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  1. #1
    Join Date
    Jan 2013
    Posts
    6

    Default Volume or Pressure?

    My main tub has really low flow. So low that the diverter hardly stays up and the water doesn't want to transfer to the shower head.

    I thought it was the valve so I replaced the main shower valve, spout, and shower head. It looks great but there is no difference.

    I called the city to check my pressure. According to the guy who came out, the pressure at the water tower (which I can see from my house) is 60psi. He measured 58 at my meter. He measured about 55 or 56 at the shower head. So it doesn't seem to be a pressure issue.

    The main line is a 1" copper pipe. This is reduced to a 3/4" for the middle part of the run, but all feeds off that 3/4" pipe are 1/2" lines. This is true for every faucet, appliance, the tub and shower in the master bath.

    What are we missing here? Do I need to replace all the 1/2" with 3/4"?

  2. #2
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,904

    Default Re: Volume or Pressure?

    No, you don't need to replace all the 1/2" lines; that is a plenty big enough size. I would suspect another restriction in the line, such as a shutoff valve somewhere in the lines.

    No matter what the size of the pipe, you'll always get that same STATIC pressure reading if there is no water flowing anywhere in the house. A more meaningful test is to check the pressure at the showerhead while you run various faucets around the house (remove aerators first). That can help pinpoint the problem. For example, if the washing machine causes the pressure to drop but the kitchen faucet doesn't, that can indicate that both the shower and the washing machine are downstream of the blockage but the kitchen faucet is upstream.

    Do you have a pressure regulator? Sometimes those can cause this issue, but usually for the whole house.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  3. #3
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,257

    Default Re: Volume or Pressure?

    What type pipe do you have? If it's galvanized it may be time to replace it. Over time galvanized lines close done with build up inside the line.
    John

  4. #4
    Join Date
    Mar 2013
    Location
    WI
    Posts
    112

    Default Re: Volume or Pressure?

    Agree,they said the main line is copper,but are all the runs copper,or just the 1'"?

  5. #5
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    7,760

    Default Re: Volume or Pressure?

    It's not very uncommon to see copper main line and galvanized wall pipes, especially in older homes.

    So what to do? you need access to the supply pipes to the tub - cut the drywall behind the tub. When you see what you have you can determine what to do next.

  6. #6
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,904

    Default Re: Volume or Pressure?

    With galvanized pipe, blockages are most common at fittings. This is because there is exposed, ungalvanized steel in the fitting's threads and the cut end of the pipe. This exposed steel will "grow" iron oxide (rust) deposits until the pipe literally closes off. Sometimes as a stopgap measure you can turn on the water and take a hammer and bang on the fittings and it will knock stuff loose, but that's only a temporary fix and doesn't address the real problem which is that galvanized steel pipes are not the best material for water supply.

    As for the ideal materials, either copper or PEX (cross-linked polyethylene). Certain water conditions are problematic with copper. I can't recommend CPVC because it gets brittle over time and can fail dramatically when frozen.
    Last edited by Fencepost; 10-24-2013 at 12:22 PM.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

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