NC - someone remind me please.

Harry Bloomfield · 2018-09-10T10:50:57+00:00

A thermostat for a PSU has failed, the replacement needs to be closed at room temperature and to open at 40C. Will that be an NC type or an NO type please? I think an NC, but I always get confused over these things. Rather unusually - The cooling fan runs, when the sat opens.

Sep 10, 2018 23 Replies

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tabbypurr 7 years ago

Bimetal wallstats are/were used for cooling as well as heating.
The other contact can be used to redirect electrickery to heating water if it's a room stat, or vice versa.

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Theo 7 years ago

Thanks. So in a traditional heating system, where the options were hot water or hot water+heating, you would always be running the boiler and using valves to put either heating water (when the house was cold) or hot water (when the house was warm enough) through it, until such time as the hot water came up to temperature and the boiler would turn off?

Theo

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dennis 7 years ago

The fan doesn't run as the OP said.

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tabbypurr 7 years ago

there's a bit more to it than that. There are several classic 'plans' for CH.

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