Gas h2o heater sizing, new installation

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jparrie, Jan 21, 2008.

  1. jparrie

    jparrie Automotive Locksmith

    Messages:
    17
    Location:
    California
    We are doing a complete rebuild on our home, and I'm looking for advice on what to use for water heating. The plans call for a Tankless unit in the attic, but after much research, I'm not sold on tankless. The final straw against tankless is I have better things to do than flush out the water heater 2 to 4 times a year.

    I would like to keep the water heater in the attic location as it is very central to master bath, office bath, guest bath and kitchen pretty much eliminating the need for a circulating system. The roofline in this location allows approx 5'-7" between the base for the tank and the roof sheathing. My plumber tells me that a 75 gallon tank would have enough capacity for our needs. He is not aware of any low profile 75 gallon gas heaters.

    Questions:

    1. Do you think 75 gallons is adequate? There are two full baths, two half baths. Kids are grown and gone, day to day use is my wife and myself. We rarely use a tub, but the master bathroom will have body sprays and a rain head.

    2. Are there any low profile gas heaters made, or would a standard 75 gallon have enough clearance to be ok in this location?

    Any other concerns? I would definately install a catch pan under the heater with drain piping to the exterior of the structure.

    I would really like to keep the heater in this location, as the design allows for this area to contain the forced air unit, network hub, catv hub, whole house exhaust equipment, etc and it would be great to have all this equipment in the same place.
  2. BAPlumber

    BAPlumber Plumber

    Messages:
    227
    Location:
    Vashon, Washington
  3. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,718
    Location:
    Central Florida
    One concern I'd have would be the loading on whatever surface supports the water heater. You're looking at over 200 pounds per square foot, and I doubt any residential attic is designed for that static load.
    Last edited: Jan 22, 2008
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,153
    Location:
    New England
    I'll second Mikey's comments. A WH generates a fairly concentrated load - you may need to beef up the ceiling joists, or ensure it is placed over a load bearing wall. A full 75-gallon tank would weigh over 600 pounds - probably in the order of 700 (about a 100 for the tank, which may be low).
  5. get a 50 gallon and be happy

    Instead of a 75 gallon which is almost too big
    for both of you ,

    just go out and get a 50 gallon RHEEM gas hot
    water heater with a 65,000 or 75,000btu burner...
    ( I cant remember which it is right now)

    that is much smaller, and yet the thing heats
    as fast or faster than a 75 can........


    the cost is less than a 75, but more than
    a normal 50.....


    all it needs is a 4 inch chimmney.....

    ww have put in a few and never have heard a peep
    from anyone about running out of water.

    its basically like a glorified boiler
  6. jparrie

    jparrie Automotive Locksmith

    Messages:
    17
    Location:
    California
    All good feedback, exactly what I was looking for. Thanks guys!

    I have my architect looking into the weight issue.

    MP Mark, do you happen to know the height dimension of the Rheem tank you're talking about?
  7. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
  8. Standard height...

    I think it is a normal stardard height...

    you will have to call around.....


    Bradford White makes a LOW BOY 50 gallon

    gas heater comming in around 49 inches tall....

    Call some Bradford Dealer and see what they have

    available in the larger BTU input levels....


    either way you go you will still be much much cheaper
    than the tankless ...
  9. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,718
    Location:
    Central Florida
    Also have your architect ensure there's sufficient access to remove & replace the thing in 15 years or so...
  10. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I am not a fan at all of WH in the attic. First: climate. Are you somewhere where freezing of pipes would be an issue? Second, are you somewhere very hot, like Texas or the Southwest? There are known issues keeping pilots lit in extreme hot attics. Third, the consequences of a major WH leak from the attic are enormous.
  11. jparrie

    jparrie Automotive Locksmith

    Messages:
    17
    Location:
    California
    Climate is mild, no frezzing issues, summer temps rarely exceed 95 degrees.

    The possibility of a leak has me concerned as well. I'm not in the trade, so my experience with leaky water heaters has been limited to my own and those of family and friends. I have never seen anything more than a slow drip from a tank or a small stream from a tired relief valve.

    Assuming that the relief and a drip pan are properly plumbed to outside the structure, what should I be worried about?
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,153
    Location:
    New England
    If you've got a good pan and its drain is not plugged, one hassle is that you might not see that it is leaking for awhile. And, in SoCal, you have to anchor the thing for earthquakes...not that much in an attic to tie it to reliably. This is just a guess, that may be a problem with the inspector all by itself.
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