Boiler Vent Damper
Hi all- I have a 2012 Burnham Series 2 boiler in my house. A week ago it stopped putting out heat. Error 56, vent damper. Figured out how to put it in manual override and turn that rod to the open position. Boom, immediate heat. Got a tech on the line to come see it. Of course he's too slammed so I swapped out just the Field Controls motor. All was good for a day, then switched off again. Same error 56. Rinse and repeat on the manual mode. Talked with another tech about it. He said to just leave it in manual mode. He explained its just an efficiency thing that I wouldn't notice. Anyway, here we are now again no heat. (48hrs later and no heat same error 56.) Eegads! What gives with this thing? Home has become my new jail because I can't leave the house now…. Any ideas?
Comments
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There is a reason I dislike flue dampers… they do contribute a tiny bit to efficiency, but they are a total pain — usually the least reliable part of a system.
Turn the thing to manual, open it, and let it be. And be happy.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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@Jamie Hall -That's the problem. It is in manual mode. The vent will be in the open position. But something is still telling the boiler that its the vent's fault and shutting it down. Wiring? Computer board? Another sensor?
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Ah. I misunderstood. First thing to check is all the connections — there are several plugs on that wiring harness. Unplug them all and check that the wires are well seated in the pins and that the pins aren't bent or the sockets distorted. No corrosion on the pins or sockets. Plug them all back in and make sure they are firmly seated. Check that no mice have lunched on the wiring…
If you have a manual, it should tell you which pins on the connector at the damper are the sense switch — you can try jumping them to see if it is the switch in the damper (if you don't have the manual, tell us the model number and @EdTheHeaterMan will likely be able to tell you what to jump).
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
Error 56 indicates that the damper did not close. And that makes sense since you have it locked open. This is a tricky one to resolve. So this makes me believe that the damper must open the proving contacts in order for the boiler control to go into the startup sequence. That would mean that there must be no voltage at pin # 5 on the P6 plug (where the damper plugs in) on the boiler control. With the damper manually open there may not be a way for the switch in the damper to open.
How to determine if it is the damper or the cable or the boiler control is what we are going to figure out.
You will need a multimeter with a set of needle leads that can push into the back of Molex Plugs while they are still plugged in. The standard leads are too thick and may damage the plugs.
Do you have such leads? We can go thru the test procedure as long as you have the proper tools. Please let me know if you have the needed meter and leads.
Lower the thermostat below the room temperature and unlock damper from manual open. The damper should be closed and Voltage should not be present on Plug P6 pin 5. now turn up the thermostat and initiate a call for heat. The damper should open. Once the call for heat is satisfied the damper should close after a suitable delay to vent combustion gasses. if you get the ERR 56 code at any time during the cycle then the Control, the vent damper, or the wire harness is defective. While the Err 56 is displayed by the control, perform the following tasks:
- Remove call for heat (adjust thermostat or remove wire from thermostat connection.
- Check for 24 VAC between P6-5 and ground.
- If voltage not present, attempt to start boiler again.
- If 24 VAC is present, unplug vent damper harness from control.
- With wire harness unplugged, check for 24 VAC between P6-5 (on Control) and ground.
- If voltage present, replace control.
- If voltage not present, it is a failed vent damper or wiring harness.
- Check wiring harness for shorts or mis-wiring. Replace if defective.
- If harness not defective, replace vent damper or damper motor .
I hope this helps.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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They also reduce cold air infiltration when closed, by blocking the flue. So the entire building's efficiency goes up.
My bet is the control.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting
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They get you coming and going. Now you can't even bypass a draft damper? That's ridiculous considering it's not a safety.
Why is the Auto/Man switch still there if its useless? Are U.S. Boiler and Fields Controls not on the same page?
In what scenario is an open flue passage a danger? I don't see anything in the manual showing a bypass. Maybe it's a secret Burnham Tech Support has. That would irk me so bad I'd rip the control and go old school Series 2 with the Fan Center Control. Because sometimes technology sucks.
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@HVACNUT -
"Why is the Auto/Man switch still there if its useless? Are U.S. Boiler and Fields Controls not on the same page?" —Was thinking the same thing. I feel hoodwinked into buying another motor. Thankfully the supply warehouse guys were kind to me and only charged me $185.
@EdTheHeaterMan and @Jamie Hall - Thanks guys! So appreciate you leading me somewhere on this. I'll let you all know where I end up.
*****UPDATE****
Spent a good part of the day studying sequence of events. Turns out that something is happening when the call for heat turns off, such as lowering the temp on the thermostat, that is causing the system to sporadically not shut the vent damper. Seems to be worse the colder the system has gotten, for instance if the circulator can just get away with moving extra hot water around the zones then something isn't telling that vent damper to close. Then the next time it calls for fire the stupid thing thinks its already closed, gets confused and won't fire up. (Unless you manually turn the damper rod then the motor takes over and makes a full circle and it fires.) Anyway, tested P6-5 while it was in err 56 mode. I had volts…points to control board instead of the harness. …watch it work perfectly now…
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Is the control board warranty?
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-No. System was installed in 2012 by the prior owners. SupplyHouse is sending one for $278 to be delivered tomorrow. I'd rather a pro be doing this, but the skyrocketing house prices in W. MT has prohibited people that actually have a trade and actually work from being able to live here. The shop I usually use couldn't set an appointment for two weeks. All the other shops I called stopped doing service calls. So here I am, being an amateur. Anyway, appreciate your willingness to help me out here.
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Hello etak_eiram,
With a multimeter is should be fairly easy to follow the sequence 'Back Probing' the connector pins to see where the power stops or becomes erratic. All measurements referenced to a good ground.
Circuit Point 1 and 2 = P4-1, P5-6, P6-1, Damper pin 1 should be 24 VAC all the time.
Circuit Point 3 = P5-4, also should be 24 VAC all the time.
Circuit Point 4 = P6-5, with the thermostat closed calling for heat it should 24 VAC after contact 'A' closes activating the Damper.
Circuit Point 5 = P6-2, 24 VAC when the Damper opens and the Damper End Switch closes (contact 'B') .
Circuit Point 6 = P5-2, 24 VAC when contact 'C' closes.
Circuit Point 7 = P5-5, 24 VAC when contact 'D' closes.
https://www.powerequipmentdirect.com/manuals/1a167f901be305475721dde5321de827.pdf?srsltid=AfmBOooClfJwmjDQMNz83P-nrH2UHBOxuI-iCxuTh4x5ilQYvMhQmBhn
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
Update #2- New board installed on a Thursday afternoon, it is now Tuesday morning and all is operating without issues.
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