Helpful Information:

By heating the pool or a spa just a few hours each day, can extend the swimming season several weeks into the spring and fall. In warmer climates, a heater can allow you to swim all year round. Here is a glossary of basic terms that are commonly used for gas fueled heaters.

Gas Heaters

A typical gas-fueled heater uses natural or propane gas as the heating fuel. The water enters through one port of the front water header, then through the nine heat exchanger, and then out of the other port. Most of the heaters, water goes through at least four of the tubes and picks 6 to 9 degree F on each pass before leaving the heater.

The exchanger tubes are made of copper due to its excellent heat conductivity, there by transferring the heat effectively to the water. The tubes have fins to absorb heat even more efficiently and are topped with sheet metal baffles to retain the heat. However, improper water chemistry can easily attack this soft metal and dissolve it into the water.

There is a flow control assembly on the front header. This spring-loaded valve is pressure sensitive, designed to mix cool incoming water with hot outgoing water to maintain the temperature. Temperature control is achieved by flow regulation rather than direct temperature regulation. This design keeps the outgoing water no more than 10 to 25 degree F above the temperature of the incoming water. This prevents condensation and other problems that greater temperature differentials would create. When water temperatures are over 115 degree F, minerals suspended in water deposit in the heat exchanger. The design of the unit is such that it allows 100 gpm with 1 1/2 inch plumbing or 125 gpm with 2 inch plumbing.

The other major component of the gas-fueled heater is the burner tray. This assembly can be disconnected from the cabinet for maintenance or inspection. Depending on the size of the heater, there will be 6 to 16 burners, the last one having a pilot mounted on it. Individual burners can be removed for replacement. The combination gas valve regulates the flow of gas to the burner tray and pilot and is itself regulated by the control circuit.

Gas-fueled heaters are divided into two categories based on the method of ignition. They are millivolt or standing pilot heaters and the other being electronic pilot heater.

Electric Heaters

Electric heaters are used where gas heaters are impractical and also when you are heating a spa. Because of the cost of operation, the slower recovery and heating time, and the high amps required with the corresponding heavy wiring and electrical supply, electric heaters are useful in small portable spas.

The components are similar to gas heaters except the heat is derived from an electric coil that is immersed in the water flowing through the unit. This is also true of the small in-line electric heaters used in small spas. Often these in-line units have no control circuits or they might have only a thermostat control because the other controls are built into the spa control panel itself.
Several sizes of electric heater are manufactured, rated by the kilowatts consumed and, therefore, the BTUs produced. Here is a comparison of the energy use and output of the most common models:

   5.5-kilowatt (5500-watt) heater = 18,750 Btu

  11.5-kilowatt (11,500-watt) heater = 37,500 Btu

Each of these generally consume about one-third more power to start up than to run at the designated wattage.

Solar Heaters

A solar heater transfers the heat of the sun to the water. A typical solar installation consists of solar panels from which the water should go before it passes through the heater. In this way, some amount of heat can be gained from the sun first, and then the gas heater adds additional heat if desired. Sensors detect the heat on the panel and open motorized valves to divert the water to the panels before it gets to the heater. If the panels are cold, water flow will bypass the solar panels and go directly to the heater.

Solar heating systems are controlled by time clocks and/or thermostats because, in summer, the panels might add too much warmth to the water and some means of regulation is needed. They also have simple on/off toggle switches to completely disable the system.

Most of the solar heaters work by cycling water through solar collectors and back to the pool. These are called open loop systems. They employ unglazed collectors, made from plastic or metal, to absorb heat from the sun and transfer it to the pool water. Other solar heaters employ glazed collectors, that contain antifreeze fluid. As the fluid is heated, it is sent to coils inside a heat exchanger, which then transfers the heat to the pool water. These are called the closed loop type of systems. A newer type of collector is made of Lexan with polycarbonate refractor.

The major manufacturers install and service the units that they sell, so it is best to your benefit to understand the design and have the warranty from the manufacturer.

Usually the solar heaters are mounted on the roof, facing south. But with the flexibility of the designs available today, the panels may not face directly south and can be mounted on fences, shade structures garage roofs and slopes.

Heat Pumps

It is the heat pump in which heat is transferred to that water by taking the warmth out of the air that is created by compressing a gas. Pool and spa water circulates through the unit the same way as the other heaters, but does not pump any more heat than any other design of pool and spa heater.

A compressor in the unit exerts pressure on a gas, usually Freon, and generates heat. The water is circulated through a heat exchanger that is warmed by contact with the hot gas. The gas cools from contact with the water and is recompressed and heated to start the cycle all over again. The Freon used in heat pumps is a nonflammable, non-corrosive gas, which makes it suited to this application. Freon does not contain the chlorine component of the Fluorocarbon that makes it environmentally hazardous.

Though expensive, heat pumps are energy efficient and last a long time. They are not effective spa heaters because they take a long time to heat the water in the spa. Because they rely in part on taking warmth from the air, the hotter the surrounding temperature, the better and quicker they work.

Unlike gas-fueled heaters, heat pumps are rated like air conditioners, expressed in tons. In this rating, a ton is the amount of energy required to keep one ton of ice at 32°F for 24 hours. As a rough rule of thumb, one ton equals 15,000 Btu.

Oil-Fueled Heaters

These are not very common, and are designed identically to gas-fueled units but they burn #2 diesel fuel instead of natural or propane gas.

Conner Construction Corp. · 19008 W. Catawba Ave · Cornelius, NC 28031
Phone: (704) 896-8118 · E-mail us at: familyfunstore@aol.com