How does this safety device work?

Old 08-04-18, 11:34 AM
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How does this safety device work?

Hello all,

I have seen this @03:06.
It has a plastic tube that is claimed to shut down the water heater when the fan doesn't work correctly.

Question> I only see one power line connected to the fan. How does this tube work to turn off the water heater if the fan doesn't work correctly.

Thank you
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Old 08-04-18, 03:20 PM
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It's a pressure switch which senses the vacuum or pressure generated when the pump is running. If there isn't enough pressure or vacuum to trip the switch then the burner won't turn on.

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