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W-M VHE intermittent lockout

vwyvwy Posts: 6Member
I have a 22-25 year old VHE that works fine except about 2 months ago it started locking out around once a day or so. My plumber has tested the system and changed out the ignitor, sensor, gas valve pressure switch relay and two controllers from a honeywell to the white rogers and back to honeywell again. The only part not changed is the blower but that seems to be working fine and the pressure tests out good. All test out fine (but since it is an intermittent problem that may happen). Now he says that the only thing he can think of is replacing the furnace. Could it possibly be a transformer? Also, I did observe one time when it locked out that the system fired up and the flame blew out immediately and the system locked out. It will restart if I cycle the power or pinch the pressure switch tube momentarily. Does anyone have any thoughts for something I can check or look harder at. I believe the furnace is still fine- at least when it fires up. Thanks

Comments

  • SWEISWEI Posts: 7,356Member
    vwy said:

    My plumber has tested the system and changed out the ignitor, sensor, gas valve pressure switch relay and two controllers from a honeywell to the white rogers and back to honeywell again. The only part not changed is the blower

    Consider replacing your plumber with a trained and qualified boiler technician. Hope you haven't paid for all this non-work. Where are you located?
  • Steve MinnichSteve Minnich Posts: 2,468Member
    It may be (probably is) something as simple as a poor ground or reversed polarity.
    PHC News Columnist
    Minnich Hydronic System Design & Consultants
  • Tim McElwainTim McElwain Posts: 4,281Member
    Give a list of controls you have on the boiler, this will help me give you a direction to start proper troubleshooting. Make and Model of the controls is important and pictures also help.
  • lchmblchmb Posts: 2,946Member
    LP or natural gas?
  • Empire_2Empire_2 Posts: 2,343Member
    SWEI,............................. Laughing and still on the floor rolling around a bit. My sentiment exactly. I was thinking on replacing the house.....lol

    Peace;
    Mike T.
  • Steve MinnichSteve Minnich Posts: 2,468Member
    Still betting on a poor ground.
    PHC News Columnist
    Minnich Hydronic System Design & Consultants
  • vwyvwy Posts: 6Member
    Gentlemen

    Thank you for the responses. I have been away and it is getting problematic again. My thought was a bad ground somewhere. WOuld it hurt to add a separate ground from the current ground (controller to chassis) from that leg to another spot in the chassis? To answer a few of the responses... I am in Southern NH, this is LP and it is a honeywell model S8910U controller. Anything else?

    Thanks again
  • vwyvwy Posts: 6Member
    Oh I forgot, I observed it going into lockout this morning. The ignitor came on, gas valve opened and the flame started and "blew itself out" or at least that is what it looked like
  • Tim McElwainTim McElwain Posts: 4,281Member
    You need to check microamps when the flame is on. It will not hurt to run an additional ground from burner ground on the S8910 to gas valve with an 18 gauge wire.
  • vwyvwy Posts: 6Member
    Tim Thanks for the information. Now not to sound too much like a brick, across where am I measuring the micro amps? I know how to measure, but I'm not sure what I am measuring(quantity) or where with the flame on. It would seem that this measurement is easy, since it is done in the "functional" state, not when it is locking out.
    I will also set up the additional ground on the off chance it works
    Thanks
  • Tim McElwainTim McElwain Posts: 4,281Member
    Place the microamp meter between burner ground terminal on the S8910 control and the wire removed from burner ground. You should get somewhere between 2 to 10 normal around 3 to 5 microamps.
  • vwyvwy Posts: 6Member
    Tim

    Thanks for the information. The ground checked out fine but I added another as well. It didn't fix the problem so I had another heating guy look at all the connections etc. Unfortunately it didn't lock out for about the 3 hours he was there. Just before he left two of the burners lit with a flame "roll back" I then had him restart and it failed. A check showed that there was no voltage from the controller to the gas valve to open it. At that point I was told it was the relay in the controller and it was changed again. The one in there has been put in about a month ago.Either the controller was bad from manufacture or there is an upstream cause that hasn't been found yet.

    It is possible the Honeywell controller was "bad" but I have no experience with this. I would appreciate any thoughts as to whether this sounds too simple a fix or if I should be checking something else.

    Thank you all for your comments. All have been most helpful
    VWY
  • Tim McElwainTim McElwain Posts: 4,281Member
    The S8910U Universal Replacement Modules have been very reliable. It is possible that you got a bad one.
  • vwyvwy Posts: 6Member
    Tim Thanks that was what I have been seeing. My concern is that there is something causing this internal relay to fail. Perhaps I am a bit skittish at this point and looking for ghosts.

    Thanks for all the help
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