Boiler Circulating Heat When Hot Water Demanded


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Old 03-14-06, 11:12 AM
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Boiler Circulating Heat When Hot Water Demanded

I purchased a home in Vermont two years ago which has a Laars Endurance EBP 110 system installed, providing both heat and hot water. This system was installed new in 2000. Just this winter I noticed that whenever the unit is responding to a demand for hot water, heat is circulated through my baseboard radiators. This is even with the thermostat turned off.

The plumber provided by my gas company said the problem is due to the absense of an external bypass and wants to charge me $600 to install one. I am a novice when it comes to understanding heating systems, but my perusal of the manual for the unit indicates that such a bypass is not required. The manual can be found here. This unit has its own internal circulating pump (which runs whenever the unit is firing), as well as an internal bypass.

I assume that the unit must have some sort of valve which prevents hot water from going through the radiators when there is no demand for heat. Figure 28 on page 21 of the manual shows a "priority valve" which would seem to accomplish this purpose. Also the wiring diagram (Figure 32 on page 30) shows a "heating zone valve." Might this valve or whatever controls it be faulty and account for the symptoms I am seeing?

As this is the first year I've seen this problem, I can't believe that the issue is with the way the unit is plumbed, but is, instead, associated with a failure of some sort within the unit. Note that I have a service contract with the gas company which covers the boiler, but not the plumbing. I therefore have a financial interest in seeing the problem not attributed to faulty plumbing.

Thank you very much for any help you can provide.

-Mike Wyman
 
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Old 03-14-06, 11:25 AM
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I would guess you have a flow control valve that is stuck open. Can you take photos of your syetm and post the link where we could see them?
 
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Old 03-14-06, 11:54 AM
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Originally Posted by Who
I would guess you have a flow control valve that is stuck open. Can you take photos of your syetm and post the link where we could see them?
Certainly. I won't be back in Vermont until this Saturday and can do it then. What exactly should I photograph?

-Mike Wyman
 
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Old 03-14-06, 01:12 PM
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The piping near the boiler, so that the pros can see what type of check valves are there and how to best resolve this most likely "sticky" issue.
 
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Old 03-14-06, 03:18 PM
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it definately sounds like a stuck flow check valve from what i read.
 
 

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