Boiler fires during every call for heat

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Old 12-30-15, 02:30 AM
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Boiler fires during every call for heat

I have a single zone system and an L8124a aquastat
Whenever the t-stat calls for heat it will fire the boiler. It will do this even is the temp is near 180 and the boiler just ran. The settings are 160 and 180.
This has been like this for the year we've lived here. I think it should only run when the temp gets down to 160, any ideas?
 
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Old 12-30-15, 02:37 AM
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Welcome to the forums.

That aquastat is set to keep the boiler at a minimum temperature of 160
On a heat call.... the burner will run until the boiler temperature hits 180 and then shut off.
 
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Old 12-30-15, 03:02 AM
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So you think my aquastat is to blame? The circulator will not run with out the boiler running no matter what the boiler temp is.
 
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Old 12-30-15, 08:14 AM
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The aquastat could be bad or drifted slightly. Does the boiler temp go above 180 while it's running?
I assume you have a coil for hot water, turn the low down to 150 or even 140. The low should be set just high enough to give you adequate hot water when there is no call for heat. It also controls the circulator.
 
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Old 12-30-15, 08:45 AM
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It shuts down at 180 consistently. Yes I have a hot water coil. I will try turning the low temp down some
 
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Old 12-30-15, 02:37 PM
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the differential is probably set too high. ( The diff controls when the circ is alowed to run and at what temp...) This is for domestic coil purposes..

If its set to the max 25 then @ your 160 Lo setting the circ will not come on until 175F.. Thats probably your issue as well as the lo being too high...

Set the Lo temp to 140F and the differential to 10. This will allow the circ to be allowed to run at 140F..

If you have limited hot water at this setting try the low at 150F.. and differential still at 10..

Let us know the out come..

It works like this. very simple.. The differential at 10 is the neutral point that the circ will be allowed to run at what ever the low setting is set for. Once you change the differential off 10 the circ will stay off longer the higher up the scale you go..

The formula is like this..

Lo 140 Diff 10.. 10 minus 10 = 0.. 140 plus 0 is 140F.. Thats when the circ will be allowed to run for call for heat ..

Lo 140 diff 20. 20 minus 10 = 10.. 140 plus 10 = 150f.. That when the circ will be allowed to run for heat call.


So you see with your diff probably being set at say 25 and the LO being 160... Then'''''

Lo 160 Diff 25.. 25 minus 10 = 15.. 160 plus 15 = 175F is when the circ will come on....


Geez I hope this is not an oil burner cause your probably burning through gallons and gallons of fuel.. Even gas you'd be just wasting fuel..
 
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Old 12-31-15, 12:59 PM
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Awesome information. That was my issue and I know have a much better understanding of how it works......thank you for your time
 
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Old 12-31-15, 01:40 PM
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Great glad I could help..
 
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