1-of-2 water heaters is busted, can I still use the other?

Discussion in 'Water Heaters and Softeners' started by BrianFtx, Nov 18, 2018.

Help Support Plumbing Forums by donating:

  1. Nov 18, 2018 #1

    BrianFtx

    BrianFtx

    BrianFtx

    Member

    Joined:
    Nov 18, 2018
    Messages:
    6
    Likes Received:
    0
    Location:
    Texas
    [​IMG]
    BrianFtxNew Member
    Hi all,

    DIY guy here. Two Gas water heaters installed right next to each other at same height (one in a closet, the other just outside the closet).

    One was replaced this past summer (New), the other is 15yo old (Old) started leaking last night, then the entire drain valve completely broke off the tank. I'm not sure how they are plumbed, and not sure what is safe to do here. The New heater has a shut off on only one line (I'm assuming in inlet line). The Old heater has shut off valves on both lines.

    Currently I have turned off the gas to both heaters, and both lines on the Old heater are shut off. The Old tank is empty. Both lines on the New tank are open. With this set up, I still get water coming from hot water tap, it's just no longer hot.

    My question is this: can I restore gas/heat to the New heater and have hot water supply for the house while the Old heater is completely shut off & turned off?

    My thought is that, if they were plumbed in series, then shutting both valves on the Old heater as I have done would stop water from coming out of tap when hot side tap turned on. Unless the New tank is the second tank in the series and it is somehow drawing water from the new tank outlet despite the fact that there is no new supply coming into it. Seems like shutting both valves on either tank would stop hot water from making it to a tap's hot side. So since I have water (even though it is cool water since all gas is off) coming out when I open hot tap, is that proof that these are plumbed in parallel??

    This leads me to believe they are parallel, which hopefully means I can relight pilot and restore gas/heat to the new heater while the old heater is completely shut off, allowing me to have hot water until the Old tank is replaced.

    Does this make sense?

    Thanks for any thoughts/advice!!
     
  2. Nov 18, 2018 #2

    Geofd

    Geofd

    Geofd

    Professional Professional

    Joined:
    Jan 20, 2018
    Messages:
    713
    Likes Received:
    109
    Location:
    Boston, Massachusetts
    shut off the gas to the old heater shut off the hot and cold....CAP OFF THE GAS FLU TO THE OLD ONE....then see what happens while running just one
     
  3. Nov 18, 2018 #3

    BrianFtx

    BrianFtx

    BrianFtx

    Member

    Joined:
    Nov 18, 2018
    Messages:
    6
    Likes Received:
    0
    Location:
    Texas
    How do I go about capping off gas flu to the old one??
     
  4. Nov 18, 2018 #4

    Geofd

    Geofd

    Geofd

    Professional Professional

    Joined:
    Jan 20, 2018
    Messages:
    713
    Likes Received:
    109
    Location:
    Boston, Massachusetts
    are you going to replace the old one???? if so just remove the flu from the water heater get the the appropriate cap size...screw it to the exsisting flu if you not going to replace it go back to the branch fitting on the flu and cap there and remove gas and water piping
     
  5. Nov 18, 2018 #5

    BrianFtx

    BrianFtx

    BrianFtx

    Member

    Joined:
    Nov 18, 2018
    Messages:
    6
    Likes Received:
    0
    Location:
    Texas
    ...and why do I cap it off if it's not on?
     
  6. Nov 18, 2018 #6

    BrianFtx

    BrianFtx

    BrianFtx

    Member

    Joined:
    Nov 18, 2018
    Messages:
    6
    Likes Received:
    0
    Location:
    Texas
    Yes going to replace in a week
     
  7. Nov 18, 2018 #7

    Geofd

    Geofd

    Geofd

    Professional Professional

    Joined:
    Jan 20, 2018
    Messages:
    713
    Likes Received:
    109
    Location:
    Boston, Massachusetts
    because its still connected to an active chimney or flu..... if you are asking these questions you should leave this up to a lic/insured plumber.....
    that's the best advice you should take today....don't fool around with gas!!!!!!!!!! shutting off water valves is one thing.....my fault for giving you advice.....call a plumber
     
    SHEPLMBR likes this.
  8. Nov 18, 2018 #8

    BrianFtx

    BrianFtx

    BrianFtx

    Member

    Joined:
    Nov 18, 2018
    Messages:
    6
    Likes Received:
    0
    Location:
    Texas
    Is capping the flu on the old one that is shut down necessary for safety?
    I'd like to have hot water for the next week, but not sure I can successfully cap this, and I don't want an unsafe scenario
     
  9. Nov 18, 2018 #9

    BrianFtx

    BrianFtx

    BrianFtx

    Member

    Joined:
    Nov 18, 2018
    Messages:
    6
    Likes Received:
    0
    Location:
    Texas
    Yep, that's my plan. Leaving gas off to both until a pro gets here
     
  10. Nov 18, 2018 #10

    Geofd

    Geofd

    Geofd

    Professional Professional

    Joined:
    Jan 20, 2018
    Messages:
    713
    Likes Received:
    109
    Location:
    Boston, Massachusetts
    PLEASE CALL A LIC/INSURED PLUMBER YES ITS A SAFTEY ISSUE DONT FOOL AROUND WITH GAS!!!!!!!!!!!!!!!!!
     
  11. Nov 18, 2018 #11

    Geofd

    Geofd

    Geofd

    Professional Professional

    Joined:
    Jan 20, 2018
    Messages:
    713
    Likes Received:
    109
    Location:
    Boston, Massachusetts
    you made the right call.....
     
    mike fiore likes this.
  12. Nov 19, 2018 #12

    ExtraMilePlumbing

    ExtraMilePlumbing

    ExtraMilePlumbing

    Well-Known Member

    Joined:
    Aug 21, 2014
    Messages:
    485
    Likes Received:
    81
    Location:
    ,
    I believe due to chance of a backdraft from either plugged vent or a power vented appliance pushion co2 down
     

Share This Page