Facts about Pool Heating

Written on:March 9, 2024
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Facts about Pool Heating


Considering today’s high fuel costs, does it make sense for me to heat my pool?
The answer is yes – if you want to enjoy comfortable swimming at your own convenience. One of the reasons for owning a pool is being able to swim when you want to. As for cost, that’s up to you. You really can control fuel consumption and waste simply by taking advantage of the suggestions made on this page.

What guidelines should be followed in heating our pool?
Taking into consideration the need to conserve energy and to minimize fuel consumption, any unnecessary pool heating should be avoided. You are the best judge of the kind of use you want out of your pool. Use of your pool for recreation, exercise, therapy or just general enjoyment obviously will require heating it. Your pool won’t contribute to your health or pleasure unless it’s warm enough to swim in comfortably- and when you want to swim. Actually, using your home pool can be far less wasteful of energy and cost you less in fuel than driving to distant resort and vacation areas for away-from-home recreation.

How warm should I keep my pool?
That depends entirely on you, of course. The temperature recommended for recreational and competitive sports swimming by the American Red Cross and many swimming coaches is 78 degrees F. This comfort level coincides with good fuel conservation practice, too.

Young children, the elderly and others often need 80 degrees F or warmer water, however, and hydrotherapy calls for warmer water, too.

Although 78 degrees F to 82 degrees F takes in about everyone, how warm you should keep your pool actually depends on personal preference.

Obviously, a heated pool means more swimming. How much more?
You’re right. The sun alone usually can’t keep your pool water at that comfort minimum of 78 degrees F. By having a heater to warm your water you can add substantially to the daily use of your pool-and you can also extend the so-called swimming “season”.

How much more swimming? From early morning to late evening, even with air temperatures of 65 degrees or lower – if your pool is warm.

You can stretch your pool season by twice in most areas and even longer in other areas by having a heated pool. The usual 2-month season in Detroit, for example, can be doubled, and in Los Angeles the season can be more than tripled. In New York, Chicago and Philadelphia – double the season or better.

If we don’t heat our pool, how much swimming season can we expect?
It depends on your climate – and whether you use a pool cover. Without a Solar cover you’ll probably have a season of only one or two months in most areas and perhaps three months or a little more with a cover.

During those months when the average mean temperature in your area is high enough to heat your pool water to a minimum 75 degrees F – and hold it there – you will be able to boost this temperature to 78 degrees F or more if you use a good Solar cover and keep it on your pool when the pool is not in use.

Pools that are not covered can lose 4 degrees F to 5 degrees F overnight in most parts of the country. With a cover, you can reduce that heat loss by 50% or more. So without a heater you should be able to use your pool in the afternoons and early evenings in the warmest part of the season.

Remember that besides air temperature you must consider such variables as wind speed and humidity, both of which affect the rate of heat loss from the pool. If your pool is not covered, protect it from breezes as best you can with walls, covered fences, shrubs, cabanas, etc.

Do we need to heat our pool when the weather’s hot?
Again, it depends on you and your personal pool temperature preference. It also depends on the climate in your area – and whether you use a good quality cover to conserve energy and heat.

Even using a cover, you’ll probably have to heat your pool a little, particularly during summer cool spells and for morning and evening swimming.

In Cleveland, Pittsburgh and Seattle, for example, even the July – August average mean temperatures are usually below 75 degrees F and moderate heating would be essential for comfortable swimming. By contrast, average mean temperatures in summer are high and sustained. But “real” weather has a tendency to vary a lot from the mean, so it’s a good idea to rely on a heater to brighten up the cool spots and lengthen the swimming season.

What are the costs involved in heating a pool?
First, there is the initial or one-time cost of the heater you select and its hook-up or installation charge. Second, there is the monthly fuel cost, which varies with the type of heating system you buy, the use of your pool, the pool water temperature you prefer and other variables.

Third, there is the matter of annual or semi-annual maintenance and service.

Operating costs can be kept to a minimum by installing an efficient, properly sized heater; using a good quality pool cover; and, of course, keeping your filter clean and your heating and filtering system well maintained.

What are the health benefits of heating my pool?
A pool that is properly heated and properly used can contribute to and help safeguard health. Doctors and physical therapists regard swimming as one of the most beneficial of cardiovascular exercises. It is an exercise that nearly everyone can do safely, while running and jogging are impossible for many elderly people and those who suffer from arthritis and muscular diseases.

By heating your pool, you make it possible to engage more often in swimming exercise because you extend the hours and the season your pool may be used.

A heated pool prevents chilling and the problems caused by the loss of too much body heat. Pediatricians say very young children are especially susceptible to various respiratory infections which may result from repeated chilling – and this is also true of elderly swimmers.

A heated pool is a must for therapeutic benefits and when swimming for relaxation. Doctors and Red Cross swimming experts recommend pool temperatures of from 78 degrees F for recreation and competitive sports swimming, to 90 degrees F or more for certain physical therapy patients.

We hear a lot of praise for the pool cover. Is it merited?
Most certainly. A good insulating pool cover can reduce heat loss by 50% or more, depending on your location and climate.

A pool that is uncovered can lose up to 5 degrees F overnight; a good cover can cut that loss by half.

Used at night or whenever your pool is not in use, the pool cover can help save fuel costs by cutting heat loss regardless of the type of heating you utilize. And it can even make an unheated pool more swimmable by helping to retain the sun’s energy that naturally heats the pool during the daytime.

A pool cover stops water evaporation when it is in place. It isn’t the water loss that’s the big consideration here-it’s the heat loss. Every gallon of water that evaporates from a pool takes with it 6000 BTU’s of heat in the process – and a typical uncovered pool loses 1 to 1½ inches of water a week through evaporation. For a 20 by 40 foot pool, an inch of water amounts to 500 gallons – roughly, a heat loss of more than 30 therms every seven days. (A therm is equal to 100,000 BTU’s).

Besides stopping heat loss, a cover saves on pool chemicals, too, by keeping them from evaporating with the water.

What types of heating are available to us?
Several – from the sun itself to gas-fired, electric and elaborate solar heating systems.

The most widely used type is the direct fired natural gas heater because of its low cost, reliability, ease of operation and the wide availability of natural gas. In areas where natural gas is not available, heater models can be furnished equipped to use LP gas or propane gas.

Solar heating ranges from simple “passive” solar – the familiar pool cover that absorbs and transmits some of the sun’s energy to pool water – to “active” solar heating systems.

Used alone, the passive heating technique merely serves to help keep pool temperatures at existing levels by retaining natural solar heat and preventing its loss. It cannot add heat to build up water temperature beyond what the sun supplies. Active solar uses traditional pool motors to move water from the pool through a system of solar collector panels for heating by the sun. This increases the amount of solar heat added to the pool.

Why not go strictly solar? After all, it’s free.
Not exactly – in fact, not by long shot. An adequate solar pool heating system will cost substantially more initially than fuel-fired heaters. It can add 25% to 50% to the cost of building a pool.

Solar systems have definite limitations. To begin with, they require sufficient area in which to install large collector panels, usually on a roof or deck overhang near the pool. Even in an area like southern California, the total solar collector area needs to be at least equal to 75% (100 % is better) of the pool surface area. This means that if you have a 20 x 40 pool you should have a 20 x 40 collector area available for best results.

You probably would have to increase the size of your electric pump – or provide a second pump – to deliver the pool water to the collector panels. And the pump would have to work almost continuously during most sunlight hours. This means your pump would be running during “peak load” periods when the utilities’ generating plants are often taxed to capacity – and when they charge more per kilowatt than during “off peak” periods.

Solar heating systems heat slowly – and not at all in cloudy, cool periods. Depending on the collector size and your location and climate, a solar system may not be able to warm the water to your desired temperature, even in the swimming season, except in the afternoon. And there is just not enough solar energy to heat your pool for swimming in the winter, early spring or late fall – no matter how many hours you pump.

What is the initial cost of a gas-fired heater?
Size for size, natural and propane gas-fired heaters cost the same. Prices depend on heater size, which in turn depends on the size of your pool – the gallons of water to be heated. A good rule of thumb is 6% – 10% of the total pool cost, if yours is an in-ground pool. And for this small added cost you get considerably more use from your pool. If you have also decided on a spa, the piping to the pool is negligible in cost.

If you think of buying a pool in the same way you think of buying a new car, consider a heater the same way as adding a radio or air conditioning to an automobile. It’s an extra convenience you don’t use all the time, but it adds immeasurably to your enjoyment. With a pool heater you can swim anytime you choose.

What about installation charges?
With natural gas-fired heaters, they consist of gas and water connections; for models with electronic control, an electrical connection to the filter pump circuit. Using propane gas requires a storage tank. With oil-fired heaters, you will require the services of a trained oil appliance technician and a storage tank. If your home already is heated by either oil or propane, the installation probably can be tied into your regular fuel supply.

In some areas, gas companies will make the gas installation with only a nominal charge. Check with your local gas utility.

All things considered, which method of pool heating is the least expensive?
Studies of 10-year “life cycle” costs have consistently shown that a good pool cover and a fuel-fired heater combination is less expensive, overall, than an active solar system alone, or active solar system and fuel-fired heater combination. This is true even state tax credits are allowed for installing the active solar heater. Unless you live in an area where your electricity is generated by water power (hydroelectric), it is also true that the life cycle cost of a pool cover/fuel-fired heater combination is much less than that of an electric heater or combination.

What size pool heater will we need?
Heaters are sized mainly on the basis of the pool surface area and the difference between the pool and air temperatures. The average air temperature for the coldest month of pool use is used in the calculation.

The heating load could also be affected by such things as excessive wind exposure or much cooler night temperatures than daytime air temperatures; in those cases a heater with more capacity may be desirable.

Another factor which may determine the size of the heater you will need is the way you intend to use your pool. There are two common pool heating practices – “constant” temperature maintenance and “intermittent” heating. These are determined by how you want your pool heated – continually or on an intermittent basis.

To heat a pool quickly after periods of intermittent shutdown, a larger gas-fired heater is needed. And in colder climates a larger than standard size heater also is recommended for “constant” heating. Maintaining pool temperature requires the same amount of fuel regardless of the heater size. For intermittent heating however, a larger heater actually saves fuel because it brings the pool to temperature more quickly.

If you have questions about heater sizing, consult your heater dealer.

How can we conserve energy and still fully enjoy our pool?
First, keep your thermostat at the lowest comfortable setting-and mark this setting on your thermostat dial. Second, if you swim only on weekends and are not using a cover, keep your heater on a standby setting of 70 degrees. With a cover on the pool when you’re not using it you can leave the thermostat at your normal setting. Third, if you’re vacationing for a couple of weeks or more or shutting down for the winter, turn the heater off completely, including any pilot light. Fourth, use every available means to prevent heat loss. Shelter your pool from prevailing winds, using hedges, other landscaping, cabanas or decorative fencing as windbreaks even though the pool is covered. Finally, use a pool cover whenever you are not using the pool.

Is a pool heater safe?
As safe as any major heating appliance in your home. Most heaters are equipped with automatic safety pilots or ignition safeguards, pressure regulators, water pressure relief valves and other safety features. Shut-off controls are automatic. Electric shock hazard is avoided by construction and installation of the heater in accordance with strict electrical standards and codes.

How automatic is a pool heater?
All you do is set it. For heating only at specific periods, a time clock or electronic timers may be used for automatic shutdown and turn-on.

What features should we look for in a pool heater?
You should be concerned with economy of operation, reliability and durability. Conservation of energy and fuel economy are extremely important – and an efficient pool heater can achieve, both.

By eliminating wasteful heating, a heater can quickly pay for itself. For example, Most pool heaters are equipped with a sensitive thermostatic pool temperature control. It maintains the pool at the exact temperature desired without wasteful, long on-and-off cycles of heating and cooling.

Rust, corrosion and scale are the elements that deteriorate pool heaters fast. That’s why we make our sturdy 1-piece heater jackets rigid and strong, with single-seam welding and a new longer lasting, weather resistant coating that resists corrosion and ends flaking of finish. Our heat exchanger produces a scouring-action water flow that virtually inhibits scaling.

We have a salt-water pool. Any special problems?
Yes. Salt water is highly corrosive, and a heater must be equipped with a special heat exchanger and other features to handle it. These heat exchangers are usually very expensive. Consult with your local pool professional to decide which heater is best for your pool if using salt.

Will my pool heater require much maintenance?Usually, one maintenance inspection a year is sufficient to keep your heater working efficiently. Maintenance is largely a preventive measure used to safeguard your heater’s working condition. The ruggedness, corrosion-free construction and long-lasting finish of most heaters combine with simplicity of engineering to keep maintenance minimal.

How long should a heater last?
Some heaters wear out in three or four years, but other brands can last a lot longer. A product life of 10 to 12 years is not uncommon. Heater failure is usually the result of some outside cause-not normal usage – provided it has been properly maintained.

Could we add a heater later, after our pool is built?
Yes. Although a pool heater can be added at any time, it should be included from the beginning, just as a heating system is installed during the construction of a home. This means greater convenience for you and less installation cost. When you include a heater in the beginning, it costs only 6% – 10% of your pool investment and usually gives you 100% more enjoyment from your pool. If the heater is not installed when the pool is built, provision should be made for a heater stub-out in the return water line, and space or a concrete pad should be provided for future installation.

All things considered, what is the most important reason for choosing a heated swimming pool?
For the sheer enjoyment of swimming in real comfort – any time you want. Any time of the day, any day of the year. Owners of heated pools would answer this question in far more glowing terms, but what having a heated pool amounts to is the satisfaction of getting more – much more – from your pool investment in terms of year-round family fun.

Tips to help you conserve energy and heat your pool economically.
Keep a thermometer in your pool. It will pinpoint accurately the temperature most comfortable for you.
Keep your thermostat at the lowest comfortable setting. Each degree more heat than needed could add more to your monthly fuel cost and use up more energy than necessary.
Mark the “comfort setting” on the thermostat dial. This will prevent accidental or careless over-heating and waste of energy.
Lower thermostat to 70 degrees when pool is to be unused for three or four days. For longer periods, shut the heater off. You will save money on fuel consumption and help conserve energy.
Protect your pool from wind. Wind above 3 to 5 miles per hour can lower the pool temperature substantially. A hedge, cabana or decorative fence can be an effective windbreak.
Use a solar cover when pool is not in use. This can reduce heat loss by as much as 50%. If you are vacationing for a couple of weeks or shutting down for winter, turn the heater off completely, including any pilot light.
Drain heater completely prior to freezing weather. Freezing water inside the heat exchanger can result in costly repairs.
Get a maintenance checkup annually. It’s your best ounce of prevention. The cost is minimal and the service will keep your heater working efficiently for many years.

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