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Weil Mclain Ultra won't fire

JimHJimH Member Posts: 89
oh yeah, and just like the other guy said; remember: gas goes boom!!!!


  • rnrn Member Posts: 13
    Weil Mclain Ultra won't fire

    I received some great advice on this forum about a year ago to tune an Ultra 155. Now I'm back again.

    My Ultra 155 stopped in the middle of the night. It has been operating flawlessly for about a year now. The error code it is getting is E 02, which is failure to fire after 5 tries. I can see spark, and it is getting gas (smell and I can see the gas meter move when it tries to ignite). I spent some time on the phone with a Weil Mclain support tech. He diagnosed it as a control module. I've replaced the control module, but have the same problem. Now it is Saturday and I can't get support from Weil Mclain until Monday.

    I am also having trouble finding a good contractor to work on this. There just isn't that many people that are good with Weil Mclains I guess. It doesn't help that the local Weil Mclain rep is out of the office until Tuesday.

    I'm confused by it stopping after working all winter. I've checked the air lines, gas lines, and power. If there is interest I can post the testing I ran with the Weil Mclain rep.

    Has anyone seen anything like this before?

  • Al LetellierAl Letellier Member Posts: 929

    Had a strange one on an Ultra the other day as well. Can you see the ignitor lighting up? Mine wouldn't ignite after seing the ignitor and the gas valve powering open. I had to "burp" the gas line to get it going. I disconnected the gas line at the union and opened the ball valve. Got a Pop and then smelled gas. Put it back together and voila...ignition and no problem since. DO NOT TRY THIS YOURSELF. GET A PRO. IT CAN BE VERY DANGEROUS IF YOU DON'T KNOW WHAT YOU ARE DOING....GAS GOES BOOM VERY EASILY IF YOU ARE NOT TRAINED.
    I don't recommend you do this yourself. It's just my example of what can go wrong, sometimes with no reasonable explanation. Anybody trained in gas service should be able to help you with this. There isn't that much different with the Ultra as far as components.
  • rnrn Member Posts: 13

    I have checked for gas flow. I am wondering if it the ignitor. I checked it's voltage on the low voltage panel and it was < 2V. The specs are 4V and higher. The other concerning thing is that I am not getting 24V across the thermostat terminals......
  • JohnJohn Member Posts: 63

    get a manometer and check the gas pressure, smelling gas isn't a barometer of gas pressure... you need to know how many inches you have in W.C.
  • Al LetellierAl Letellier Member Posts: 929

    Sorry I left that out. Certainly on of the first steps in troubleshooting and mine was right on. Still don't understand why "burping" the line solved the problem. A new one on me.
  • rnrn Member Posts: 13

    does anyone know what the correct manifold pressure should be? I found the line pressure in the manual, but no the manifold pressure.

  • hrhr Member Posts: 6,106
    Did you

    remove and clean the spark rod and prove rod? Any blockage in the flue.

    I had this happen and found the roofer had set his coffee cup in the flue termination.

    hot rod

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  • JimHJimH Member Posts: 89
    ok ok ok

    slow down buddy, before you end up blowing your house up. first step, pick up a yellow pages telephone book. second step, look up plumbing/heating contractor in your area that has advertized 24hr. emergency service. third step, call them and explain that you have no heat and need someone to come as soon as possible. if they say that they cant get there until monday, try calling a different contractor until you find one that will come out to help you tonight. you are not trained to work on this equipment and should not be messing around with it .
  • rnrn Member Posts: 13
    i did

    i did remove and clean the ignitor. it had some white on it, but not bad. i also checked the intake/outlet lines....they're clear. this is a stumper.
  • rnrn Member Posts: 13

    this is good advice. I have contacted several hvac contractors and after going through several found one that had experience with Ultra's. After describing what I've tested and the results his advice was to have him come Monday when we can get Weil Mclain on the phone. Also, it is hard to get parts or the Ultra's around her and impossible outside of normal business hours. So, you'll be glad to know he is coming on Monday. I intsalled the boiler originally and have a healthy respect for things that go boom. My tests have been mostly visual and diagnostic/electrical.
  • rnrn Member Posts: 13

    10 w.c. I just measured it. so that checks out.
  • MitchMitch Member Posts: 549
    I have worked on several Ultras

    Give this note to your pro do not try it yourself.
    If you have changed the module and done so properly.
    and all flue and air piping is clear.

    Watch for any and all codes while trying to fire. At what stage does it drop out.

    Check air proving devices is the blower running and at the right speed.

    Check or change the ignitor/sensor if you cannot properly test it with a multi meter.

    Check for proper gas inlet pressure during the attempt to fire, outlet pressure is minimal.

    Check temperature readings from sensors if they do not look right you can have a bad sensor, try swapping inlet and outlet sensors.

    Check for proper ground and polarity.

    Try disconnecting the outdoor sensor.

    What is the condition inside the combustion chamber.

    Lots of stuff to look at but the more info on what it does before it drops out can help narrow things down.

    Good luck

    Mitch S.

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  • TonyTony Member Posts: 1,033

    The burner itself for blockage of the holes on the bottom.

    Gas flows but not near spark, no ignition. Condensation making it's way into burner has been an issue with some Ultras.

    Is this LP ? Noticed you said 10" w.c. for inlet pressure. Outlet pressure varies with firing rate.
  • FloydFloyd Member Posts: 1
    Russ... here's the problem

    Just got home, was away all day and checked my usual check on HH... anyway you have a tyrpical problem theat happens with the Ultra on LP....can't belive the WM tach. didn't tell you to do this.
    Reset your boiler then watch the frist digit on the left, it will go to A, then 5, then 1, then 2.... when it gets to 2 XXX,
    hold your hand over the horn inside the boiler. That is the air intake....don't hold your hand totally over it, about halfway should do the trick... don't be surprised if the boiler makes a bit of a pop when it lights off. You have air in the gas valve, and being that the LP is heavier than air the gas valve will not purge the air out. placeing your hand halfway over the "horn" will create enough of a vacum to pull the LP through the gas valve. BTW, you do have to remove the front cover to do this, and am assuming that you have done that anyway....
    Also your will not get 24V across the TT while the t-stat is hooked up and the t-stat is made.... but the t-stat must be working or your boiler would not be trying to fire.

  • rnrn Member Posts: 13

    > The burner itself for blockage of the holes on

    > the bottom.


    > Gas flows but not near spark, no

    > ignition. Condensation making it's way into

    > burner has been an issue with some Ultras.


    > Is

    > this LP ? Noticed you said 10" w.c. for inlet

    > pressure. Outlet pressure varies with firing

    > rate.

  • rnrn Member Posts: 13
    will check

    I'll check for condensation issues.

    This is an NP. The inlet pressure was 10" w.c. I don't have any specs on the outlet pressure. I am going to call WM tomorrow morning and ask.

  • It is now into the third day of this post, and we still do not know what the fuel source is. Russell, is it Natural Gas or LP? You posted that it is NP, and I don't know what that is.
  • rnrn Member Posts: 13
    make that NG

    NP...what can I say. It was late. It's natural gas.

  • 10" wc is within the tolerable limits for that machine, so that is probably not the problem. One question is: do you get an ignition spark? If you do there is a litany of items to be checked, if you do not, then it is most generally a fault of the electrode, the electrode cable, or the connections of the same. Have you checked the insulation of the electrode cable? Is there a solid ground connection between the ground terminal strip and the heat exchanger access cover? Let us know if you have an ignition spark or not.
  • rnrn Member Posts: 13

    There is visible spark. I've been getting support from WM today (they have been really great about support). The suspect right now are 1) the wiring harness to the gas valve. 2) the gas valve itself.
  • rnrn Member Posts: 13
    Ultra won't fire -- fixed

    It's fixed. Thanks again to everyone that responded. It was the gas valve. The WM folks didn't want to believe it was that. They apparently hardly ever go bad. I did get good support from them, though it was annoying that it was only weekdays 9-5.

    The final test they had me do was pull the condensation trap off and smell for gas when it was firing. I smelt gas when it pre-purged, but not when it tried to fire. My theory is that the low fire voltage was a byproduct of the stuck valve drawing to much current, but that's just my own theory.

    Here is the interesting part....7 furnaces within a city block of my house have has valves/regulators replaced in the last week. Suspicious. Could there have been some pollutant in the city gas lines recently?

    Once again The Wall was a great help. People gave great suggestions and there was fast response. thanks. I am listing the troubleshooting steps I was given for the ultra for the communities reference.

    The tests I performed (if you don't know what you are doing call someone in that does and let them test it)
    -check for spark visually
    -check intake and outlet vents for obstruction
    -check gas pressure
    -call WM
    -disconnect the outdoor sensor
    -unplug the low voltage cable from the blower and it should start
    -cover the air intake nozzle 50% during for a cycle to "burp" it
    -check the fire voltage (pin 9)
    -check the gas valve voltage
    -disconnect the condensation trap and smell for gas during ignition (be careful)

    thanks again.
  • rnrn Member Posts: 13

    I posted a full explanation further up in the original thread.
  • FloydFloyd Member Posts: 1
    Thanks for the update....

    That was a weird one.... for sure.
    But with anything mechanical or electrical weird is the expected....if it can go wrong it will at some point in time.
    Thanks for filling us in on the fix.
  • petepete Member Posts: 28

    Congrats on your repair, and you did it without blowing up the place. LOL..
  • Jay3776Jay3776 Member Posts: 1
    Ultra won't stay lite

    My boiler has had a lockout code E 02 after resetting the boiler will fire properly. I have observed that it ignite and then 5-10 seconds later will go out, it will go through the startup sequence and then attempt to start again. It may repeat the same way a couple times and then stay lite. Any suggestions.
  • ElkHunterElkHunter Member Posts: 1
    Floyd is the man!


    You are a genius! Fixed the problem just like you said, and the only thing I had to disassemble from both boilers was to take off the cover on each!
  • accumanaccuman Member Posts: 1
    Your advice is still working flawlessly....My heating guy who was not real familiar with Wiel Mclain could not get it to fire. I read this forum and coverd the horn air intake as you instructed and it fired imeddeimeddiately.....thank you so much you saved me aton!!!


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