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Thread: Inline TPR valve???

  1. #1
    DIY Junior Member CharlieG's Avatar
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    Default Inline TPR valve???

    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 by CharlieG; 09-30-2004 at 01:16 PM. Reason: Typos?
    CharlieG

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    DIY Senior Member e-plumber's Avatar
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    Exclamation Temperature & Pressure Relief Valve


    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.
    e-plumber

  3. #3
    DIY Junior Member CharlieG's Avatar
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    Default 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?
    CharlieG

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    DIY Senior Member e-plumber's Avatar
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    Lightbulb 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.
    e-plumber

  5. #5
    Plumber jimbo's Avatar
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    Default

    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.

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    DIY Junior Member CharlieG's Avatar
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    Default 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.
    CharlieG

  7. #7
    Plumber jimbo's Avatar
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    Default

    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.

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    Forum Admin, Expert Plumber Terry's Avatar
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    Default

    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. #9
    DIY Junior Member CharlieG's Avatar
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    Default

    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.
    CharlieG

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    Plumber, Contractor, Attorney LonnythePlumber's Avatar
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    Default 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. #11
    DIY Senior Member e-plumber's Avatar
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    Lightbulb 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.
    e-plumber

  12. #12
    Forum Admin, Expert Plumber Terry's Avatar
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    Default

    "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. #13
    Plumber, Contractor, Attorney LonnythePlumber's Avatar
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    Default 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. #14
    Forum Admin, Expert Plumber Terry's Avatar
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    Default

    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. #15
    Plumber, Contractor, Attorney LonnythePlumber's Avatar
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    Default Shock Arrestors

    Are shock arrestors necessary or recommended for a closed system?

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