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Property Types & Construction

Aquastat

Definition and meaning of Aquastat in real estate.

An aquastat is a temperature-limiting safety device used to regulate the water temperature inside a hydronic heating system boiler.

In more detail

In hydronic systems, heat is transferred using circulated hot water. Similar to a household thermostat that monitors room air, an aquastat monitors the water temperature inside the boiler itself. When the water cools below a set point, the aquastat signals the burner to ignite, and it shuts the burner off when the water reaches its maximum operating limit.

This device prevents boiler overheating, ensures system safety, and optimizes fuel efficiency. Home inspectors evaluate the aquastat to confirm it is functioning properly and keeping the boiler within standard operating limits.

Key facts

CategoryProperty Types & Construction
Primary functionRegulates boiler water temperature
Applies toHydronic, hot-water, and steam heating systems
Safety rolePrevents boiler overheating and high pressure
Example

When the hydronic heating system failed to produce hot water, the technician determined that a faulty aquastat was preventing the boiler burner from firing.

Frequently asked questions

Where is the aquastat located?

The aquastat is mounted directly on or inside the boiler casing, with a temperature sensor probe submerged in the boiler water.

What temperature should a home boiler aquastat be set to?

It is typically set between one hundred eighty and two hundred degrees Fahrenheit for space heating, though settings can vary based on system design.

Can a homeowner replace an aquastat?

Because it involves working with high voltage and pressurized boiler systems, replacement should be performed by a licensed HVAC technician.

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