Pool Heat Exchangers – What Are They And How Do They Work?
If you have been reading and researching about ways to heat your pool you most likely will have come across the term “heat exchanger”. A swimming pool heat exchanger uses hot water from a boiler or solar heated water circuit to heat the pool water. Heat is transferred by conduction through the exchanger materials which separate the mediums being used.
Heat exchangers allow heat from a fluid (a liquid or a gas) to pass to a second fluid (another liquid or gas) without the two fluids having to mix together or come into direct contact. The essential principle of a heat exchanger is that it transfers the heat without transferring the fluid that carries the heat.
All heat exchangers do the same job—passing heat from one fluid to another—but they work in many different ways. The two most common kinds of heat exchanger are the shell-and-tube and plate/fin.
Shell and Tube Heat Exchangers consist of a large number of small tubes which are located within a cylindrical shell. The tubes are positioned into the cylinder using a tube bundle or “tube stack” which can either have fixed tube plates (permanently fixed to the body) or, a floating tube stack which allows the tube bundle to expand and contract with varying heat conditions as well as allowing the tube bundle to be easily removed for servicing and maintenance.
Plate Heat Exchangers operate in very much the same way as a shell and tube heat exchanger, using a series of stacked plates rather than tubes. Plate heat exchangers are usually brazed or gasket depending on the application and fluids being used. Their compact stainless steel construction makes them an ideal choice for use with refrigerants or in food and beverage processing.
Heat exchangers can be used in many pool and water applications: Salt water and chlorinated swimming pools, Jacuzzi’s, Whirlpools, Spas and Hot Tubs, Solar heated pools, Domestic Hot Water Supply, Sea Water applications, Hot Climate applications and Waste Water Heat Recovery. This means that no matter why you’re looking at heat exchanger options there will be a heat exchanger suitable for your pool.
When looking at pool heat exchangers be sure to look for brands that offer you the following:
Corrosion is a problem in both chlorinated and salt water pools. If your heat exchanger has been constructed with corrosion resistant materials, you will find that they last pretty much forever!
No one likes extra maintenance. Check the heat exchanger allows for a high flow rate through it. If the flow rate is high, then you will find your heat exchanger requires very little maintenance and will be inherently, self cleaning.
Long Life Span
If your heat exchanger has wide channels then it will take a lot longer to build up any hard water scales and therefore your heat exchanger will have a longer life span.
On top of looking at these benefits, you should also consider their efficiencies. Not all heat exchangers are built the same.
Heat exchanger efficiency can be defined in many ways, and in terms of thermal performance there are several key factors to consider;
Temperature differential – The difference between the hot fluid and coolant is very important in a heat exchanger. The coolant always needs to be at a lower temperature than the hot fluid. Lower coolant temperatures will take more heat out of the hot fluid than warmer coolant temperatures.
Flow rate – A greater flow rate will increase the capability of the exchanger to transfer the heat, but a greater flow rate also means greater mass, which can make it more difficult for the energy to be removed as well as increasing velocity and pressure loss.
Installation – The heat exchanger should always be installed based on a manufacturers’ guidelines. The most efficient way to install a heat exchanger is with the fluids flowing in a counter-current arrangement (so if the coolant is traveling left to right, the hot fluid travels right to left) and for shell and tube heat exchangers the coolant should enter at the lowest inlet position to ensure that the heat exchanger is always full of water. For air cooled heat exchangers it is important to consider the air flow when installing a cooler, any part of the core which is blocked will compromise cooling capacity.
Investing in a pool is not a small task. Getting the right components so you can enjoy your investment needs experience and knowledge. Talk to us at Pool Heating Ltd and we can advise which options will give you the maximum efficiency and best result for your pool for years to come.