vented HW tank silly question

[DMac]

Just replaced old hw tank - where is optimum place to fit the tank thermostat?

Many thanks

[Set Square]

Fairly low down - maybe 1/4 of the way up. Bear in mind that there will be a vertical temperature gradient in the cylinder, with the hottest water at the top. If the stat is too high, it will turn off the heat source before most of the water is hot.

[Christian McArdle]

The closer to the bottom, the greater the effective capacity of the cylinder. But ensure it is a little higher than the bottom of the coil, or it will never be satisfied.

Christian.