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How not to vent a Gas condensing boiler


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Comments

  • SuperTechSuperTech Posts: 938Member
    Lol. It just needs a little more RTV
  • nibsnibs Posts: 341Member
    Thought I locked the door before I left.
  • Jean-David BeyerJean-David Beyer Posts: 2,632Member
    Do not gas condensing boilers require two "vents," one for air supply and one for exhaust, so that the differential pressure between them is extremely low?
  • nibsnibs Posts: 341Member
    My Rinnai E50 allows for using room air.
  • SteamheadSteamhead Posts: 13,203Member
    Once again- you can't fix stupid!
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
  • IronmanIronman Posts: 5,144Member
    Are you kidding? What idiot did this?
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • JUGHNEJUGHNE Posts: 5,852Member
    Any pictures of the rest of the install?
    Homeowner job?
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,951Member
    edited January 11
    Probably not a homeowner. Most of them have more sense.
    RTV coated flue. Must be a new design.

    I am surprised the off gassing from the curing RTV didn't take someone out.
  • GrallertGrallert Posts: 330Member
    I think that Viessmann allows for room air, I guess that's why the cover is off.
  • LeonardLeonard Posts: 840Member
    edited January 22
    that RTV burns,

    not knowing any better I used it to line a rusted exhaust suction fan cavity on a Carrier nat gas flat roof HVAC unit we owned. When I tested it red hot burning bits of red "fire-proof" RTV blew out........ I replaced it.
  • Do not gas condensing boilers require two "vents," one for air supply and one for exhaust, so that the differential pressure between them is extremely low?

    Grallert said:

    I think that Viessmann allows for room air, I guess that's why the cover is off.

    They could also have removed one or two of the rubber flaps on top of the boiler to allow air in.
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
  • mikeg2015mikeg2015 Posts: 899Member
    edited February 2

    Do not gas condensing boilers require two "vents," one for air supply and one for exhaust, so that the differential pressure between them is extremely low?

    We use room air on most install of furnaces and boilers unless it’s a very tight home. Too many service calls for plugged intakes to make it worth the minimal impact or the cost of extra piping. Code requires it on some cases.

    But code book writers and inspectors don’t have to clear frozen intakes when it’s -15F outside in 2’ of snow.
  • NY_RobNY_Rob Posts: 1,370Member
    edited February 2
    If you're venting with PVC and are in an area where snow buildup/blockage is a concern, you could always install a Cleanout Tee with Cap in the intake piping and just remove the cap for as long as needed if it becomes necessary. No going outside to shovel.

    FWIW- I have read regarding mod-cons that it desirable to use outdoor air for combustion vs. indoor air whenever possible because the outdoor air is generally "cleaner".

    https://www.supplyhouse.com/Spears-P444X-030-3-PVC-DWV-Cleanout-Tee-w-Standard-Plug



  • mikeg2015mikeg2015 Posts: 899Member
    Outdoor air is cleaner so long as there’s no grass clippings. But lint and dust would be less and chemicals depending on location. Downside is bugs getting in. We’ve just found we have dramatically fewer issues using indoor air all around and of course you can offer a slightly lower installed price.

    The clean out is a good idea on longer runs.
  • SlimpickinsSlimpickins Posts: 322Member
    When it says it allows room air you first have to do the math and determine if you have enough cubic feet to allow it. You're really doing your customer a dis-service by not bring intake air into the appliance unless it's absolutely impossible.
  • LeonardLeonard Posts: 840Member
    Seems a plus to using interior air in cellar is ventilation ..... if have radon, mustiness, etc......
  • ChrisJChrisJ Posts: 10,030Member
    edited February 22
    Not that I'm defending this disaster but most red RTVs are rated to be used at 600 degrees F and the only "off gassing" would be acedic acid which smells like vinegar from the RTV curing. Once cured I wouldn't expect any smell.


    I wouldn't think you would be venting at 600+ into that vent.

    Like I said, not defending anything in that picture.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • mikeg2015mikeg2015 Posts: 899Member

    When it says it allows room air you first have to do the math and determine if you have enough cubic feet to allow it. You're really doing your customer a dis-service by not bring intake air into the appliance unless it's absolutely impossible.

    It’s not a disservice if there are fewer call backs that way. These are not tight construction cookie cutter modern homes.

    That combustion air gets heated regardless of where its introduced, direct or indirectly. So there no change to net system efficiency.

    We use 2 pipe where it’s nessesary. Most of these installs were previously B vent or chimney vent furnaces at one time, and most were just gravity coal furnaces before that.
  • plumbbobplumbbob Posts: 12Member
    whats wrong with it it looks great :)
  • TimcoTimco Posts: 2,928Member

    Can I play?
    Technical Support Manager, HTP Comfort Solutions.
  • TimcoTimco Posts: 2,928Member

    I'll add this beauty....
    Technical Support Manager, HTP Comfort Solutions.
  • Jean-David BeyerJean-David Beyer Posts: 2,632Member
    And the inspector passed this?
  • ChrisJChrisJ Posts: 10,030Member
    > @Jean-David Beyer said:
    > And the inspector passed this?

    That's a 50 50.

    Are you surprised if one did?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Leon82Leon82 Posts: 618Member
    > @Timco said:
    > I'll add this beauty....

    Is the intake teed into the exhaust?
  • Leon82Leon82 Posts: 618Member
    It's like they saw a diagram of the concentric vent and moved it to there.

    That couldn't have run more than a few seconds before it started convulsing
  • mikeg2015mikeg2015 Posts: 899Member
    Leon82 said:

    It's like they saw a diagram of the concentric vent and moved it to there.



    That couldn't have run more than a few seconds before it started convulsing

    You think they opened the manual?


    Easy fix since it’s not newer tight construction. Just make it 1 pipe.... assuming HTP/Westinghouse allows that.
  • Jean-David BeyerJean-David Beyer Posts: 2,632Member
    Are you surprised if one did?

    Not really. One inspector approved my new heating system when there was a 12 foot (or so) long piece of bright yellow CSST gas pipe going straight across the garage (where my heating system is) that was neither bonded nor grounded. A different inspector approved the condensate drain just dumping the condensate on the ground outside. Another inspector ... . The list never ends.
  • TimcoTimco Posts: 2,928Member
    Leon82 said:

    It's like they saw a diagram of the concentric vent and moved it to there.



    That couldn't have run more than a few seconds before it started convulsing

    And it did not...We do allow for room air intake and there are provisions in our manuals for that, and tables showing required openings to rooms that do not provide enough free air or space. Clearly they saw a concentric and said I can do that! Same pipe is easy!
    Technical Support Manager, HTP Comfort Solutions.
  • NutjobNutjob Posts: 1Member
    ChrisJ said:
    In vehicle exhaust systems this would be scavenging - moving exhaust flow from a small diameter pipe to a larger diameter. But what do I know? I'm not a plumber.

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