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  1. #1
    Join Date
    Jan 2012
    Posts
    2

    Default Lack of hot water in newly renovated shower

    We recently had our hall bath renovated. It's been almost 8 months and we cannot get hot water in the shower. We replaced Moen faucet cartridge,replaced Moen balancing spool, bypassed piping leading to shower, all to no avail. All the other faucets in the entire home work fine.Oil fired boiler with tankless domestic hot water coil. Home is 27 years old. Pulling the handle to turn on water brings us very hot water turning warm then just warm but not enough to shower within 15 seconds after turning on. What could be the problem and how can it be solved. Original contractor said recommended acid washing domestic hot water coils, but it doesn't make sense since there is adequate amount of hot water in the rest of the house. Also the water quality in our area is very good, soft and no other related problems from neighbors. Looking for any advice.

    Thank you

  2. #2
    Join Date
    Nov 2011
    Location
    boston,ma
    Posts
    114

    Default Re: Lack of hot water in newly renovated shower

    I would bet it is in the valve assembly, if you get some hot water and then it goes away. Try to remove the shower head and run the hot water on full and see if the hot water stays hot. If you have a new tankless on demand then the flow might not be enough to trigger the burner, if you have a nearby sink turn on the hot water and see if the shower water turns hot if this is the case you need to add a low flow trigger to the tankless unit they are suppossed to turn on the burner at .25 gals a minute according to a friend who is a plumber. Good Luck!

  3. #3
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,213

    Default Re: Lack of hot water in newly renovated shower

    I believe he said he had a tank less coil not a tank less on demand. The coil may be your problem and the reason it's not apparent in the sinks is because the sinks have a lower flow rate. To check to see if the coil is not producing the hot water required for the shower. Turn on the shower and feel the hot water line exiting the coil to see if it is in fact cooling down at that point. Tank less coils are a very inefficient and expensive way make hot water.

    John

  4. #4
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,598

    Default Re: Lack of hot water in newly renovated shower

    When you said you bypassed the lines to the shower head, what did you replace them with?

  5. #5
    Join Date
    Nov 2011
    Location
    boston,ma
    Posts
    114

    Default Re: Lack of hot water in newly renovated shower

    Oh yes I see tankless coil, I had this same set up in my steam boiler, coil on the bottom,It was already leaking internaly when I bought the house, lasted 1 year and had to switch to just a new tank type water heater. They had an electric tank backup to run in the summer when boiler was idle. The water was always way to hot, I never had problem with being too cold, but it was very expensive to run that unit. I could see this coil having issues, How is the water in the rest of the house? If your other bath shower is working fine, then it is pretty much isolated to the new bath, maybe there is not enough hot water at the balancing spool, a pressure differential could cause this if the hot line is restricted somewhere, the only time I had a similar situation is when a apprentice plumber on a job I was doing put in a generic shower/tub diverter bacwards and the cold/ hot was reversed and the shower was using the tub output, and the shower outlet was capped because it was a shower stall. It took them a week to figure this out, I guess the cartridge could be reveresed on this model. I would check the flow and see if its equal, maybe you can backflush the lines, there could be a peice of solder or sediment stuck somewhere, this is all I can think of at this moment. Good Luck!

  6. #6
    Join Date
    Jan 2012
    Posts
    2

    Default Re: Lack of hot water in newly renovated shower

    Quote Originally Posted by dj1 View Post
    When you said you bypassed the lines to the shower head, what did you replace them with?
    we replaced them with copper tubing.

  7. #7
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,213

    Default Re: Lack of hot water in newly renovated shower

    What were the lines before you replaced them? Were they galvanized? If you have galvanized piping still in service that could very well be your problem.

    John

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