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burnham wont fire.its - 2 degrees out

krayz Member Posts: 5
I have a burnham steam boiler model ansz2113 I changed the thermopile but it still wont fire unless I jump the thermostat leads at the gas valve. any ideas where else to look will be much appreciated


  • Mark N
    Mark N Member Posts: 1,115
    Wiring Diagram

    Do you have the owners manual with the wiring diagram? Could be thermostat, pressuretrol, LWCO, flame roll out switch, Blocked vent switch. You might need to get a pro to look at you problem.
  • krayz
    krayz Member Posts: 5
    burnham wont fire

    I can get it to run once I jump the thermostat connections at the gas valve and it operates properly. it just wont start when the thermostat call for heat I again have to jump it??
  • Mark N
    Mark N Member Posts: 1,115
    Did you check

    Did you check the things I listed? Anyone of this things will keep the boiler from firing. The things I listed are usually in a series circuit to fire the boiler. Get help if you don't know how to trouble shoot these things. Do you have a multimeter?
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576

    You can often short out the thermostat wires imitating a call for heat, and then with a jumper wire, bypass the safeties, (LWCO, pressuretrol, vent damper, etc.)one by one, until you find which one is not allowing the boiler to fire. This procedure is only for diagnostics, as the safeties are there for a purpose-to keep you and your family alive!--NBC
  • krayz
    krayz Member Posts: 5
    burnham wont fire

    first I am very mechanally inclined and use to work with plumbers so I do understand all the basic concepts.oh and ty for the replys. apparently the problem is intermittent as I was going to check some of the items listed I turned up the thermostat an the boiler fired. any ideas what could cause this?
  • krayz
    krayz Member Posts: 5
    burnham wont fire

    I did not have to jump out the safties all I need to do is jump out the thermostat and it fires?????
  • Mark N
    Mark N Member Posts: 1,115

    Maybe the thermostat is no good.
  • krayz
    krayz Member Posts: 5
    burnham wont fire

    how do I check a millivolt thermostat?
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    You probably already did.

    If the thermostat should be calling for heat, according to what its temperature and set-point say, and jumping it causes the burner to fire, then that would be the test. You've basically proven that a thermostat that was doing its job would have turned on the burner already. You might want to try turning the thermostat up all the way to make sure it isn't just mis-calibrated, but there it is.

    This is assuming, of course, that you are connecting a jumper directly at the thermostat itself, not at the thermostat terminals on the gas valve. Because all your safeties and limits are in series with the thermostat, jumping the terminals at the valve only tells you that something in that circuit is open.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • Mark N
    Mark N Member Posts: 1,115
    Millivolt system

    I have never had a milliviolt system. I googled millivolt system and I got a hit for a document from Robertshaw on how to test a milllivolt system. A thermostat is just a switch that works on temperature. Make sure you get thermostat that is compatible with your millivolt system.
  • rich11coop
    rich11coop Member Posts: 25

    Are there batteries in the stat & are they good?
  • rrg
    rrg Member Posts: 37
    edited January 2014
    I had the same kind of problem with my Millivolt

    I have a millivolt system.

    I had the same kind of issue once and it turned out the small wire nuts at the boiler that connect the thermostat wire from upstairs and gas valve at the boiler were not crimped together 100%.

    Over time or with extreme temp changes the two wires, even tho they were twisted and wire capped they would not touch.

    It looked like the wires had some wire corrosion and the copper was not shiny.

    Strip some wire back and re-twist and cap the wires.

    Worked for me.

    My thought is that moving the wires around with the thermopile you might have loosed some of the wire connections (ie wire caps). I am assuming you had everything working before you changed the thermopile.
  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    I suspect that rrg

    has it pretty well doped out.  A thermostat -- even a millivolt one -- is, fundamentally, a switch.  Either it is open or it is closed.  Or so it seems.

    Problem is that in millivolt systems you are dealing with very small voltages -- and even smaller currents.  Even one bad connection somewhere can make it so that the circuit behaves as an open circuit.  When you jumper the thermostat terminals, you are taking the whole thermostat circuit out of the picture, and substituting a very short -- very low resistance -- one.

    So... check all your connections.  Bright wire.  Tight connections.  Check the contacts on the thermostat itself (if it's a mechanical contact).  Clean and bright.  If it's electronic, batteries.  The only thermostats which are bulletproof that way are the old mercury Honeywells -- provided the anticipator is cut out of the circuit completely.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England