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Help with Weil McClain Ultra! PSI fluctuation on startup?

Sketch Member Posts: 4
'Morning everyone!

Having some issues with a Well McClain Ultra. Woke up this morning to no heat, we have an inane amount of taco pumps to circulate sub floor radiant heat (14 or 15..someone took my parents for a ride!). When I woke up to a cold house, I  checked the boiler and saw a code "6-30" when I came to check. 6-burner off because temp setting has been reached. 30-temp rise across boiler over 58 degrees.

Turned the whole system off thinking it just needed to cool down, and (every time I tried this..3 times) everything starts up, codes go as they should (1.2..3..4..) but then it makes a series of "thumps" for lack of a better term. Sounds like it's trying to force water through and it's being blocked. PSI fluctuates between ~5-15 when it's doing this. It stops after about 15 seconds, but then within another 10 seconds gives me the same "6-30" code. Purged about 2 gallons of water from the system hoping it would do...something..but no luck.

I'm pretty handy, but don't know the first thing about boilers and heat. I truly would appreciate any help! Thanks!


  • Gordan
    Gordan Member Posts: 891
    Can you post pictures?

    It sounds like an air binding problem, with those PSI fluctuations and noises. What does the pressure read before you turn the boiler on?
  • Sketch
    Sketch Member Posts: 4
    Thanks for the response

    PSI is at 15 while it is off. What should I post a picture of exactly?
  • Gordan
    Gordan Member Posts: 891
    Piping around the boiler.

    And the boiler itself. Basically, to allow us to trace the flow of water and see all the major components that could be malfunctioning, places where air could be trapped, etc.
  • Sketch
    Sketch Member Posts: 4
    PSE&G Guy had a good laugh..

    I'll be able to post pictures when I get back from work in a a couple of hours. I've actually been wondering how to properly purge the system of air. 

    PSE&G worker came a few minutes ago and he said he's never seen anything like this, and said he couldn't even touch it.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    edited January 2011
    What could be funny?

    I have an Ultra 3, and you seem to have an Ultra 2, so yours must have been in there 2 years of more. So I wonder if your problems have been there always, or just recently.

    Are you measuring pressure with the little gauge on the front of the boiler? Normal piping for these has the boiler circulator pumping water into the return port of the boiler. The pressure gauge is on the output of the boiler, so it can read less due to the pressure drop through the boiler. I notice it most when the indirect hot water heater is asking for heat. I estimate that that circulator gets between 7 and 9 gallons/minute, and this drops the indicated pressure by about 3 psi. Where the makeup piping is  is in the secondary loop of the primary-secondary piping. Up there, the pressure change, if there is any, is not enough to cause water to be fed into the system.

    As far as purging air from the system, my near boiler plumbingg has a lot of ball valves and 3 boiler-drain valves (not counting the one that couled be used to drain the boiler). We turned off all the ball valves. We filled the boiler first. Then we opened a ball valve that delivered water to the indirect and opened its purge valve and let the water run until air no longer came out. We closed those two valves and opened the ones to the radiant (downstairs) zone and did the same thing. (Actually, there are 5 loops down there, and we did them one at a time.) Then we turned those off and opened the ones for the baseboard loop upstairs. We pushed the lever on the system fill valve to get maximum flow. That pretty much removed all the obvious air from the system. We ran it all summer for domestic hot water, and when I started heating the house in late fall, some air came out from somewhere (I assume the baseboard upstairs; there are no vents up there). So the air from upstairs was forced down by the flow, or dissolved up there and driven off as it went through the separator.

    P.S.: For you to get 58F temperature rise through the boiler, it sounds as though your boiler circulator is not running.
  • Sketch
    Sketch Member Posts: 4
    Pics and a little more info

    Gordon - attached some pictures, hope it helps. They're big images in case you need to look a little closer.

    JDB - Thanks for the info on purging the air. If there was air in the

    system, wouldn't I have heard it before now? Good point about the boiler

    circulator, not familiar enough with it to be able to check though.

    Could that be something like a blown fuse? For what its worth the first 6

    feet of pipe coming out of the boiler does get hot in that minute or so

    before boiler shuts down.

    Couple things from this morning:

    -checked the vents outside to make sure there wasn't snow, it was all


    -purged water on both sides of the boiler to check for air, seemed


    -Circulator pump for indirect water heater feed sounds like the impeller

    is out of balance. But even if it completely seized I should have still

    been getting water to the heating loop. Could there be an issue with

    the flow valves?

    -took the cover off the boiler to check all wires were connected,

    everything looked good EXCEPT a probe on the exhaust vent was melted

    loose. That obviously needs to be remedied before the system goes up and

    running again, but shouldn't be related to the errors I'm getting about

    outlet water temp, correct?
  • Paul_11
    Paul_11 Member Posts: 210
    I' having the same exact Ultra problem.

    Did you ever figure out what the problem was?
    Since 1990, I have made steam systems quiet, comfortable, and efficient. We provide comfort while saving the planet.

    NYC LMP: 1307
This discussion has been closed.