Burnham Revolution boiler circulator pump not working


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Old 01-25-23, 11:30 AM
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Burnham Revolution boiler circulator pump not working

Hi all,
I found this site after the following thread came up in my search:
how to troubleshoot internal variable speed pump in Burnham Revolution - DoItYourself.com Community Forums
My baseboard radiators were not heating properly topping out around 110F. The boiler itself was starting and cycling on and off at the proper set temps. I zeroed in on the circulator pump which I discovered was not operating and mixing with the heating loop. I followed the advice on the above thread and come to the conclusion that my thermistor was loose, but operational. It had a broken clamp but it was still touching the output tube. It also measured ~970 ohms at ~190 degrees.
I disconnected the thermistor, and that did not kick on the circulator as it did for the OP. That left jumping the pump wires 1 and 3 on the VS3000 mixing board, which did the trick. The circulator lit right up and my radiators came right up to temp.
So here I am with a system that is operating normally but the circulator is jumped to full speed. I don;t see how that can present an unsafe condition, but what other troubleshooting can I do before I replace the VS3000?
Thanks in advance.
 
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Old 01-25-23, 04:19 PM
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Does not sound like a bad VS3000 from your description.
Was the clamp broken and just a small bit of the sensor was touching the pipe?
That sensor should be mounted and clamped tight on the top of the supply pipe pushed all the way back where the end of the sensor is touching the cast iron block.
When operating normally the upper power light should be on steady anytime the boiler is in a demand. The %on light may flash until the boiler water temperature gets to about 160f where the %on light would become steady.
To troubleshoot board give the boiler a demand. Measure voltage between 1 & 2 on the vs3000. You should have 120v. Terminals 2 & 3 could be anything and will be bouncing all over the place. When the temperature gets to about 160f the reading should be 120v.
If the Power light is flashing on a demand, it means the sensor is bad otherwise should not ever flash..
 
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Old 01-25-23, 05:22 PM
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rbeck Good stuff. I will check the voltages in a minute. The clamp was crumbled but the sensor was still lying flat against the top of the pipe. I secured it with a nylon zip tie. I didn't have concerns about that part, as the readings on the pressure/temp gauge and infrared thermometer matched the set temp on the aquastat. The resistance I got was on the money according to the manual (977ohms@190F).
The power led is steady on when the system has a call for heat. I have never seen the % light flash. It has always been steady. Even with disconnecting the thermistor, the % lights stays solid. I thought a disconnected thermistor would cause a "low temp" condition therefore slowing the pump and flashing the % light?

 
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Old 01-25-23, 06:51 PM
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OK while the boiler is firing, I am getting 120V across terminals 1 and 2, but only 0.9V across 2 and 3, regardless of temp. Also, when the temperature is the system was around 145 degrees, the % light was steady. I understand that is supposed to be flashing at that temp.
Seems like that part of the circuit is defective.
 
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Old 01-26-23, 01:27 PM
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I agree. The voltage output 120v voltage should be bouncing all over the place.
What type of radiation do you have in the home? How many zones?
 
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Old 01-26-23, 09:11 PM
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The system has three hot water baseboard heat zones (one on each floor) and an indirect hot water zone 4.
So you are thinking it is probably the VS3000 after all?
 
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Old 01-27-23, 09:51 AM
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Yes but I am trying to figure out if it needs changed or bypassed.
That boiler was introduced in 1996 and could operate well with the lowest return water temperature in the industry, 55f. Unheard of then and not sure anyone has matched it to date on a cast iron boiler. It was designed for large water volume systems or radiant floor systems. In theory it was not to be designed for low water volume high temperature systems.
If your zones are copper tube baseboard just leave it bypassed, it will be fine.
 
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Old 01-27-23, 03:09 PM
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Thank you very much. So, to be clear, there is absolutely no way this bypass of the variable circulator speed presents an unsafe condition? If so, I will be happy to leave it as is.
The only negative I can see is a slight delay of getting the entire system up to temp from a dead low (as if we went away on vacation and shut the furnace off in the winter, which we would never do).
Thank you for your advice.
 
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Old 01-28-23, 03:38 PM
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Totally safe. The only benefit was to stop the boiler from condensing in an extended cold return water condition.

 
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