Inline TPR valve???

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by CharlieG, Sep 30, 2004.

  1. CharlieG

    CharlieG New Member

    Messages:
    16
    Location:
    Seattle, WA
    A friend asked me to check an exterior "leaking pipe" extending from just above her foundation. It was a dripping 3/4 inch copper line directed downward and terminating just inches above a planting bed. Examination in the unfinished part of her basement revealed a connection to what appeared to be a standard TPR valve connected to the hot water line and situated about 20 feet from the water heater (which had its own properly installed and working TPR valve). The valve was at an intersection between two branches of the hot water line. One horizontal copper branch led into the finished portion of the basement, feeding the adjacent laundry room and the kitchen above. The other horizontal branch led into an old and fragile-looking galvanized pipe, feeding the basement's half bath. I opened and closed the valve several times to loosen any debris that may be preventing it from fully closing, but to no avail. My friend told me that when she bought the house several years ago, an inspector told her that the water pressure was very high. I suspect that the valve was installed at this intersection to additionally protect the fragile iron pipe branch from either the high incoming pressure or possible water hammer from the kitchen and laundry room appliances. If this is the case, should I simply install a pressure reducer valve on the main line from the street and eliminate the oddly placed TPR, or replace the TPR itself? I've assumed the TPR is faulty because the TPR on the water heater uphill from it is working properly and not leaking. I guess that also assumes that the odd TPR has the same pressure rating as the water heater's valve (I can't see the valve's tag because it is too close to the basement ceiling). Any help is appreciated.
    Last edited: Sep 30, 2004
  2. e-plumber

    e-plumber DIY Senior Member

    Messages:
    137
    Location:
    New York
    Temperature & Pressure Relief Valve

    [​IMG]
    Usually referred to as a "T & P".
    The valve that you described, if it is a T & P is serving only as a pressure relief valve in that location although there are pressure only relief valves but that installation appears to be a feeble attempt to allow excessive system pressure to drain outside the house instead of the T & P on the water heater discharging because of what appears to be high incoming water pressure.

    If the water pressure is above 80 P.S.I., a pressure regulating valve needs to be installed on the cold water main, a thermal expansion tank is generally installed on the cold water feed line to the water heater when a PRV is installed.

    The valve that is leaking should be removed from its' location.
  3. CharlieG

    CharlieG New Member

    Messages:
    16
    Location:
    Seattle, WA
    Pressure regulating valve

    Thanks, e-plumber.
    If I use a pressure regulating valve with a thermal expansion bypass feature, such as the Watts 25AUB, would it still be necessary to install a thermal expansion tank on the cold water feed line to the water heater?
  4. e-plumber

    e-plumber DIY Senior Member

    Messages:
    137
    Location:
    New York
    Pressure regulating valve

    You're Welcome.
    A thermal expansion tank will be needed if the incoming water main pressure is higher than what is being created within the system due to thermal expansion or one may be needed if there is a check valve on or near the water meter.
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Is the item at the WH a true TP, or could it be a Watts 210 temperature activated gs shut-off. If this were the case, then a separate pressure relief with discharge to the outside of the dwelling is required.
  6. CharlieG

    CharlieG New Member

    Messages:
    16
    Location:
    Seattle, WA
    T & P, etc.

    Jimbo,
    I don't live close to my friend and I just got a fast look at the water heater and quickly tested what seemed like a standard 150lb T & P attached to it in the usual manner. I'm not a plumber and don't know that I'd recognize a temp activated gas shutoff, but wouldn't it be tied in with the gas supply as well as the water?
    Sorry, but I'll have to continue this thread tomorrow since I have a commitment for which I'm already late.
    I hope you and E-plumber won't mind answering more questions tomorrow.
    Thanks, again.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Yes, the 210 has gas lines in and out. Also, it does not have the little test toggle lever. Instead,it has a red reset button. I only brought this up because it does come up and sometimes throws people for a loop.
  8. Terry

    Terry Administrator Staff Member

    Messages:
    14,994
    Location:
    Bothell, Washington
    In some areas, if the water heater T&P (150 PSI) can't be drained to the outside, they require a relief valve somewhere else on the system.

    Sometimes you will put in the 150 PSI T&P on the water heater and a 125 PSI relief on in a spot that will drain to the outside.
    The idea being that the pressure will relieve outside before the inside T&P on the heater opens up.

    In fact, the city of Bellevue WA for a long time only required the 125 PSI relief valve on the cold water line and none on the water heater.

    Needless to say we argued with the inspector over this one.
    Of course logic doesn't always win with an inspector. :(

    Now whenever the city finds this arrangement during an inspection, they ask the homeowner for a waiver.
  9. CharlieG

    CharlieG New Member

    Messages:
    16
    Location:
    Seattle, WA
    Thanks Terry, Jimbo, and e-plumber. I appreciate all your comments and recommendations.

    e-plumber,
    I am just a long time do-it-yourselfer and hope that my questions are appropriate. Regarding your last post, I'll check the meter for a check valve and test incoming pressure at the hose bib closest to the main shutoff. What is the best place/procedure for testing the in system pressure due to thermal expansion?

    Terry,
    If the second relief valve is due to a code situation as you described, wouldn't it be installed on the cold water supply uphill from the water heater instead of on the downhill hot water line? The house is in the Seward Park section of Seattle, so you may be familiar with applicable codes.
    Alternatively, if e-plumber is correct in assuming that the "...installation appears to be a feeble attempt to allow excessive system pressure to drain outside the house instead of the T & P on the water heater discharging because of what appears to be high incoming water pressure", would you agree with his assessment of the need for a pressure regulator and expansion tank? If so, what would you recommend for the valve and tank? The water heater is a standard 40 gallon, gas-fired unit.
  10. LonnythePlumber

    LonnythePlumber Plumber, Contractor, Attorney

    Messages:
    319
    Location:
    Wichita, Kansas
    Looped

    I had not seen the 210 before and it did throw me for a loop. I appreciate understanding this alternative that we have not been offering in my area.
  11. e-plumber

    e-plumber DIY Senior Member

    Messages:
    137
    Location:
    New York
    Testing Water Pressure

    "e-plumber,
    I am just a long time do-it-yourselfer and hope that my questions are appropriate. Regarding your last post, I'll check the meter for a check valve and test incoming pressure at the hose bib closest to the main shutoff. What is the best place/procedure for testing the in system pressure due to thermal expansion?"

    To get an accurate pressure reading while thermal expansion is occuring, run the hot water at a faucet until the WH burner kicks on, then shut the faucet. After the water heater burner shuts automatically, hook up the pressure gauge to the drain valve on the water heater, you might want to flush any debris build up from the bottom of the WH first and make sure the drain valve is operational.
  12. Terry

    Terry Administrator Staff Member

    Messages:
    14,994
    Location:
    Bothell, Washington
    "Terry,
    If the second relief valve is due to a code situation as you described, wouldn't it be installed on the cold water supply uphill from the water heater instead of on the downhill hot water line? The house is in the Seward Park section of Seattle, so you may be familiar with applicable codes."

    In Seattle, it would go on the hot side anywhere you can find a convenient place to drain it to the outside. If the water heater has one that drains to the outside, then the second one is not needed.
    If you are not sure, you can replace the 125 psi relief that is in line.
    You can check water pressure at the house with a gauge, and if it is more than 80 psi, then a reducer would be needed and an expansion tank.
    Of course once you add those, then the washer, icemaker and dishwasher will need hammer arrestors.
  13. LonnythePlumber

    LonnythePlumber Plumber, Contractor, Attorney

    Messages:
    319
    Location:
    Wichita, Kansas
    Air Chambers?

    My area doesn't use PRV or expansion tanks so I have learned from the rest of you. But Terry are you now adding that if there is a closed system you not only need an expansion tank but also air chambers?
  14. Terry

    Terry Administrator Staff Member

    Messages:
    14,994
    Location:
    Bothell, Washington
    [​IMG]
    You can't use air chambers unless you have a way of draining them.
    We are allowed to use a "shock arrestor"
    Sioux Cheif makes Mini Resters that are allowed.
    It's a sealed tube with a piston. They can't be water logged like an air chamber.
  15. LonnythePlumber

    LonnythePlumber Plumber, Contractor, Attorney

    Messages:
    319
    Location:
    Wichita, Kansas
    Shock Arrestors

    Are shock arrestors necessary or recommended for a closed system?
  16. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,607
    Location:
    Cave Creek, Arizona
    arrestors

    If a device needs a shock arrestor, it does not matter whether the system is closed or open. However if it is a closed system then the recoil and wave degradation is also contained which means it could be more intense and destructive than in an open system, a condition that a shock arrestor could ameliorate.
  17. LonnythePlumber

    LonnythePlumber Plumber, Contractor, Attorney

    Messages:
    319
    Location:
    Wichita, Kansas
    More Coffee

    I'm going to have to drink more coffee before I can grasp all those multi-syllable words.
  18. LonnythePlumber

    LonnythePlumber Plumber, Contractor, Attorney

    Messages:
    319
    Location:
    Wichita, Kansas
    Oh!

    The closed system can aggravate an existing situation.
  19. CharlieG

    CharlieG New Member

    Messages:
    16
    Location:
    Seattle, WA
    So, let me try to recap the situation.
    Terry,
    Assuming that the second relief is rated at 125 PSI (it's installed vertically very close to the basement ceiling and I'll have to use a mirror or pull it off to get a peek at the tag) and from what you've said about the Seattle code, the situation I found was a legitimate setup, (WH's valve drains inside the basement and second valve on the hot side drains outside), and the only immediate problem is that the valve failed and is leaking. Should its replacement be a 125 T & P or just a pressure relief? More generally, if the main pressure is over 80 PSI, a pressure regulator and expansion tank are in order, as well as hammer arrestors at the clothes washer, ice maker, and dish washer. Does the arrestor at the clothes washer install at the cold or hot line?
  20. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    The hammer arrestors are a good idea anywhere you have a solonoid that shuts off the water quickly. Good old Newtons law of physics - a body in motion tends to stay in motion. Those valves shut off almost instantly, the water in the line wants to keep going. The arrestor acts like a shock absorber to keep it from banging against the now closed valve. If the pressure is high in the pipes, it can put a lot of stress on the joints/valves. The expansion from heating the cold water back to hot in the hot water heater can stress things, too. That is why, if you have a pressure reduction valve that acts like a one-way valve as well, that an expansion tank is a good idea, too. The incoming cold water expands as it is heated in the hot water tank, and with the one-way properties of the reduction valve, it can't do anything except increase the pressure. This can cause things to break at the weakest point, or valves to leak. And yes, if you are going to put them in at the clothes washer, put one on the cold as well - Newton doesn't care about the temp in this case!
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