Gas water heater help

Discussion in 'The Garage' started by MaineScoot, Dec 16, 2012.

  1. BigDogAdventures

    BigDogAdventures Fart Letter

    Joined:
    Sep 13, 2003
    Oddometer:
    5,148
    Location:
    Mt. Vernon, Illinois
    As a lifelong state licensed plumber that spent his whole life installing and repairing steam and hot water systems I can tell you professionally that a water heater is the very most in-efficient way to heat a building using your radiant heating system. The efficiency rating is a small percent of what a boiler is made for that purpose. But water heaters are cheaper than boilers------just so you know.


    BigDog
    #21
  2. MaineScoot

    MaineScoot Been here awhile

    Joined:
    Jan 22, 2011
    Oddometer:
    565
    Location:
    Portland
    Thanks for all these ideas. The annoying thing is if I go downstairs right now and turn on power to the unit it will start right up and run fine until everything is up to temp. It's only the next time it tries to turn on that it wont fire up. It just tries over and over.

    Bigdog, I know that this water heater isn't as efficient as a real boiler. I'm just heating a 450 sf basement shop to about 50 degrees. If I have a big project going I might turn it up to 55 for a couple of days. I just didn't think I needed to spend 3 or 4 thousand dollars for a real boiler for this application. The whole thing has worked fine for over a decade.

    So what I've been doing the last few weeks is to just turn it on and let the floor/room heat up then turn it off when I hear it failing to light. I will find time soon to go over the manual.
    #22
  3. MaineScoot

    MaineScoot Been here awhile

    Joined:
    Jan 22, 2011
    Oddometer:
    565
    Location:
    Portland
    Update: I limped through last winter just turning the water heater on once a week or so to warm up the slab. It would run for 6 or 8 hours then go into failure mode. So in October I called in a pro, the heating company that services our oil burner sent over their gas guy and he checked out the heater. He diagnosed the problem as a bad pressure switch. He said he would order one and be back in a week or so to put it in. A few weeks went by and no word. I called and they said they were having trouble finding the switch. And that's how it's gone all winter. They kept saying they could find it and they'd let me know. Until 2 weeks ago. That's when they told me they couldn't find the switch and I was on my own.
    So I emailed the guy at State that sent me the service manual last winter and he said sorry, State won't support it but try hotwater.com. So I contacted them and they said sure, no problem, we'll send it right out.
    So I put it in last night and guess what? It's still doing the same thing. Doh! I'm back to square one.
    Rereading this thread, and knowing it wasn't the pressure switch it must be the flame sensor. Right?
    #23
  4. Walterxr650l

    Walterxr650l Long timer

    Joined:
    Mar 3, 2006
    Oddometer:
    1,325
    Location:
    Donald, Oregon
    It could be, but it could also be a bad connection in the control and/or safety circuits, a bad gas control valve, or a bad control circuit board, or ??? You really need to read your service manual, and figure out the firing sequence. Then use a meter and check for the proper voltage at each component in the control and safety circuits, in sequence. Make sure all wire connections are clean and tight. It doesn't take much corrosion to block 24 Volt control voltage. It takes even less if it is a millivolt system. Or you can keep guessing and throwing parts at it till you get lucky and get the right one.

    Walter
    #24
  5. DUNDERHEAD

    DUNDERHEAD Been here awhile

    Joined:
    Jan 6, 2010
    Oddometer:
    193
    Location:
    CT
    MaineScoot, call the propane company and have them come out and change the outside regulator. I was having the same puzzling experience with my radiant heating system. It would start up and run for a while - shut off - start and run - shut off. Everything checked out fine, but it just would not run consistently. I did everything short of jackhammering up the slab to change the Pex to try and fix the problem. Two different plumbers couldn't figure out what was wrong.
    Finally I called the propane company and they said I probably have water in the gas. They sent a service tech who removed the regulator, took it apart and showed me the inside which was frozen solid with ice. During the day as the sun warmed the regulator, the inside thawed and would allow enough gas to pass and fire the wall mount boiler. Later as the temperature fell, it would freeze and block the gas flow. The service tech said the propane delivery drivers are supposed to manually add methanol ( ? ) at each truck fill during the winter months to prevent freeze ups. But some times they forget.
    New propane company and all is well !
    #25
  6. MaineScoot

    MaineScoot Been here awhile

    Joined:
    Jan 22, 2011
    Oddometer:
    565
    Location:
    Portland
    Thanks, Walter. I'll have time to do that Saturday.

    DH, it burns Natural Gas not Propane so I don't think it's a water issue. Plus the kitchen stove and the Rinnai in the apt over the garage are both burning fine.

    The most frustrating thing is if I go downstairs right now and turn it on it will run fine until morning.
    #26
  7. Beezer

    Beezer Long timer

    Joined:
    Oct 26, 2004
    Oddometer:
    6,004
    Location:
    Anchorage, formerly Spenard (hub of the universe)
  8. MaineScoot

    MaineScoot Been here awhile

    Joined:
    Jan 22, 2011
    Oddometer:
    565
    Location:
    Portland
    So here I am 2 years later and I never sorted out my heater issues. I thought I'd try one more time here before bringing in a pro again. Remember, that didn't go well last time. So here are a couple of pages from the manual:

    [​IMG]


    [​IMG]


    I've replaced the pressure switch. It still does the same thing. I took a video last year, I'll try to find it. I feel like this thing is so simple that I should be able to figure it out.
    #28
  9. 9Dave

    9Dave Bazinga!

    Joined:
    Aug 4, 2005
    Oddometer:
    13,526
    Location:
    Central Ohio
    I saw your previous post about the pressure switch. It sounded like the problem.

    When mine went bad on my furnace, a generic replacement from the local supply house fixed me up, and was a lot cheaper than the OEM.

    If it were me, I'd start it from cold and carefully note the start cycle sequencing and what each component is doing. Then I'd lower the temp to let it shut off, turn the temp back up so it will try to restart, and note what doesn't happen correctly.

    I'd think the cycle would be something like the the blower comes on and closes the pressure switch (you should be able to confirm the pressure switch closed with an ohm meter, or a test light) Then you should hear a click as the gas valve opens, and you should hear gas flowing. Then the main flame should light off the pilot. Or something like that.

    But something is obviously not happening when it tries to relight that successfully happens when it lit the first time.
    #29
  10. trailer Rails

    trailer Rails Long timer

    Joined:
    Jun 13, 2008
    Oddometer:
    5,039
    Location:
    Pittsburgh PA
    Earlier in this thread, someone mentioned the offices on the draft inducer fan getting clogged. Check them again, they are tiny and clog easily.

    Post a pic of the pressure switch its self. When the rubber tube is removed, is there a restrictior piece in the nipple on the switch?
    #30
  11. showkey

    showkey Long timer

    Joined:
    Jun 25, 2007
    Oddometer:
    2,004
    Location:
    Wausau
    My pressure switch hose on my furnace had a slit in the middle........intermittent no burner............. it coded for switch on the control board. Got to say it was one poor quality hose compared to automotive stuff.
    #31
  12. KeithinSC

    KeithinSC Long timer

    Joined:
    Oct 18, 2009
    Oddometer:
    1,713
    Location:
    Sandhills of SC
    This is good advice. The vacuum switches are calibrated with a small orifice in the nipple. sort of like jets on a barb. If it is the wrong switch (orifice) the system will not work. The orifices can fall out or get lost when swapping switches. Usually a tiny piece of colored plastic with a hole thru it.
    #32
  13. rapidoxidationman

    rapidoxidationman Easily trainable

    Joined:
    Apr 18, 2006
    Oddometer:
    9,123
    Location:
    The Teton Rockies
    is there a sediment trap on the NG line coming into the water heater gas control?
    #33