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Thread: problem filling hydronic weil mclain system

  1. #1

    Exclamation problem filling hydronic weil mclain system

    My son recently bought an older house with weil mclain gas fired boiler and baseboard heat. The system had been drained. We tried filling the system using city water and could not complete the fill - some air came out of the bleeders, but then quit, and no water was seen.

    All valves are open, but the pressure in the system is not high enough to drive water through. The pump was not operating.


    The fill line has a cylindrical device in-line (in, out, drain) with no adjustment that I assumed was an one-way valve to prevent back bleed (why does it have a drain?).

    The boiler has an expansion tank, and a large red device on top of the boiler that has an adjustment (handle or pointer), that I assume must be a regulator - but I don't know how to adjust.

    How can I get water into the system? I previously pressurized with air to test for leaks.

    Thanks!

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    The air scoops may be corroded and not letting air escape. You may have to find and replace. There's probably one inside the boiler, and there should be one somewhere on the line outside. There may be a bleed valve internal to the boiler somewhere also. Once you've used all of the bleed valves, and the system has tanken as much water as it can, you will probably need to then set things so the circulator will run, then do again. The instructions may be on their website if you can't find it in the manual. Often, these things come with two manuals...an installation one and an operator one...you may need both if they aren't combined.
    Jim DeBruycker
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    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Master Plumber nhmaster's Avatar
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    Fill valves get filled with crap and stuck closed from years of non use. Yours has no doubt gone south for the winter. Replace it and feel the joy.

  4. #4

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    Thanks for the reply - but i do not know what an air scoop is or how it operates. How can i identify it?

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    Retired Defense Industry Engineer jadnashua's Avatar
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    This has a couple of possibilities http://www.watts.com/pro/_products_s...=64&parCat=251

    A nicer one is made by Spirovent http://www.spirotherm.com/air/

    There are all sorts of others. It will likely sit in a T fitting, sitting vertially up, and have some cap or opening (it might be small) that will let trapped air out.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Member msgale's Avatar
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    to fill A system, you need water going in, enough pressure to reach highest radiator in the bldg, and a way for air to go out.
    i suspect you have problems in both areas.
    first, i would replace whatever valve controls water in.
    After your system is pressurized to about 15 or 20 psi, then check for air coming out as you open every single one of probably many vents .
    if no air or water, the vent is likely clogged.

  7. #7
    DIY Member msgale's Avatar
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    The fill line has a cylindrical device in-line (in, out, drain) with no adjustment that I assumed was an one-way valve to prevent back bleed (why does it have a drain?).

    probably it's to remove the clogged strainer inside and clean it

  8. #8
    Master Plumber nhmaster's Avatar
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    One last time. You boiler has an automatic fill valve. Probably a Watts S1156F but it could be a Taco 329. either way, it's gone bad, It's no good. It's functions have ceased. It does not work. It has bought the farm. Replace it. forget about your air vents or air scoops. Replace the fill valve. One more time. Replace the fill valve. Just to be clear. Replace the fill valve.

    So what are you going to do?

    Yes, replace the fill valve.

  9. #9
    Illinois Licensed Plumber SewerRatz's Avatar
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    I get a few calls to work on boilers. I refuse to mess with them since I do not know all the ins and outs of the systems out there. I just refer them to a plumber that does know boilers, be it hot water or steam systems. In other words I would say leave things to a professional if you do not have any idea what the parts of the system are, and how to adjust them properly.

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    Plunger/TurdPuncher kingsotall's Avatar
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    Ditto to what swereratz posted. Invest the money in a boiler mechanic and he can familiarize yourself with your boiler like no manual could ever do.
    I just post cuz I like to see my avatar.

  11. #11

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    Thanks for the suggestion. There are two in-line valves for filling, and both operate properly.

    The system has a "flo-control" valve (B&G) SA-1 1/4 which I gather is to prevent hot water circulation when the circulator pump is not running. Is this the valve you are referencing?

    Do I need this valve with baseboard radiators?

    Thanks.

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    Master Plumber nhmaster's Avatar
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    You need to call a professional at this point. I'm just about 1000% positive he will come out and change your fill valve. If the fill valve was working your system would now have 15lbs on it.

  13. #13

    Default Problem Resolved

    Thanks for all the suggestions - my problem was identifying the fill valve behind and under the expansion tank. I removed the internal valve mechanism and was able to fill normally - now I have to find an appropriate replacement. The flo-control valve was a non-issue.

    Incidently, I installed a 6 zone hydronic system 30 years ago (electric boiler) in my home, and subsequently added a home-built in-line wood source boiler - this system has worked flawlessly over the years.

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    Master Plumber nhmaster's Avatar
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    Imagine that

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    In the trades Dana's Avatar
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    Quote Originally Posted by Jim Cook View Post
    Thanks for all the suggestions - my problem was identifying the fill valve behind and under the expansion tank. I removed the internal valve mechanism and was able to fill normally - now I have to find an appropriate replacement. The flo-control valve was a non-issue.

    Incidently, I installed a 6 zone hydronic system 30 years ago (electric boiler) in my home, and subsequently added a home-built in-line wood source boiler - this system has worked flawlessly over the years.
    The relative value of automatic fill valves on hydronic systems is somewhat dubious IMHO. By auto-filling they mask leaks, often until there is water damage to finish or structural materials wetted by the leak. And they can leak fail/jamb, not really perform correctly, etc. They can be something of a "solution-problem".

    If you're boiler-savvy you can fill with the ball or gate valve until you hit the desired/necessary pressure then close the valve completely. Unless you have hearing issues, if there's a leak in the system somewhere and the pressure drops you'll detect the boiler's sizzle, buzz & bang soon enough- long before there's any hazard or damage. If you find yourself needing to top it off on a regular basis (even once/month is too much) you probably have a real leak, not just some spittin' air scoop or something- find it and fix it before it becomes a bigger problem.

    Checking the pressure should be on the annual maintenance checklist anyway, even with an auto-filler. Replace it if you like, but don't feel obligated to USE it.

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