Where to place an aquastat that is external to the hot water tank?

Question

If you need to retrofit an aquastat to a heating system what is the best way to do so?

i.e., in some hot water tanks or even boilers there may be a purpose-made port specifically to accept a "well" into which an aquastat temperature probe / sensor can be placed. But if that port does not exist, or if it has been used for something else, what's a good alternative method of attaching the aquastat?

StayOnTarget · Answer

A more accurate temperature reading will come from the use of an immersion thermostat / probe, rather than the type which can be strapped onto the exterior of a pipe. Such an immersion device is placed into a "dry well" which itself is immersed in the water.

The positioning of the well relative to the heat source, and its orientation relative to water flow are very important to ensuring an accurate reading.

Positioning the thermostat:

Orientating the well:

Optimal:

Incorrect:

Example assembly of the well into the pipe fitting:

Example insertion of the actual probe into the installed dry well:

Example of completed plumbing install:

A lot of this information came from  Heating Innovations Limited (UK).

Where to place an aquastat that is external to the hot water tank?

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