Delta shower cartridge -- no hot water

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Seattle, Feb 3, 2014.

  1. Seattle

    Seattle New Member

    Messages:
    12
    Location:
    Seattle, WA
    I installed a new shower in the upstairs bathroom. The cartridge is a Delta RP46074 for a Delta MultiChoice valve. When I turned on both hot/cold supply lines, there was plenty of cold pressure at the shower head but only a trickle of hot water.

    I then shut off the supply lines, removed the cartridge, turned on just the hot supply and there seemed to be plenty of hot water flowing through the body where the cartridge fits.

    I thought it might be the anti-scald hot water rotational limit stop on the cartridge so moved that to the maximum hot setting. That resulted in no hot water flowing through the valve. I then moved it to the minimum hot water setting and still no hot water. I'm still only getting cold water at the shower head.

    Thought it was a bad cartridge so bought a new one today and have the same problem----plenty of cold pressure but no hot pressure.

    I have this exact same cartridge on the downstairs shower and the pressure on both hot/cold is fine.

    Any ideas?
    Last edited: Feb 3, 2014
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,267
    Location:
    Cave Creek, Arizona
    No, because what you are describing is "illogical" and therefore something unique to your installation, meaning that we would have to be there to do our own testing and evaluation. However, because of the 'pressure balancing' unit in the cartridge, if there were no hot water TO the cartridge, it would also shut off the cold water.
  3. Seattle

    Seattle New Member

    Messages:
    12
    Location:
    Seattle, WA
    I sawed off the anti-scald ring to eliminate that from the equation. Installed the cartridge again, turned on hot water supply. Again, no hot pressure at all. Turned on the cold and again, cold water pressure was fine. Turned the hot supply on again and suddenly, I have hot water pressure (with or without the cold supply on).

    So, for those that stumble upon this posting with the same problem, I have no answer as to what the problem was or what fixed it. I doubt the anti-scald limit was the problem as removing it didn't resolve the issue immediately. Maybe it was a vacuum lock or something.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,267
    Location:
    Cave Creek, Arizona
    quote; Maybe it was a vacuum lock or something.

    In that case you discovered a new law of physics, namely, how to create a "vacuum or something" in a pressurized system.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,325
    Location:
    New England
    The pressure balance spool valve may have been lodged to one end and all of the bumping cutting, etc., dislodged it. On many designs, though, it shuts both supplies down, not just one. Could have been some crud that eventually got flushed out.
  6. Seattle

    Seattle New Member

    Messages:
    12
    Location:
    Seattle, WA
    Thanks jadnashua for the helpful reply. I'll bet your theory is correct.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,267
    Location:
    Cave Creek, Arizona
    IT is a "good" theory, (a stuck spool WILL shut down or restrict one side or the other), but probably not valid since you said you replaced the cartridge, which contains the spool, and it would be stretch to believe that you could get TWO bad ones, much less both of them bad the same way.
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