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CMadatMe Member Posts: 3,086
Is anyone aware of a nat gas condensing boiler  285K input that can vent 3" CPVC , 110' combined length, is 96% AFUE and has a 5 to1 turndown ratio?

Went on a job site visit today for a bid that is due. Those are the specs in the bid and they do not want the flue's touched. Flues were originally put together on the sidewalk, craned and dropped down the chimmney then cemented in..There are SIX of them. Job has old HydroTherm Multipulse boilers. At first was thinking Knights but that isn't happening with the vent issues..

"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Scary way to engineer a job.

    I know of none, but that does not prove anything since I am not a contractor. I know of one that comes close, but requires 4" pipe.

    But what if there are no boilers that meet that specification? The architect or engineer of the job should be able to name at least one boiler that meets their requirement, and my guess is that he cannot.

    I wonder who gets to pay for the retrofit on the intake and exhaust system.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Chris, I have a lot of I an O manuals on all kinds of

    equipment that may be able to handle those requirements. How big a rush on this as it will take some time to research?
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Have a Week


    I got the bid that was due on the 4th extended one week. These guys have no clue. I went there with one of my contractors as a favor. If I didn't open my mouth and press the issues this job was headed for trouble. This job is funded with state dollars and to pull information out of them is like pulling teeth. While driving to the job and reading the scope of the bid I already had many concerns.

    It gets even better. Existing are 4 300,000 boilers thus the 1.2 in the spec.Walk in the boiler room, look at the piping and one can see they don't need it. The funds for this come from an Energy Efficiency program thus why they want 96%. I could care less about what's there and want to know if anyone did a heat loss of the building and have existing lengths, dimensions and types of emitters. Find out yup someone did but it wasn't divulged in the spec. Talking to the building management I find out they have been running on 3 of the boilers all heating season (1 is done) with no problems.

    I then ask if anyone has gas bills over the past 2 years and low and behold yup. They have therms used for the past 2 years. They also have another two fo the same boilers doing domestic and want them replaced. Again find out been running on 1 with no problems. So I asked has anyone calculate the actual domestic demand on the bldg. Yup....

    The point here is that they did the leg work but still just put it out to replace exactly the btu amount that is sitting in the basement. Building owner showed up well into the conversation and by the time I was finished he wasn't looking very happy. I am suppose to recevied on Monday, the actual heat loss that was done, the therms used in the last two years as well as the actuall domestic demand

    My concern about types of boilers that are avail based on my original post was I don't think there are any and stated that there is no boiler that will meet the spec. If you look at the spec they are telling you Lochinvar Knight without specifically stating the actual boiler. By law they cannot spec a specific product mfg and you have to be good enough to figure it out. Which I of course I did because thats exactly what they wanted. Too bad it vents 4"  nice application for it.

    Did I say the boiler room is real small which is also an issue.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    edited April 2011
    Try Lochinvar....

    I think that sounds exactly like their boiler. I think it is called a 286 now, but is still 285K in. New number reflects new control logic.


    EDIT: Lochy won't cut it either. Requires 4" and limits 100' (which you said in your second post, DUH ME...)

    Here's a link to their specs.


    You MIGHT be able to convince their engineers to allow you to use 3", but the appliances will automatically be derated.

    Camus might possibly work, but they are Canadian, if that matters. I remember something about all Federal dollars requiring either manufacturer or assembly in the US of A, but that was early on, and like the Health Care, people are probably asking for exemptions to this rule as well....


    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Thanks Mark

    I might just send them the venting and try that. Boilers shoot about 15' straight to a corner and then b-line straight up five stories.  
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • hot_rod
    hot_rod Member Posts: 16,557
    one of the mod con

    brands had a de-rate formula for venting into old 2" HydroPulse vent systems, but the AHJs were frowning on it and they were concerned who would be responsible for any issues.

    If it's worth doing....

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SpeyFitter
    SpeyFitter Member Posts: 422
    Try IBC

    IBC's VFC 45-225 (45,000 to 225,000) Natural Gas Mod-con boiler can vent up to 240' on the exhaust and 240' on the intake if needed (240' each side), on 3" CPVC S636 ( CPVC S636 for the exhaust, you can use 3" ABS or PVC for the intake) with a 5' equivilent allowance for long sweep 90's and 8' foot equivilent allowance for short sweep 90's.
    Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited April 2011

    It would be worth the look to see what these boilers are actually delivering. They do have 4" vents coming off the boilers but were reduced to 3" after 24" or so. Plus one of them wasn't even working this past heating season and the building heated fine. Boiler room space is an issue to use smaller boilers unless we can get the load down to boilers that vent 3". The link is the building. Flue would be down on the right hand side of the bldg out the roof just at the 3rd car in.

    There are no engineers to speak with. Project is being run by a Affordable Housing Conservency that provides monies to convert to high efficiency.

    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • CMadatMe
    CMadatMe Member Posts: 3,086

    Tried that. They are not 96% AFUE. Don't meet the spec. One of the other issues I have. We are limited on boiler choice because of the 96%. I did propose that they give that a second look and bring it down to 95%...
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Steamhead
    Steamhead Member Posts: 15,429
    Might be best to walk

    this sounds like the typical no-win situation. Life's too short...............
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Not Yet

    Trying to get them to do the right thing. Contract out having the existing vent system removed. Install a couple of 120 gal electrics for temp dhw. The demand is not large in the sense of multiple fixtures at the same time. It may not give them exactlt what they need but would get them buy for a week. I also asked them to provide the heat loss in the spec versus just the exisiting btu loads off the boiler tags. Same for domestic. Want the demand/load. There are 6 boilers there and based on the building running without any problems on 1 down heating boiler and 1 down DHW boiler we could combined dhw and heating into one bank of condensing boilers. Would make the footprint smaller and provide them the best bang for the buck. I think the bldg owner sees that is the best way to go. Will find out Monday am..
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • icesailor
    icesailor Member Posts: 7,265

    Nice solution to a complicated problem.

    Done the way it should be done.

    Congrats to a well thought out potential solution.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Yes Scott

    that had entered my mind when Chris asked for a match up. I had looked up IBC this AM and agree with you. I would hope the 96 versus 95 is a small issue, but who knows.

    The issue may also be that it is not a USA boiler which may cause more concerns.
  • scott markle_2
    scott markle_2 Member Posts: 611
    edited May 2011

    Hope your able to influence this one in a positive direction.
  • scott markle_2
    scott markle_2 Member Posts: 611
    edited May 2011
    cemented in

    The fact that those vents were cemented in sounds like trouble, to remove. Could it also be a bad practice by not permitting expansion and contraction.

    If you could use indoor air you could halve your vent length. If removing the cemented vents is impossible maybe some kind of controlled outside air supply for the boiler room is an option.

    I was curious about the vitdens cpvc venting requirements but couldn't find the specs. As I recall the 100 could do 80ft of 2''. If the restaurant could use a wall vent instantaneous maybe 6 120k boilers could do the trick?
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