Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Vent pipe condensate radiant boiler

wasteph
wasteph Member Posts: 7
Hi, I have a Weil-McClain boiler serving my hydronic system. The vent stack seems to be leaning against the drywall of the ceiling in the 20 year old house. I have no idea how old the system is, as we bought the house 2 years ago. It has often dripped a bit of water below and service tech last year said normal, hubby said normal. I bought a rubber mat to collect and figured the men knew best. Because most of the time you do!

Well, now the pipe is causing drywall damage to the ceiling of the basement, about 2" diameter circle, which I noticed because the condensation increased dramatically, from 2-3 Tbs puddle to 1/3 cup or so.

Hubby said no problem. It IS a problem. The drywall and probably subfloor of the floor above (system located in basement) are being damaged. The water condensation has doubled or tripled. That is different. Different is not good, right?

The vent pipe goes from basement through one entire living floor and about 6-8' of an angled attic, so a long run. We do live in a windy area. I can see some pine needle debris around the base of the plate mounting pipe to metal roof. Our roof is super steep and a pain in the butt since you can't really walk on it easily.

Hubby said he can fix it and will just "clamp the pipe into position" from Should I let him (he is very handy--and handsome--although 3 days went by when he was off and he ignored the green post-it reminder I left for him), call the service techs who did not do a good job last year and actually introduced water into my on-demand heater, or try and find a new tech. Help!

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 15,415
    None of this sounds particularly good. Can you take a few pictures of the situation? Do you any idea -- or could find out -- exactly what kind of vent pipe this is? There are a few -- a very few -- kinds which can be in contact with combustibles (which dry wall is), but …

    Some pictures.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • wasteph
    wasteph Member Posts: 7
    edited November 2019






  • wasteph
    wasteph Member Posts: 7
    Thank you. Now you have me thinking about combustible materials (before I was just contemplating drywall/wet rot/moisture ants or possible explosions from improper venting).
  • JUGHNE
    JUGHNE Member Posts: 8,191
    Do you have a drain hose connected somewhere to the bottom of the boiler or this vent pipe?

    The labels on the vent fittings might say 1" of clearance to combustibles.

    Does it drip only when raining.......or if boiler is cold......or if boiler has been running a while.
    mattmia2
  • wasteph
    wasteph Member Posts: 7
    It drips if it is running. This is the vent pipe, I believe that is against the ceiling. Hasn't rained in many days.

    There is another horizontal pipe that goes through crawl, PVC, that vents the gas. This unit make a big stink outside too where many comment we have a leak, but gas man says no and service man said no, just a not efficient unit. Hubby said the angle is not be best for the gas vent pipe but not changeable.
  • JUGHNE
    JUGHNE Member Posts: 8,191
    "The other horizontal pipe".....is that the 3" black pipe connected to the boiler where it says "air"?
    That is for combustion air to be pulled into the boiler and should have no smell at all. When it is running you should feel suction on the outside of that pipe......
    Do you smell gas at that pipe when the boiler is off?

    I had this type of boiler in my house for over 10 years. Never a bad smell outside. Mine vented out thru the wall and would run in the summer for hot water. We keep the windows open most of that season and it was never noticeable.

    Did you locate the drain hose for the vent pipe, it may be on the floor under the boiler and should pass a fair amount of water when running. My unit was a little older, but I think all of these has a drain hose at the bottom of the boiler venting system.
    BTW, this should be a fairly efficient unit.

    Pictures of the roof cap and the air inlet pipe please.
    Also lower side of the boiler where the vent pipes connect.
  • CBRob
    CBRob Member Posts: 182
    edited November 2019
    Don't these boilers have a built in mixing valve ( side by side circ pumps) to keep the return water hot enough to not condense the flue gases?

    Looks like a gold gv

    Return water temps are to be kept up to 140 by way of the circulation bypass pumps.


    Maybe the water temps are going low enough to condense the flue gases, or the fan is getting weak enough to not push the exhaust out fast enough.
    I've got a home that I manage with the same boilers, no condensate on the exhaust at all and with cold outside temps.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 1,832
    @CBRob WM Model GV Series 1 has the mixing valve, and it is probably failed by now, at 20 years old. BTW mixing valve are not available from WM anymore. There is a service bulletin addressing that.

    Series 2 and after uses a second circulator to keep return water temp high enough to prevent cond. of Flue Gas inside the boiler flue passages.

    @wasteph The condensation from the metal vent pipe may be flue gas leakage. See the "red silicone caulk" around the joints of each fitting. This is the first version of AL 29-4C® stainless steel venting. (Now it comes with gaskets on the female opening). IF THE JOINTS ABOVE THE CEILING DON'T HAVE THE RED SEALANT, or the sealant is failing to maintain the original seal, or the vent pipe has settled and caused a seal to fail, there is a good chance condensation is leaking out with a small amount of Flue Byproducts (exhaust gas). The leak will increase as the condition continues to progress with age.

    You will want to open the ceiling near the water damage and inspect the joint. You want to get that fixed ASAP, if my guess is accurate.
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
    CBRob
  • wasteph
    wasteph Member Posts: 7
    I have a call into a service person, they come Monday. They are not "Certified" for that brand, only 2 places nearby if you call 1 hour away close. I was tempted to use them anyway, although they also do commercial stuff since they are linked from the boiler manufacturer site.

    Thanks for the heads up and info. The leaking area is coming from above the ceiling in the chase which is framed and drywalled up 2 more floors, so will be a pain if it is leaking in this drywalled "chimney" area. Hubby says you would assess the pipe to see if the red silicone caulk has failed from the chimney side but he does not have a tall enough ladder to access the roof. He did cut the drywall back a bit, so at the least, the pipe is not touching/leaning against it in the interim. He keeps saying it is condensation but no big deal.

    @EdTheHeaterMan, I hate to think it is the mixing valve and we can't replace it. That sounds like a new boiler. Could a machine shop friend manufacture one???

    I will have to take pics tomorrow, sorry. Dark and so many things on my list.
  • JUGHNE
    JUGHNE Member Posts: 8,191
    There is a bulletin about a fix for the mix valve.
    You can download the install and op manual for this boiler.

    The drain hose/opening is a main concern.
    If for some reason it is plugged then the water may be pushed up the exhaust pipe but it seems the pressure switch should shut it down.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 1,832


    This is the bulletin for the mixing valve problem, you just need to repipe a bypass loop/pump if you have cast iron rads. If you have baseboard then you just need to block the opening, or cap off the 1/2" nipple that connects the mixing valve.
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
  • rick in Alaska
    rick in Alaska Member Posts: 1,165
    If the exhaust system has intact gaskets, then there should not be any exhaust or condensate leaking out the pipe. Unfortunately, I have not seen very many exhaust systems that have gaskets in them where the gasket wasn't compromised somehow. But even still, if the pipe is installed correctly, the male end of the pipe should be pointing down, so if it did have any condensate coming down the pipe, it should just drain all the way down inside it, and not get out. Another thing is that I am pretty sure there should be a special Tee at the bottom of the chimney just before it goes in to the boiler that has a small nipple on it where you would hook up a condensate drain line with a p-trap. This is to keep condensate from getting back in to the boiler.
    I would try and find out if the water is coming from the very top of the pipe where it exits the roof. I t very well could be it is condensating around the outside of the pipe due to it being in a chase that is allowing warm air to get in at the ceiling level in the boiler room. If the chase is cold, and the pipe warms up when it is running, it can condensate on the outside. If that is the case, then you just need to put a trim plate on the pipe where it exits the room and seal it off. It should have been there anyway for fire code.
    Rick
  • wasteph
    wasteph Member Posts: 7
    Okay, it seems to be leaking from right above the basement ceiling. We cut into the chase on the 3rd floor and no water from roof is apparent. We also cut into the drywall and you can see the water leak right above the ceiling. They are saying ducting was not installed correctly, was cut into pieces when it should not have been and also a gasket must have failed. Going to redo ducting and I think just get a new boiler too since newer ones (this one is 21 years old) would require different ductwork that is not compatible with Level 3 this one requires. Plus, the way they built the chase will be impossible to replace and we will have to reroute it the ductwork regardless. Don't want to pay for ductwork 2 times if/when boiler gives up the ghost. Here's crossing fingers newer stuff is built okay, as I often feel the "olden days" had better quality. Thanks for all the help. Maybe I can get it done before Xmas.
  • JUGHNE
    JUGHNE Member Posts: 8,191
    You can vent this boiler out a side wall with SS piping, the air inlet can also be next to it.
    Any new condensing boiler you might get can be vented thru sidewall with PVC piping.

    Did you ever find a drain hose for the boiler or the bottom of the vent/exhaust piping?
  • wasteph
    wasteph Member Posts: 7
    Yes, it has a drain hose. They plan to vent out the sidewall and I will have roofers I guess come and put a cover or something instead of the roof vent chimney? Steep metal roof so a real PITA (pain in the a--) I am assuming they can seal 'er up. Thanks, again and happy holidays!
Sign In or Register to comment.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!