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Inspector rejected coaxial venting

28W Member Posts: 141
My new modcon system (Vitodens 100) was installed with the Viessmann coaxial intake/vent tube.  Several recent installs in my neighborhood have similar setups.  But in my case, the town gas inspector is insisting that the intake and exhaust be separate pipes.  Any ideas why he might be requiring this now?


  • icesailor
    icesailor Member Posts: 7,265
    Coaxial Venting:

    What State do you live in?

    I think that the inspector is making up his own rules.
  • Tim McElwain
    Tim McElwain Member Posts: 4,580
    Show him the

    vent installation in the Vtiodends manual and that prevails.
  • Bob Harper
    Bob Harper Member Posts: 969
    approval of venting

    If the venting system complies with the listed instructions of the appliance then it can be used and he does not have the authority to require otherwise. The only exception to this would be where a local ordinance required you to opt for one iteration of the approved venting that exceeds the local snow line  such as in Mass. Even there, you can only use venting configurations listed for use with that appliance. 

    You have legal recourse and this inspector does have a boss. However, you must temper your response against the cost as this inspector's eyesight is sure to get miraculously a lot better once you've fought him.
  • 28W
    28W Member Posts: 141
    I'm in MA

    He also wants the vent at least 26" off the ground . . . above snowline, presumably.
  • 28W
    28W Member Posts: 141
    It certainly complies as currently installed

    But it is below 26" and I think there may be a snow line ordinance. Even if I need to extend the vent up above 26", I would much prefer a single pipe rather than two.
  • icesailor
    icesailor Member Posts: 7,265

    If you are a plumber or gas fitter in MA? If not, this was covered in the last CEU we did. If you are not a plumber or gas fitter but "A Heater", you are not supposed to be installing the venting. It is the responsibility of the person who took out the gas permit.

    That said, if you did the CEU, it was explained how you have to go to the Internet and find the snow fall level for your area and that determines the height of the vent outlet. He is correct that the vent termination must/may be 26" but there are being offered "snorkel vents". The dual outlet is much easier to get up above the snow line. If he is a legitimate Massachusetts Plumbing and Gas inspector, he should be well versed in the venting of gas appliances. They have to do far more CEU's than we do.

    If you are a MA Licensed Plumber, and have done the CEU, (I do mine through PHCC of MA) the first three hours are all on gas and far more comprehensive than the last three hours on plumbing. The board is really trying to get plumbers and gas fitters up to speed on gas regulations. The board sets the agenda of what they want taught in each CEU cycle. My last one (#4) was really heavy on chimney venting which I understood but not at the level that was explained. Especially on over-sized chimneys.

    IMO, you need to talk to Veissman and see what they say. Dual exhaust may just be more practical to install.
  • icesailor
    icesailor Member Posts: 7,265
    edited September 2012
    More Venting:

    Not if your area NOAA snowfall makes your vent outlet level below the snow line.

    As I said in a previous post, look at snorkel venting. I think that Veissmann stopped selling their brand of coaxial venting. Centrotherm may now make one. But I had a replacement to do and it was far easier to vent with two pipes than to have done it with a Coaxial vent. It was a "Mud Sill" foundation and couldn't have vented it with 2".

    Good Luck.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    Dig a pit???

    Can you dig a pit and drop a galvanized window well below the vent termination? I've had to do that a time or two in Denver, and the AHJ accepted it. Looks hokey, but less hokey than a double snorkel. Besides, it gives the garter snakes a place to hang out ;-)


    There was an error rendering this rich post.

  • icesailor
    icesailor Member Posts: 7,265
    The Pits:


    Not in Massachusetts. In fact. being in a "pit" would be below the published snow level. You could "snorkel" it up but not terminate below the snow level.

    I'll have to look in my last CEU book and get the requirements. I'll post later.

    We spent quite a bit of time on it because where I work, the snow will start with the wind from the South-East. Then, it goes into the North-East. The snow will be on the opposite side on the Lee Side. When the storm goes by, the wind will go North-West and blow the feathers off a crow bar. Then blow all the snow away. The snow drifts on the opposite sides of all wind directions. Very seldom will you get a snow fall with no wind. If the storm passes to the West, it will snow a huge amount and turn to rain which washes the snow away. If it passes to the east, it will be the heaviest snow in New England and stay as snow. .

    It's all foolishness. They want you to build for a 500 year storm/flood. The benchmark for the 100 year storm was the Hurricane of 1939. Now it is "The No-Name Storm" of October, 1991 AKA "The Perfect Storm".

    I don't know what the regs are in the land of Coors, but they don't sound as complicated as we have.

    But we work hard at stopping CO incidents.
  • Paul48
    Paul48 Member Posts: 4,469

    I think he was referring to adding a window well under an existing to give more clearance.
  • icesailor
    icesailor Member Posts: 7,265
    edited September 2012
    In the pits:

    I've gotten my classes information mixed up.

    The information about temperature was in series 4, outside chimneys and liners. And the location of the area where you had to find out the lowest temperature to decide what type of liner can be used.

    In 2011, I took a Veissmann factory class and the snow and vent termination was discussed there.

    In Veissmann's Installation Instructions for Vitodens 100's and 200's, for Rigid Pipe Venting Systems dated 2/2011, on page 21, it says:

    The vent must be installed observing local regulations in addition to National Codes, ANSI-Z223.1 or NFPA 54.

    A vent must NOT terminate...

    Section 4.  ....less than 1ft. / 0.3 m above grade level or anticipated snow level (consult local building authorities or local weather office). Locate the vent termination in such a way that it cannot be blocked by snow.

    The Canadian regs are basically the same.

    My aged brain is failing along with my body.


    But it was my understanding that the vent termination had to be 12" above whatever had been determined would be an expected snow level. With the sign above it.  
  • 28W
    28W Member Posts: 141
    I'm just a homeowner

    Question: if we swap out the coaxial vent pipe for a dual pipe setup, will both of the new pipes fit through the existing hole in the sill (that currently accommodates the coaxial pipe). I'd had to have an even bigger hole in the sill.
  • icesailor
    icesailor Member Posts: 7,265
    Hole sizes

    Usually, two pipes won't fit into the one larger hole for the Coaxial Vent.
  • gennady
    gennady Member Posts: 839
    snow line

    In NYC, fresh air intake must be minimum 36" above finish grade, to prevent blocking by snow. In MA i guess it should be no less. So, it is not about venting, it is about local code compliance.
  • Tim McElwain
    Tim McElwain Member Posts: 4,580
    When I worked for the

    gas company we set 30" as the height above grade. The blizzard of 1978 sort of set the criteria. Contractors liked having an exact height as they could do all the piping at rough in on new construction and remodels. I find some jurisdictions make things somewhat confusing in stead of making rules that make sense and then find a simple way to apply them.
  • Tim McElwain
    Tim McElwain Member Posts: 4,580
    It is important to remember

    that NFPA 54 as far as venting goes does not cover Category II, III or IV venting. That falls under manufacturers instructions. Now Mass takes some specific directions on venting due to an incident a few years back that killed a little girl. With that in mind along with the fact that they have there own code the CMR248 The Mass Code which incorporates NFPA 2002 (We are now up to 2012 code). The AHJ surely has jurisdiction so special classes have to be held to insure the word gets out. Those classes are mandatory and are for Plumbers and Gas Fitters along with special training for inspectors. They are very protective of those groups and have turned me down numerous times from doing any of the training as I am not licensed in Mass. I was many years ago actually on the committee that wrote CMR248 but anyway. All this means that installers in Mass should stay up to date with training and if it were me I would meet with the inspector at the job site before installation and get a list of what he wants up front. It is just the cost of doing business in Mass.
  • 28W
    28W Member Posts: 141

    In a two-pipe setup, how large (diameter) is each pipe? 
  • SWEI
    SWEI Member Posts: 7,356
    it depends

    On the BTU/hr rating of the appliance and the length of the vents.  The boiler manufacturer's venting manual will give you the specifics.  
  • 04090
    04090 Member Posts: 142
    How far from ground level

    How far from ground level do the inlet and exhaust pipe terminations have to be in Massachusetts?
  • MikeG25
    MikeG25 Member Posts: 1
    anticipated snow level website

    Does anyone know the website for the anticipated snowfall for MA?
  • icesailor
    icesailor Member Posts: 7,265
    Snow level data:

    Here's what you are looking for.

  • Charlie from wmass
    Charlie from wmass Member Posts: 4,250
    As Ice stated already

    The snow level is a town by town thing. In the northern Bershires and the Hilltowns it is higher than It is down near Fall River.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • icesailor
    icesailor Member Posts: 7,265
    Its also important to remember:

    Its also important to remember that Massachusetts isn't telling you how high to make the vent, it is the manufacturer. They all say 12" or .3 meters above the ground or above the snow level. Massachusetts only gives you a suggestion to where you can get the weather data that will give you a winter storm level that you can use. The importance of the CEU's for plumbers and gas fitters and the inspectors is to stop confusions over code interpretations and to keep inspectors, installers and the Board on the same page. It isn't perfect but it is a lot better than what went on before. If an inspector is wrong, the Board will stand with you. You can call any day during working hours with a code question and get answer.
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