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Weil McLain CGi Series 3 - rust corrosion and possible leak

ChaseB
ChaseB Member Posts: 3
edited December 2021 in Gas Heating
Hello
I have a two year old Weil-McLain CGi Series 3 Gas fired boiler. Took the front cover panel off to check the unit and found rust. The area is dry at present and the rust is only in a small area. It seemed to be a very poor location for the rollout thermal fuse element as a leak can just pour on to it. My question is should I be concerned and could the rollout thermal fuse element be damaged.



Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,453
    Can you post some pictures of the boiler and the piping? Stand 8' back and 3-4 pics should do.

    I would suspect maybe your return water temperature may be too low causing condensation unless you see something leaking.
  • ChaseB
    ChaseB Member Posts: 3
    Hope this shows enough piping.




  • kcopp
    kcopp Member Posts: 4,419
    Roll out fuse is perfectly placed.
    You have more issues there than that.
    As @EBEBRATT-Ed mentioned your boiler is not piped properly.
    You must have a lot of cast iron radiation in your home and it takes a long time to heat up that water.
    The boiler is condensing and causing the boiler to "sweat".
    Long term this is killing the boiler..

    It needs to at a minimum have a bypass piped in ... prob best piped primary secondary to protect the boiler and a thermal control so the boiler does not stay in condensing mode for long periods of time.

    Furthermore I think the venting is wrong... The boiler is common vented w/ a natural vented water heater. Boiler is power vented.
    Not sure that is allowed.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,453
    @ChaseB

    I think the issue with the corosion is low return water temperature. The boiler return water must be above 130 degrees to prevent issues. The general rule is on a cold start the return should get to 130 within 15-20 min or so.

    By looking at your piping I can see that you have a converted gravity system with large cast iron radiators. I can tell that because if you follow the piping coming out of the boiler (the 1 1/2" copper pipe) it changes to like 3"? black pipe.

    There are several ways to fix this. IMHO a 3 way valve with a control sensing boiler return water temp is the best fix although Weil McLain has other ideas

    I attached a boiler manual it's for a series 4 not a 3 but they are pretty much the same . See pages 21-29 where they discuss low temp return water.

    Your installer should have taken care of this. If you need a contractor try "find a contractor " on this site or post where you are located someone may have a recommendation
  • ChaseB
    ChaseB Member Posts: 3
    Just so I understand. If this problem is due to return water temperature, would it occur all the time or intermittently. I have been monitoring the area over the last two weeks and there has not been any moisture in the area or in the fiberglass above the rust area.
    Just for the record I did not install the furnace it was done by a company that specializes in boilers.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,453
    @ChaseB

    Understood that you didn't install it. All cast iron hot water boiler manufacturers have language in their install documents where they show recommended piping and then they state something like this: "manufacturer should be consulted for recommendations if the boiler is installed in systems with unusual piping requirements"

    It's something the installer should have caught.

    This problem is more likely to happen in the spring and fall when the boiler has more cold starts. During cold weather when it is on more often not so much.

    Check it from time to time, you may want to pursue this next summer
  • Shane_2
    Shane_2 Member Posts: 191
    edited December 2021
    I would also suggest taking off the top jacket and inspecting the pipe connections at the top. 4 Phillips screws and you may need tin snips if the boiler was never properly serviced before.

    There is a built in air scoop in the CG series where the installer piped the expansion tank, with the weight of the tank and piping, it would be worth a look.

    I usually install a nipple and key vent there and use an air removal device and pump on the supply side (Thank You Dan H.)

    The condensation issue and venting should also be addressed as others have mentioned