What is an Aquastat?



For many people the term “Aquastat” isn’t one they’re familiar with, in fact you may be wondering if this is even English. An Aquastat is quite simply a thermostat for water.  It’s typically used to keep boiler water within a specific temperature range. Your next thought might be, who cares? While boilers aren’t extremely common in American homes yet – they’re growing in popularity every year.

In areas of extreme temperature changes, basically the whole top half of the country, home builders are expecting to increase their use of radiant floor heating by as much as 40% in the next year. The reason for this is that a radiant floor heating system provides more consistent heat throughout the home with cleaner air quality and lower cost of operations.  As this information becomes more common knowledge, more and more new homeowners are requesting radiant heat.

Within the radiant heating system is a boiler and, often an aquastat, which can be incredibly helpful to maintain safe and effective water temperatures. The aquastat contains three components: a switch, a temperature-sensing bulb and a capillary tube that connects the bulb to the switch. Within the capillary tube and bulb is a liquid called “fill” which is temperature sensitive.  When the bulb heats up the fill expands which puts pressure on the switch and causes it to either open or close.  If the switch is open it breaks the power circuit between the boiler and the heating mechanism which turns the heat off and causes the water to cool.  After the bulb temperature drops enough, the fill condenses, the switch closes and the boiler begins to run again.

If your home contains radiant heat and you begin to notice a problem with the system it’s possible that the aquastat, or the boiler, has failed in some way.  All Star Plumbing and Restoration’s licensed plumbers are qualified to assist homeowners with issues relating the boilers and, by proxy, the aquastat. If you don’t currently have radiant heating it may be something you should consider the next time your furnace dies and you’re in need of a new heating system.  While the initial cost to change over may be higher, the long term benefits are substantial.

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