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Thread: Water Pressure too High

  1. #1
    DIY Junior Member
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    Default Water Pressure too High

    I have banging in my pipes when I turn off the faucets real fast but not when I turn them of slowly. The water pressure valve reads 80psi and I live in a condo. Early this year, I had a new electric water heater put in and it seemed to have started after that. Is the water pressure to high? I read it should be between 45 and 60 psi. I don't seem to get alot of pressure even with 80 psi. Can anybody give me some advice. Thanks

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    Retired Defense Industry Engineer jadnashua's Avatar
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    80psi is considered the maximum that should be available in a residential unit...more and you should have a PRV.

    If the pipes aren't anchored well, the intertia of the water stopping fast when you close the valve can cause the pipe to move and hit things (like the wall after making a 90-degree bend). Good practice should have anchored the pipes, but as a retrofit, you can add some hammer arresters near those valves that have that problem (it needs to be close to the offending valve to work). You'd likely have to tear apart a lot more to anchor the pipe, and that wouldn't do anything to poorly routed ones.

    Sioux Chief and Oatley make various versions and are the better known brands. Some can be installed by screwing them on, others require cutting pipes and inserting them. What you don't want is just a simple pipe stub...these quickly get their air absorbed into the water and no longer perform their normal function.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the Trades Gary Swart's Avatar
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    Chances are you are confusing flow and pressure. Pressure can only be measured with a pressure gauge. Volume or flow can be affected by constricted pipes, partly closed valve, debris that is plugging the pipe. In all of these cases, the pressure might read in the acceptable range.

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    Forum Admin, Expert Plumber Terry's Avatar
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    The new water heater may have "check's in the connections.
    These are meant as "heat traps" to prevent hot water just wondering around and not staying in the tank until called for.

    If that is the case, you may need to invest in some hammer arrestors.
    Good locations would be at the dishwasher, ice maker and the washer.

    If you don't have much pressure at the faucet, make sure the shutoff is opened all the way,
    Sometimes a barely open shutoff will have a loose rubber washer that flips around causing havoc.

  5. #5
    DIY Senior Member Runs with bison's Avatar
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    How well does a thermal expansion tank do as a hammer arrestor? Most of the hammer arrestors appear to be prone to waterlogging unless they have an actual diaphragm separating the phases. An expansion tank should absorb some surges due to the wide surface and bladder, but the neck to it is not oversized so I could see that literally bottlenecking the surge suppression capability.

    After installing my new Toto's I now have a thermal expansion problem...it appears that the old toilets must have been allowing leak by at the fill valves at around 100-110 psig according to my test gauge. I wondered why I was not seeing more thermal expansion, now I know. The Toto's are not leaking by as pressure rises, so the T&P relief valve is dribbling at about 155-160 psig after showers and the test gauge is confirming the pressure spike. I am preparing to replace the failing PRV and install a thermal expansion tank too.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
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    You need the arrestor as close to the errant valve as possible...the column of moving water needs someplace to go. A decent arrestor uses either a piston that is sealed with air on one side or a bladder. Do not confuse these engineered arrestors with a simple T and a length of pipe. They are not the same thing, although the T will work for a while, not anywhere near as long as an engineered version.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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