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Tankless heater proximity to gas meter

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motomars
motomars Member Posts: 14

Hi all. I'm trying to plan the location for a tankless gas water heater and the ideal spot is close to my indoor gas meter (see pic - note the that W/D hook-up is being removed). I've read that the meter should have a 36" clearance to any combustion source, however in my case the service regulator is located outside the house. Does this affect the clearance requirement? Assuming adequate space is allowed for service work on the meter, is there any concern with having the tankless heater closer than 3' to the meter? Thanks

Mad Dog_2

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  • pecmsg
    pecmsg Member Posts: 4,883
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    That 3' clearance applies to the meter itself. They can't service it if its blocked!

    Mad Dog_2motomars
  • ChrisJ
    ChrisJ Member Posts: 15,768
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    I guess that doesn't include washing machines according to the 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
    Mad Dog_2pecmsg
  • motomars
    motomars Member Posts: 14
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    Thanks - makes sense about the service blockage. So is it fair to say that there's no concern about a "combustion source" being close to the meter itself? More specifically, that receptacle at the lower left of the meter can remain? (As I mentioned, the washer/dryer is being removed.)

  • Teemok
    Teemok Member, Email Confirmation Posts: 511
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    From my reading that outlet is considered an ignition source and must be 36" away from the meter. Any switch, relay, outlet or device with a spark igniter would be an ignition source. All the wording says "meter" and doesn't mention or differentiate from the regulator vent. On some diagrams the supply riser pipe seems to be the center from where 36" is measured and not the the meter or regulator itself. That said here's a picture provided by PG and E showing a 36" radius from the regulator vent outlet. Confusing. If your regulator is outside and the meter is inside there might be different rules. Check with a local authority is my advise.

    Mad Dog_2motomarsIntplm.
  • Jamie Hall
    Jamie Hall Member Posts: 23,426
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    There are two completely different considerations here — which may be part of the confusion. The fire protection people are, understandably, concerned about the distance from a regulator vent to an ignition source. However, the meter regulation isn't concerned about ignition — it is concerned about maintenance.

    As I read the initial the concern is about the distance from the meter to — in this case a tankless heater. Whether it's a tankless heater or not, as I read the code, makes no difference. You need three feet clearance around the meter. From anything except possibly a wall in back of it.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Mad Dog_2TeemokmotomarsIntplm.
  • Teemok
    Teemok Member, Email Confirmation Posts: 511
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    The blocking distance seems clear cut enough given that you know where to measure from. The fire concern with the regulator being outside is what I'm unsure of. The regulator seems to be the primary fire concern and a 36" radius from the vent is very clear but maybe the meter itself is also a fire concern and for simple rules the distance is same, 36". 36" from the center of the supply pipe union connection or the meter body or any edge? The closest ignition source in a tank-less heater might be the pcb board relays on the far side 36" away where the measurement starts. Inspectors have discretion to look at it and ok what they determine meets the intents of code.

    motomars
  • Jamie Hall
    Jamie Hall Member Posts: 23,426
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    Let's just go back to square one here.

    @motomars , could you find the relevant section of the code? You said "[you've] read somewhere that the meter must have a 36 inch clearance to a combustion source". Words matter. A lot. is it the meter, or is it the regulator? If it is the meter, that's pretty unambiguous — and a tankless heater is indeed a combustion source. Since it does not apparently specify where on the meter the measurement is to be taken from, the only meaning (at least the one I would have enforced) is from the nearest point anywhere on the meter to the questionable clearance. Or, in simpler terms, there must be a clear distance from the ignition source — which I would have interpreted as anywhere on the tankless heater — to anywhere on the meter of at least that 36 inches.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    motomars
  • pecmsg
    pecmsg Member Posts: 4,883
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  • motomars
    motomars Member Posts: 14
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    @Jamie Hall, I've found slightly conflicting information. The relevant local reg says "[Indoor] Gas Meters are located in a ventilated place not less than three (3) feet away from a source of ignition or source of heat which may damage the gas Meter…" That seems fairly straightforward and it's essentially repeated in the gas utility's Contractor's Guide. However, the guide goes into more detail and its discussion about source of combustion clearances specifically references the regulator and regulator vent.

    Ultimately, going by the letter of the law, I should probably move that receptacle. Or I can eliminate all concern (and free up some basement space) by having the utility move the meter outside. Thanks all for the input - very helpful.

  • pecmsg
    pecmsg Member Posts: 4,883
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