $1650-$2850, for heaters with energy output of 55-115K BTU.

Sizing a heat pump for inground pools is done by first matching pool heater BTU output to pool size in gallons. For pools of up to 20,000 gallons, small heat pumps like the Hayward 95K BTU output are suitable. Pools up to 30,000 gallons should look at the AquaCal 120K BTU or higher, and 40,000 gallon inground pools should look at models like the Pentair 140K BTU. Pools in very windy or colder areas, or those that don’t use a pool cover should consider installing one size larger.

Sizing a heat pump for above ground pools is done by first matching pool heater BTU output to pool size in gallons. For pools under 10,000 gallons, small heat pumps like the TropiCal T55 are suitable. Pools up to 15,000 gallons should look at the AquaPro 77K BTU or higher, and 20,000 gallon above ground pools should look at models like the TropiCal 115K BTU. Pools in very windy or colder areas, or those that don’t use a pool cover should consider installing one size larger.

Installation of a heat pump pool heater involves placing the unit on a sturdy base, with good air flow. A sunny area is best but not required. The plumbing is connected to send pool water in and out of the heater. An electrician is recommended, to properly wire the heater and connect it to the bonding grid.

Installation cost can differ depending on the location of the pool heater. A natural gas heater requires a gas line from the gas meter, and a pool heat pump needs a buried electrical line from the main breaker box. Depending on the distance to the pool heater, the gas line or the electric line may be more expensive to install. If you already have electrical conduit and 100 amp service to your inground pool pump, you may have the available ampacity to add another large breaker (30-60 Amps), to power a heat pump.

Heat pump pool heaters may require periodic maintenance in order to keep the moving parts in good shape. However, when properly maintained, electric pool heaters have an excellent lifespan of 10-20 years.

Heat pump pool heaters provide an excellent option for pool owners who want to use solar energy to heat their pool yet cannot accommodate a solar heater on their property or live in a region of frequent cloudy weather. Properly sized heat pumps can be used for year around pool heating in southern states, or can be used to provide warm pool water from April-November for most of North America.

Solar swimming pool heaters rely entirely on the sun's energy to heat pool water. As water circulates through the solar panels, heat from the sun's rays is transferred into the water. While some solar swimming pool heaters are designed to be set up on rooftops or mounted on wooden racks, other models can be installed on the ground.

Pros and Cons of Solar Pool Heaters

• • Low Initial Cost
• • Zero Cost to Operate
• • Ecofriendly, Zero Emissions
• • Entirely Weather Dependent
• • Lower Heat Gain

Solar pool heaters for pools are less expensive to buy than gas-fired heaters or pool heat pumps, but if you want to add 15-20 degrees F to the water, you need to use enough solar panels to equal at least 50% of the pool surface area. For most inground pools, a good solar system will cost $1500-$2000, still one of the cheapest methods of heating a pool. For most above ground pools, a good solar system will cost $250-$750, still one of the cheapest methods of heating a pool.

With no cost to operate the solar panels, other than the cost of running the filter pump, which you are may be doing anyway, solar pool heating is the least costly way to heat an inground pool.

In terms of environmental friendliness, solar pool heating is the clear leader. No fossil fuels, no emissions, no fuels or refrigerants needed, only the sun; a renewable resource. Solar panels, made entirely of thermoplastics, are also more easily recycled than other pool heater types.

The largest drawback to solar pool heaters is that they are entirely dependent on sunny weather. They can still heat the pool on warm and partly cloudy days, but with cool and rainy weather solar heaters lose heat, and they don’t work at all during the night.

Another disadvantage attributed to solar pool heaters is lower overall heat gain. However, solar systems are modular, and the more panels you have, the greater heat you can add to the water. If you have a sunny southern facing location to place enough panels to equal 50-80% of your pool surface water, and you get at 6-8 hours of daily unobstructed sun - you can match the heat output of a gas heater or heat pump, adding 20-30 degrees F to the pool. A small solar system however, or one with only 4-6 hours of daily unobstructed sun may only gain 5-10 degrees, which is easily lost with a few cloudy days.

What does the Ideal Solar Pool Heater System look like?

A southern facing single story roof that’s at least 20’ long, with unobstructed sun, for at least 6 hours daily would be best. Even better if it is close to the pool pump and filter, so that long plumbing runs aren’t required. Another good location would be a free standing, triangular shaped rack, built of slotted angle bracing or lumber framing with a plywood deck. These can be placed up against a fence, on the sunny side. Or a pergola or pool cabana can be used, if the roof has a 10' width.

How many solar panels are needed?

The more panels you have, the more heat you can harvest. Swimming pools in ideal solar conditions should use at least 50% of the pool surface area, For example, an 18x36’ pool has a surface area of 648 square feet. 50% of that would be 324 feet of solar panel surface area, or about 4 of the 4’x20’ panels, which are 80 sq ft each. In less than ideal conditions, such as an east/west orientation, or partial sun obstruction from trees or houses, a higher multiplier of 70-80% can be used, to compensate for panels that receive less direct continuous sun. Remember that the sun is always moving across the sky as our seasons change. A large tree that doesn’t block the sun during May could be a real shade tree in September. Also you need enough solar panel surface area to make a reasonable difference. An undersized solar system will only produce 5-10 degrees of heat.

Can solar panels be installed on separate roofs?

Yes, you can install separate sets of panels, in series, on different facing roof sections for instance. The water will run through the first panel set, exit and then enter the second set of panels.

Do I need a booster pump?

No, most solar systems operate just fine on the volume of water pushed from the existing filter pump. Even installing panels on a second story roof is no problem for most inground pool pumps. There are instances where a larger filter pump or booster pumps are recommended, but these are not the norm.

Installing a Solar Pool Heater System

Not too difficult to do, most in ground pool solar heaters can be installed in one day. Above ground solar heaters can be installed in less than an hour. Location is most important, so after figuring out if you will install on a roof, fence or deck, the panels can be installed. A southern orientation is best in the US, and installing at a 45 degree angle will absorb more heat. The solar panels can be roof mounted in a few hours, secured to protect them from winds. Then you connect plumbing from the return line, after the filter, to the panels on the roof, securing vertical pipes to the wall. The final step is usually wall mounting the solar controller and installing the temperature sensors.

Care and Maintenance of a Solar Pool Heating System

Solar heating systems require very little maintenance. It is important to keep your pool water balanced and your filter in good operating condition. Since the water that goes into the solar collector comes straight from the filter, if there is anything that bypasses the filter, it can potentially clog the solar collector.

Improper pH and calcium hardness can cause mineral build up in the solar collectors. Low pH or high levels of chlorine can cause the plastic to become brittle. If you have very high calcium hardness levels in your pool, use a scale inhibitor on a regular basis to prevent mineral build up in the solar collector.

Although rare, splits or damage to the tubes in a roof mounted solar pool heater can be repaired with an inserted plastic sleeve. This works similar to a stint placed in a blocked artery. One of the greatest things about solar pool heaters is their reliability, and simple design.

How long do solar pool heaters last?

Ironically, the summer sun will eventually attack a solar pool heater, causing it to become brittle and breakdown. Most polypropylene solar heater panels will last at least 10 years in the hottest parts of the country, and longer in the more temperate regions. More durable solar panels made of rubber can last 20 years or more before the material begins to weaken.

Winterizing a Solar Heating System

Most solar heating systems have drain plugs to allow the water to drain out of the panels. They are often installed at a slight tilting angle to facilitate drain down. For proper winterization, it’s a good idea to blow air through the collector to remove any trapped water in the panels or on top of a vertically mounted check valve. Winterizing is also a good opportunity to inspect the collector panel for damage and inspect the mountings; to be sure the solar panels are secure and ready for the winter.

Solar panels for pools are typically manually operated by turning a valve to direct water into the solar panels. When sunny conditions wane, you must remember to turn the solar panels off again, or the water will radiantly cool as it passes through the cold panels. To avoid this, and to enjoy the convenience of setting a desired temperature, solar pool heaters can be controlled with the installation of a Solar Controller. These automatically turn a valve to send water to the solar panels when sensors signal that solar heating conditions are good, and bypass the solar panels when conditions are poor, or when the pre-set temperature is reached.

Sizing a solar heater for pools is done by measuring your pool’s total surface area, by multiplying the length x width. Buy enough solar panels to equal 50-80% of your pool surface area. For example, a 20’x40’ pool would have 800 sq. ft. of surface area, and would require 400-650 sq. ft. of solar panel surface area, for best results. The more solar panels you add; the more heat you get. It’s a good idea to oversize solar pool heaters, for windy areas, uncovered pools, or to compensate for bad weather. For above ground pools, consider modular units like the SunCoil Solar Dome.

Installation of a pool solar heater involves placing the solar panels in an area of unobstructed sun, cutting the return line after the filter, and redirecting the water through the solar panels. Valves are used to direct the water to the panels, and also to bypass the panels. For best results, a solar controller can be mounted, with sensor and valve actuator connected, to maintain a consistent temperature more easily. Solar pool heater installation is much less complicated than other methods, and the only one that is truly DIY friendly and fully achievable by most pool owners.

Solar pool heaters require no maintenance and will typically last for 10 to 15 years, before ironically, the plastic degrades from the sun’s solar rays.

Solar heaters are powerfully fast heaters in direct summer sun, but lose effectiveness in cooler, off-season months, when the sun moves lower through the sky. As such, they are not appropriate for year round pool heating, with exception to far southern regions of North America. For most northern regions, properly sized solar heaters can maintain warm water from May-October.