Water Pressure issues

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by wak, Jul 15, 2010.

  1. wak

    wak New Member

    Messages:
    5
    Location:
    Nashville
    I had to replace my water heater recently and since the new one was installed the following has happened:
    • kept getting water from the T&P valve
    • water pressure in the house seemed to be higher
    • the installer replaced the T&P valve
    • continued to get water from the T&P
    • the installer reduced the water pressure via regulator
    • water in house has big spike of pressure when turning on
    • T&P situation worsens, I am emptying a 3 gallon bucket several times a day now
    • a toilet supply line has busted

    Here is what I know about my situation:
    • we have very high water pressure in our neighborhood (spiking to at least 165psi)
    • the issues described above did not exist before the new water heater
    • the pressure regulator for the house is in the garage by the water heater - I don't know if the installer changed the way it was hooked up, but I know he did work on those pipes

    What I am trying to figure out:
    • Are my issues coincidence or are they related to the water heater installation?
    • If they are related, is the installer responsible?
    • Is there a way to get Metro Water to reduce the water pressure into the sub-division

    Any advice would be greatly appreciated. Thank you.
  2. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,398
    Location:
    Yakima WA
    You need a thermal expansion tank installed between the pressure regulator (PRV) and the water heater. This is what is happening. When the water heats in the tank, it expands. The PRV and perhaps even the water meter, has a check valve to prevent the expansion from being absorbed by the city water main. The pressure in the tank rises and opens the T/P which is functioning properly. The PRV should be installed between the main shut off valve and where it tees off to go to the water heater and the rests of the house. The air pressure in the expansion tank and the PRV setting should match.
  3. wak

    wak New Member

    Messages:
    5
    Location:
    Nashville
    Oops, I forgot to mention that I did not have a thermal expansion tank installed on my old water heater, but I do now. Any other ideas?

    Thanks so much for the reply!

    Ian
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,438
    Location:
    Bothell, Washington
    165 PSI is smoking high!

    Have any other plumbers out there seen street pressure that high?
    I've seen 120 PSI.
    I would make sure the PRV in your home is working. Sometimes they need a rebuild or replacement after ten years.

    Most plumbing codes restrict house pressure to 80 PSI, and a better setting would be around 50-60.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,344
    Location:
    New England
    Get a pressure gauge, if you don't have one, and see what's happening. Also, check the specs on the PRV. Some don't like more than 'x' pressure differential from inlet to outlet. So, you may need two of them in series, each dropping the pressure some. Make sure that the expansion tank is properly filled...it should be approximately the 'normal' working pressure. You can't just measure the pressure on the Schrader valve until you turn off the water, and relieve the water pressure; otherwise, it will just read the water pressure (a backup check on the water pressure gauge for accuracy).
  6. wak

    wak New Member

    Messages:
    5
    Location:
    Nashville
    I get the 165psi figure from a pressure gauge a neighbor bought. We went around the neighborhood testing various homes. The gauge maxes out at 165 and the spigot pinned the gauge.

    Unfortunately, the water pressure killed my front spigot years ago, so I have nothing to attach a gauge to for reading the raw pressure level.

    I'll check the PRV, i think it might have been replaced with the installation, so if this one is not rated as well as the last one...?
  7. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Around here I'll see 130 regularily, sometimes a bit higher. But neve 165 psi +.... that's REALLY high for a static pressure.

    To the OP > If your pressure is that high there is only 1 thing to blame and it's a failed PRV.
  8. wak

    wak New Member

    Messages:
    5
    Location:
    Nashville
    Just talked to metro water, and they tell me the official number is 180psi for our sub-division. I checked the PRV and it is rated 25-75 with max pressure of 300psi. Sound like I'm asking too much from this PRV?
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,344
    Location:
    New England
    You can attach the pressure gauge at the drain of the WH, or the washing machine supply, or with adapters, anywhere. If you ride a bike, your pressure gauge might go high enough, and you can check the pressure at your expansion tank.

    As long as the PRV is working, and rated for your conditions, it should be able to maintain the desired pressure. If it can't it either needs to be rebuilt, or replaced. If the expansion tank is shot, it will fill with water, and you could have the same symptoms, so it might not be the PRV. Verify the expansion tank is primarly full of air, not water (you should only get air out of the Schrader valve (like a tire valve) used to check and inflate the tank). If you get water out of the expansion tank when checking the pressure, it is shot, and needs replacing.
  10. shacko

    shacko Master Plumber-Gas Fitter

    Messages:
    561
    Location:
    Rosedale, Md
    I did a job years ago where all the pressure in a residential area was 150lbs.
  11. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,398
    Location:
    Yakima WA
    We could toss out ideas and suggestions all day, but what you must do first is test the pressure. Buy your own gauge at any hardware store. They are cheap (less than $15) You have to reduce the incoming pressure. That much pressure will continue to damage your toilets, washer, and dishwasher. You just flat don't need or want that much pressure. Mine is reduced to 50 psi, but a bit more wouldn't hurt. As previously noted, you need to verify the thermal expansion tank is still working. They do wear out and become waterlogged and no longer work. Once you get the pressure under control and an operable expansion tank, your troubles will be over.
  12. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    I for one wonder why the installer walked away leaving the T&P dripping...
    I don't walk away from problems like that without telling you what you need to pull out of your wallet to have me fix the problem.
    It sounds like you need a different plumber.
  13. wak

    wak New Member

    Messages:
    5
    Location:
    Nashville
    Thank you guys for the help. I got a second opinion from another plumber. I am building up at least 150lbs pressure in the tank. We think now that maybe the PRV is acting as a check valve, since there is 180lbs of pressure behind it from the city. Considering moving the PRV further from the tank.
  14. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Pressure in a static water system will be the same through-out the entire system. So where you place the PRV has nothing to do with how it will effect your pressure. Not only that but the incoming pressure into the PRV has nothing to do with how it operates seeing how they are normally-open type valves.

    What you need to do is verify the static house pressure with the hotwater tank COLD(ish) so that you can measure to see if the PRV is working. Then what you need to do is install a pressure tank between your HWT and the PRV so there is no isolation valves between the two.

    If it is simply thermal expansion of the water in the tank causing the spike in pressure then you'll find the static water pressure in your house with the tank cold to be less than 75 psi (as most prvs for residential max out at 75 psi).
  15. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    If you have 180 psi in the street the internal bypass is doing nothing...
    How could you think 150 could bypass back into 180?
  16. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,344
    Location:
    New England
    The new WH probably just exposed some pre-existing problems. Especially if the new WH is bigger than the old one, or you have the thermostat set higher, there will be more expansion and thus a higher pressure built up. Without an expansion tank installed, you are wasting time trying to fix something that may not be broken except for the lack of an expansion tank.

    So, install a new expansion tank, then see if the PRV is working. If not, repair or replace it. Then, you should have a system that can work. Until then, you're wasting your time. You can easily build up enough pressure from the WH heating water to create enough to cause the T&P valve to dump.

    Turn the WH off. Open a faucet to let some water run. Close it, then measure your pressure. If it is okay and stable, the PRV is working. If you run hot enough to cool off the tank. Then shut the valve, and turn the WH back on...monitor the pressure. You will see it rise. You really need an expansion tank.
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