Laars Endurance EBP Does Not Activate Circulator Pump


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Old 01-11-17, 12:34 AM
J
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Laars Endurance EBP Does Not Activate Circulator Pump

I have a Laars Endurance EBP propane heat/hot water combination boiler. Suddenly our heat stopped working. I discovered that the circulator pump was not pumping hot water through the system. The pump itself is fine.

It is an external circulator, not the built in Laars pump. It seems to be controlled by a Honeywell motorized zone valve... when the zone valve opens, there is an electronic switch that closes to send power to the circulator.

The thermostat seems to be closing the normally open connection to the boiler to call for heat but the Laars is not telling the circulator and zone valve to go to work. I checked and reseated a lot of connections under the control panel and everything seems fine.

The interesting thing is if you turn off the boiler and power it back on... it will open the motorized zone valve and excercise the circulator for about 20 seconds so I know the boiler has the ability to tell it to run but it is not for some reason. I appreciate any help! Thank You
 
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Old 01-13-17, 05:53 PM
J
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It turned out to be the water flow sensor for the domestic hot water. It is a black plastic sensor that screws onto a brass fitting on the cold water inlet. It senses when you are calling for hot water for a shower, etc. and temporarily locks the heat out because it gives priority to hot water. There was a piece of debris caught on the sensor paddle, keeping it stuck down and making the boiler think we were using hot water thus preventing the heat circulator pump from turning on. -Jeff
 
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Old 01-13-17, 07:23 PM
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I was just getting ready to respond to you. I'm glad you found the problem.
I had been reading the service manual for that boiler for the last hour. Not too much helpful info. Very expensive control panel in there +/-$650.

I had suspected the ACV (anti condensing valve) as a possible problem.
 
 

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