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prstlk's avatar
prstlk
Explorer
Jun 10, 2019

suburban water heater flow stopage

07 36 ft 5th wheel with a suburban AC/LP hot water heater.
Just today while running hot water for dishes and the flow just stopped not only at the sink but bathroom sink shower and outdoor shower. I had cleaned the outdoor water hookup area and thought I may bumped the bypass valve. Checks out okay. Started working a again and while I was rinsing the dishes it quit again I heard a thunk from the area behind the pantry where the heater lives. I checked the reset buttons on the heater nothing there either,
Any ideas as what would interrupt the hot water flow but not the cold?

Thanks to all in advance
Jim

9 Replies

  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jun 12, 2019
    Bobbo wrote:
    Old-Biscuit wrote:
    Opening T&P can cause air pocket to be expelled vs being established

    If you depressurize the water system and open the pressure relief valve, it will also re-establish the air pocket.


    YES.........
    That is How you can re-establish a lost air pocket
    Opening T&P with NO pressure/flow

    Opening it WITH water turned on can displace the air pocket because the water will churn inside the WH Tank and carry the air out thru T&P vs flowing naturally thru hot out dip tube to an open faucet
  • Bobbo's avatar
    Bobbo
    Explorer III
    Jun 12, 2019
    Old-Biscuit wrote:
    Opening T&P can cause air pocket to be expelled vs being established

    If you depressurize the water system and open the pressure relief valve, it will also re-establish the air pocket.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jun 12, 2019
    prstlk wrote:
    Thanks to all who answered. It was indeed the check valve at the top of the water heater. $10.00 part.

    I would recommend everyone have a 1" deep well socket on hand in case you need to remove the old one.

    Make sure that you open the pressure relief valve on the water heater so it can fill with water after the replacement.

    Also recommend that you study up on being a contortionist because you have to crawl up into the belly of the unit to be able to get to the check valve (at least that's what I had to do).


    Glad you got it working!
    No need to open T&P Relief Valve when refilling.
    Turn on water supply and then open nearest faucet hotside.
    This will allow cold water to flow into WH Tank, displace the air in system AND establish the 'air pocket' at top of tank,
    Air pocket helps control pressure increases when heating water as it will SWELL when heated so w/o air pocket pressure can increase and cause the T&P Relief Valve to 'weep'

    Opening T&P can cause air pocket to be expelled vs being established
  • prstlk's avatar
    prstlk
    Explorer
    Jun 12, 2019
    Thanks to all who answered. It was indeed the check valve at the top of the water heater. $10.00 part.

    I would recommend everyone have a 1" deep well socket on hand in case you need to remove the old one.

    Make sure that you open the pressure relief valve on the water heater so it can fill with water after the replacement.

    Also recommend that you study up on being a contortionist because you have to crawl up into the belly of the unit to be able to get to the check valve (at least that's what I had to do).
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jun 11, 2019
    Top fitting is HOT out
    Fitting screwed into the HOT Out will be the check valve

    It is clogging up with scale/crud/minerals

  • DFord's avatar
    DFord
    Explorer
    Jun 11, 2019
    At the hot water outlet of your water heater, I'll bet there's a check valve like this one:

    It's pretty small and not very conspicuous but if you've got a single handle water heater bypass, you've got one of these valves. The disk that prevents the backflow of water into the heater is plastic and held in place with a small rivet. That rivet pulls through the plastic and plugs up the outlet to the heater.

    Be careful selecting a replacement. I was able to find one with a brass disk instead of plastic. It was the same brand but I'm not sure if it had the same part number.
  • prstlk's avatar
    prstlk
    Explorer
    Jun 11, 2019
    dougrainer wrote:
    The Hot water exit fitting probably has a check valve and that valve may have mineral deposits. How often do you replace the Anode rod? Doug


    Doug,

    Can you enlighten me on what the exit fitting looks like? The anode was checked in April and it was fine.
  • Roger10378's avatar
    Roger10378
    Explorer II
    Jun 10, 2019
    Even more likely is that the check valve has failed. Most are cheap plastic and fall apart. If you can find a brass check valve it will be worth the extra cost.
  • dougrainer's avatar
    dougrainer
    Nomad
    Jun 10, 2019
    The Hot water exit fitting probably has a check valve and that valve may have mineral deposits. How often do you replace the Anode rod? Doug

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