It's no surprise the fact that aquastats are a type of control that is used with the boiler. There is a lot of confusion as to what exactly an aquastat is and how to find an aquastat replacement in case one breaks down.
An aquastat performs the same thing as a thermostat. However, an aquastat detects and controls the temperature of the water, unlike a thermostat that controls air. For hydronic heating, we employ both of them – the aquastat for controlling the boiler's water temperature as well as the thermostat for controlling the temperature in the room.
There are two components of the word "aqua" along with "stat." The word "aqua" means water. Stat refers to switch. An aquastat is essentially an electrical switch that switches the boiler off and on to keep the water at the correct temperature. You can look for the best aquastat controller via outdoorboiler.com/collections/aquastats-controllers.
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An aquastat is made up of three components: a temperature sensor (also known as a bulb), a switch, and a capillary tube that connects the two. A temperature-sensitive material termed to fill is used to fill the bulb and capillary tube.
In the water, the bulb is inserted. As they fill up, the water heats the bulb, which expands via the tube and presses on the switch. When the pressure in the boiler varies, the switch opens or closes, turning the boiler off or on.