Boiler will only start from one zone.


  #1  
Old 03-08-20, 03:45 PM
J
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Boiler will only start from one zone.

Hi all, I have a Weil Mc Lain forced hot water oil fired boiler. Two zones. One zone working fine. Lowered the tstat for that zone so not to kick on. Turned the tstat up on zone two. Boiler will not fire up. two separate circulators. Purged both zones. New tstat. Not sure if there's a way to by-pass the tstat or if that would even help.I have searched all I can with no luck find this exact issue. Has to be something simple I'm missing or atleast I hope.
 
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Old 03-08-20, 04:05 PM
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Does the circulator for zone 2 run? If not, check the switching relay to verify you are getting power to the circulator.
You can also check to see if you are getting 24 volts to the thermostat.
 
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Old 03-08-20, 07:25 PM
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I figured it out. I took the cover off the aquastat and pulled the relay thing and it fired right up. Thank you for the reply Grady.
 
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Old 03-09-20, 07:35 AM
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sometimes relays get stuck. I would keep and eye on it going forward just to make sure it isn't on its way out..

Alternatively, sometimes techs wire up second zones incorrectly. When I bought my house, i found one zone worked properly (it was wired directly to the aquastat). The other three zones were wired offer of two different honeywell relays to run their circs but they were not wired to fire the boiler at all (so it would only deliver water based on the boiler lo temp setting). The techs solution was turn the lo temp up to 175; pretty big waste.

Glad its working for you now.
 
 

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