Heat exchangers are normally used in conjunction with a gas or oil boiler.
The boiler supplies high temperature hot water to the copper pipe connections on the heat exchanger.
As the pool water runs through the heat exhanger, it is heated indirectly from the boiler water.
A thermostat is used to control when to call for heat from the boiler
Our sizing guide for heat exchangers is 10 BTU per gallon of pool water (or 2.9kw per 4.5m3 of pool water)