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casaram

Heating circulator not coming on

casaram
10 years ago

I have a 3 zone oil furnace/forced water heating system, and the circulator for one of the zones is not coming on. Other zones are both working fine.

The circulators are all Taco, and the relay for the circulator in question is a Triple Aquastat L8151A which appears to also control domestic hot water.

As far as I can tell so far domestic hot water is working, but I've only run it for a few seconds so I don't waste what may be only reserves left in the tank.

If I turn my thermostat up I can hear and see the relay inside the aquastat engaging, and if I turn it down I can hear and see the relay shutting off.

One relevant piece of information is that I first noticed this happening after taking off my old mercury thermostat and replacing it with a Honeywell RTH6350. That said it could have been a problem for some time and just not noticed as the heat hasn't been on to any large degree yet this season.

To rule out having messed something up by my new thermostat install I put the mercury thermostat back as it was and things are now in a state where I can hear the relay come on when I turn the thermostat up, but no circulator.

Any help or ideas would be appreciated.

Thanks!

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