Room with gas water heat really hot

Discussion in 'Water Heater Forum, Tanks' started by ed5cgs, Jul 15, 2014.

  1. ed5cgs

    ed5cgs New Member

    Messages:
    5
    We recently had a 25 year old 50 gallon gas water heater replaced with a Bradford White with a direct vent. The water heater is in the laundry room which is about a 8 x 8 room inside the house. What we are now noticing that when the laundry room is closed, that room gets really hot. The source of the heat is the water heater (no laundry had run and the room heated) as it heats water. When I touch the vent, it's really hot. The vent appears to be about 4" in diameter. Do the newer water heaters run that hot now?
    Is there a way to keep this cool ? Do I need add a vent?
  2. Terry

    Terry Administrator Staff Member

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    14,992
    Location:
    Bothell, Washington
    Can you post a picture? 800 pixels or less
    A true direct vent water heater has a covering over the vent, and is about 8"
    A model number too of what they installed.
  3. ed5cgs

    ed5cgs New Member

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    5
    below are image of the water heater, the exhaust pipe from the water heater is 3"

    Attached Files:

  4. Terry

    Terry Administrator Staff Member

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    14,992
    Location:
    Bothell, Washington
    That's not a direct vent, but a standard atmosphiric vented water heater and chimney.
    a small room like that should have ventialtion high and low for combustion air, and to prevent buildup of gas in the room. Sometimes thats a door with slats, and othertimes it's wall vents or grills.
  5. ed5cgs

    ed5cgs New Member

    Messages:
    5
    Terry,
    Thanks for the clarification.
    The side wall to the left of the water heater is an exterior wall. Could I convert the current venting to a direct vent through the exterior wall to the outside like this image to help reduce the heat build up in that room when the water heater is running?
    I'm located in California.

    Attached Files:

  6. Terry

    Terry Administrator Staff Member

    Messages:
    14,992
    Location:
    Bothell, Washington
    The Bradford White MI-5036FBN is a standard water heater. It would be ilegal to "try to convert" to a direct vent. If the gas company were to see someone do that, they shut off the gas to the home. I replaced something like that a few months ago.
  7. ed5cgs

    ed5cgs New Member

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    5
    Terry,
    Thanks for the info. So it sounds like the only way to remove the heat generated from the water heater is temperature controlled exhaust fan system?
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    New England
    Whatever you do, keep in mind that changing the interior pressure of the room can cause the WH to backdraft - IOW, you can't blow lots of air out unless you make provisions to let the same amount in easily, otherwise, you can create an unsafe situation, and likely disrupt the operation of the WH. If there's a next time, consider one of the closed-combustion WH's...these draw their own combustion air in from outside, and exhaust often through a concentric pipe, and some of them are efficient enough so that they can use PVC pipe rather than something like SS, which can handle the heat and corrosiveness of those that are less efficient if any of the exhaust condenses. Code requires a certain free grill (opening) per 1KBTU of burner. That should all be covered in the installation manual, which if you do not have it, can usually be found at the manufacturer's website. It's either that, or have a room volume big enough (even then, the 'standard' leakiness of the room may or may not be enough). It's more strict when it is in something like a closet, or smaller room.
  9. ed5cgs

    ed5cgs New Member

    Messages:
    5
    Thanks
    I just checked with Bradford White and they specify 2 in^2 / KBTU of vent area per grill high and low if your exchanging air internally or 1 in^2 of area if your exchanging from outside. 40,000 BTUs = 80 or 40 in^2. So a 10 x 10 vent should be good. Would a larger vent be better?

    So I guess today's water heaters really need that exchange of air in that room compared to a water heater that was 20+ years?
  10. Dana

    Dana In the trades

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    The burners on current model atmospheric drafted HW heaters aren't any bigger than they were 20 years ago- they needed it then, and they need it now. The combustion physics don't really change.

    As the IRC building codes specify ever tighter buildings many combustion appliances will simply have to be direct-vented (with piped-in combustion air) or at least power vented to avoid backdraft issues. But for now you're kind of on-your own with atmospheric drafted units for verifying that it won't backdraft when say, the clothes dryer & bath exhuast & kitchen hood are all depressurizing the house. (I personally will never again install an atmospheric drafted gas burner in my house, or a wood-burner that doesn't have a nominally air-tight piped in combustion air supply. YMMV.)
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    21,984
    Location:
    New England
    Today's houses tend to be built tighter than older ones...IOW, the older ones often had enough air leaks in them to allow the burner to function without issues. If that is true of your house, first, it probably would not meet current building codes, and second, you'd be wasting a lot of energy. The down side of this is, if you do use combustion devices that aren't sealed/closed (drawing their own combustion air from outside), if you do not properly account for it, you can have performance issues and may end up polluting your own air.
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