Overhead heater prob

Discussion in 'HVAC Heating & Cooling' started by RJD, Oct 6, 2012.

  1. RJD

    RJD New Member

    Messages:
    6
    Location:
    NY
    Hi guys, hope someone has an answer for my prob. I have a Dayton 200,000 btu overhead heater (3e232d ), and burners will not re-light, after room reaches thermostat temp. Pilot light is good, pilot valve clicks, burners go on, and then fan goes on. Everything works great, until garage reaches set thermostat setting, then burners turn off, fan keeps blowing (normal), but temp keeps going down, fan still running, but burners never turn back on, even though heat exchanger is cold, and temp in garage is way below thermostat setting. Fan will only shut off automatically, if i turn down thermostat all the way. If i turn thermostat back up ( pilot light still lit ), fan will come back on, but still no burners? If i try hours later, it will work again, but only up to the point where thermostat kicks off burners, and ''no burners" cycle starts again. Seems like something, other than thermostat, is remaining too hot to tell burners to re-ignite? Any help?
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,226
    Location:
    Cave Creek, Arizona
    Not without being there to do my own tests to see if the burner is NOT being activated, or if it is activated but not operating. In other words, should the burner be on but it is not, or is something NOT telling it to start. Once that is determined, then the circuits have to be tested to see where the problem is, and that is not something we can do over the Internet.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,798
    Location:
    New England
    Does the thermostat have batteries in it? If it does, have you changed them?
  4. RJD

    RJD New Member

    Messages:
    6
    Location:
    NY
    Well hell HJ, come on up. What could it cost me, to fly you up from Ariz., too NY? of

    Well hell HJ, come on up. What could it cost me, to fly you up from Ariz., too NY? A couple of bucks?.....lol Seriously, if i had an electrical schematic, i could probably do it my self. The only schematic on it, is the thermostat wiring, nothing else, and i've tried searching the net, including Dayton ( via email ), and all i could get was a user manual from them :( Was hoping by posting my model #, someone could help me out with a schematic too. I know there's a limiter, or heat sensor inside the exchanger box, and on the top left hand corner, there's a switch,( not sure exactly what the function is, but it says "blocked vent shut-off switch", that has no continuity, until i push button, then it does). So i assume that's working? There is a black/white wire coming from that, to pilot gas valve, but there is also a RED wire coming out of box too, to the valve, but have know idea where that originates from. If you, or someone else, has any inside info, on how i could obtain an electrical schematic for this beast, it sure would be appreciated :)

    PS: I do have a new gas pilot valve on the way, but if that's not the prob, then i'll be back to square one, when i change out pilot valve, and it's starting to get "nippily" cold up here in the "Great White North".......lmao :) Thanks for your input HJ :)
  5. RJD

    RJD New Member

    Messages:
    6
    Location:
    NY
    No Jad, it's a 24 volt set up!
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,226
    Location:
    Cave Creek, Arizona
    1; you test the valve to see if you have 24 volts to it. If so and the burner is not operating, then the valve is bad.
    2. If it does not have 24 v. but should be operating, then you backtrack on the wiring until you DO have 24v.
    3. Whatever is the next device downstream will usually be the failed item.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,798
    Location:
    New England
    Electronic thermostats, while switching 24vac, often run on internal batteries so the display and other functions can work. By no means all, but some, and if the batteries (if present) can produce similar results/problems... If the thermostat is a totally mechanical one, then that can't be part of the problem (well, it could, but probably isn't).
  8. RJD

    RJD New Member

    Messages:
    6
    Location:
    NY
    1. I did/do have 24v to valve ( new 24v trans )
    2. That's a prob, black/white wires from blocked vent spill sw, switch tested good, but 1 red wire coming from somewhere, and can't see where it's coming from, without using chain fall to lower unit, and tear apart on floor. What other item would be inside? Is it possible to see/test/replace that item, without lowering unit to floor..........it's only ME, and it's a BEAST :)
  9. RJD

    RJD New Member

    Messages:
    6
    Location:
    NY
    This a simple thermostat, no bells/whistles, and positively, no batts. It does work initially, just not after it gets hot, shuts off, cools down, THEN burners won't kick back on, when garage temp decreases?
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,798
    Location:
    New England
    If it won't fire, short the two thermostat wires together and see if it starts. A DMM can fool you with a voltage indication sometimes. Probably something else, but easy to check.
  11. RJD

    RJD New Member

    Messages:
    6
    Location:
    NY
    Well guys, i'm pretty sure it's the valve now. The guy i bought it used from, had the unit OUTSIDE, and male terminals on valve were corroded beyond saving. Tried Muriatic acid on them initially, but they are too far gone, to the point one of the sets broke off. When i put a jumper on the female, to broke male tab, and re-tried heater, it worked great through it's normal cycle. So it's a good thing i sent for a new valve :) Will post back with results, when i replace valve. Thanks for all the input guys, your help was greatly appreciated :)
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