Often people are confused as to what is an indirect water heater and what is a normal domestic water heater, so let me clear this one up.

An indirect water heater is one that uses a dissconnected source to heat the water. This heating source is usually the boiler that you use for the space heating for your home.

The Indirect Water Heater is where water is piped from a high efficiency boiler into a heating coil inside the insulated tank that holds your potable water and transfers its heat to the water. These systems are very efficient as the boiler is heating a large volume of potable water which is stored in a well insulated tank. Many systems quote efficiencies well above 90%, so if you are in a cooler climate, indirect water heaters can bring your hot water costs down significantly.

These are very efficient and about the most cost effestive way of obtaining hot water, provided your homeuses a space heating boiler. Obviouly you need to size your tank to suit your family requirements.

Indirect Water Heater

The type of tank lining should be considered carefully as different areas have different water qualities. New England for example has acidic water and linings such as Hydrastone work well to protect the tank. Other manufacturers use stainless steel, Vitraglas or enamel, best thing is check out the guarantees.

Indirect water heating can also apply to cool climate solar powered water heaters. This is where an alternative liquid like glycol instead of water is run through the solar panels so they don’t freeze at night. This then circulates through a heat exchanger in the water tank to heat your potable water.

1: Municipal water feed
2: Fluid from water storage tank to external (passive) heat source; passive heat source can be the ground (soil or groundwater), sun or air; eg via heat pump, or thermodynamic solar panel
3: Fluid from heat pump, or thermodynamic solar panel to water storage tank
4: Pump, actuator, controller and other parts
5: Water heater
6: Water storage tank
7: Hot water to domestic appliances

Hopefully this answers the questions of “what is an indirect water heater?”

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