High water pressure

I am at a loss ! My daughter has water at her house at 160# inside and outside. Two pressure relief valves are running almost a stream each(one outside and one at the water heater) both valves are new. Regulator valves are also new and no amount of adjusting the regs. makes a bit of difference in pressure readings. The regs are rated 300# max-preset at 50# with adjustment from 25 t0 75 #. When I contacted the water Co. I was told the pressure should not be that high but when the service guys came out they said it was fine(maybe because the extra pressure is needed for houses farther up the hill at another 150 or 200 feet elevation) Instructions with the reg. said if pressure readings were approx three times the desired range two should be installed in tandem but I hate to spend another 100 bucks when on reg makes no difference at all Thank you for any suggestions Bill

You seem to be mixing terms when you refer to pressure relief and pressure regulator valves, but let's start at the beginning. First of all, 160 psi is about 3 times too high for inside a home. What is needed to control this is called a pressure regulator valve (PRV). This is a bell shaped brass device that is installed where the main supply line enters the home. This is adjustable and should be set around 60 psi. The T/P valve which I think you are calling pressure relief, is on the water heater. It protects the tank for runaway temperature and excessive pressure. Either of these conditions will cause the tank to explode like a bomb, so they are vital to the system. Now what is causes this valve to leak is the incoming water pressure is already above the 150 psi limit of the T/P, so the T/P is functioning normally. When you install the PRV and set it to 60 psi, that problem will be eliminated, but another problem will be created. Here's what happens. When water is heated, it expands. This water needs someplace to go. In a system that does not have a PRV, this expansion is just absorbed by the city main and there is not problem. This type of system is referred to as an "open system". However, a PRV has a check valve that prevents this expansion from getting into the city main so the pressure will raise and trip the T/P. This is called a "closed system. Fortunately there is an answer. An air charged canister with a bladder called a thermal expansion tank is installed between the water heater and the PRV. This tank is air charged to match the setting of the PRV and absorbs the expansion as needed. I should point out that some PRVs have a bypass to deal with the expansion, and some water meters have a check valve. So if your new PRV has a bypass, you will have to find out from the city if your meter has a check valve. Excessive pressure creates another potential problem. It is very hard on washer hoses, as well as valves and faucets. Just make sure if you end up with a Closed System that you install a thermal expansion tank.

First thank you for yor reply. I am sorry if I caused confusion -- there are two pressure relief valves or pop off valves one is on the water heater and one is outside the house both are leaking a very fast drip. There are also pressure regulators -- one is on a one inch line feeding the whole house and one is on another "mystery line" haven't traced it down yet. All valves and regulators are new. (also the water heater) I am going to see if I can talk to the water dep't face to face because I am useless on a phone. Your info about a check valve sounds like a good bet because there was not ALWAYS a problem. Thanks again Bill

I have no clue as to why you would have 2 PRV and 2 T/P valves. I would venture the opinion that the PRVs are not adjusted at all. Why not turn the set screw on the "mystery" valve closed and see what, if any, water is turned off? Set the pressure on the other PRV to 60 psi and see if that doesn't stop the T/P leak. Put you pressure gauge on a hot water tap and drain the hot water off at another location until the water heater "kicks on" watch the gauge. You will find the pressure rises quite dramatically. If it get to 150 psi, your T/P will open. That will be proof that you need a thermal expansion tank.

The regulators...new or not....are not working, and we are confused by two of them and two relief valves. I recommend turning off the main to the house to prevent a major problem inside. Sound like you need a plumber over there quickly!

With pressure that high, you may need two PRV's, plumbed in series (one right after the other) so that the pressure across each one isn't that high.

Sorry I seem to confuse everbody -- I am not familiar with the term "TP"valve but yes it has to be what I have always heard called "pressure relief valves" because I know the one on the water heater is a requirement for the reasons you explained. The reason there are two I suppose is some plumber felt one outside was necessary(so this must have been a problem sometime in the past) but it was working fine until some weeks ago. I will add the one on the water tank leaked on initial fill up with cold water(of course the outside one did also). There are two regulators I guess because there are two separate lines going into the house(or at least through the outside wall) both have shut off valves before the regs. I know the one inch line turns off the water to the heater and like I said I haven't found where the other line goes yet -- maybe the lawn sprinklers. Can a plumbing supply test a regulator if I take it where I bought it? The house was built in about 1957 and added onto a couple of times and replumbed with copper somewhere along the line. The crawl space is a maze that I cannot navigate.

I seriously doubt that a true plumber installed 2 T/P valves. This has the sound of a hack handyman. A T/P valve has to extend inside of the water heater. Putting one outside would serve no purpose. If that "mystery line" is for irrigation, I suspect you have the potential for cross contamination. I think with all of the unknowns you have, it would be prudent to hire a plumber to check things out. It is difficult to do a proper evaluation on line. Make sure he is licensed and not just a handyman that says he does plumbing.

Nobody installed two TP valves. One is on the water heater as it is on all water heaters.

You would have 2 T&P valves if the drain from the one on the water heater could not be piped to the exterior of the house or if there is no floor drain near the discharge point in the home. 1st one is a 150psi on the water heater and the 2nd is a 125psi on a hot water line above the water heater that could be drained outside. As far as placing the 2nd valve itself outside not just piping the drain there is a mystery.

OK Thank you all -- Now all mysteries and locations and reason for them aside -- Fact #1 The present set up has been working fine for years. Fact #2 Suddenly I have two separate TP(or pressure relief)valves that are running water -- this is what they are designed to do as safety devices. Fact #3 The water pressure is 160# on both side of the pressure regulator. Fact #4 The pressure regulator valve is no longer doing it's job. After our discussions I believe there are only two things that can cause this, either the regulator itself is shot(and I have replaced it with a new one which also runs water) or there has been an increase in pressure at the meter causing the valve to be ineffective. I'm going to tackle the water dep't. and also hash it out with the plumbing supply where I bought the regulator. Thank you all very much -- Bill