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Water pressure too high causing water heater leaks


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Water pressure too high causing water heater leaks?

I have an instance of water pressure varying from 120 to 140 psi into the water heater (installed new in 2012 - State brand commercial) - the water heater is leaking - reportedly from the heating element seals.

Once I was back home, I started to think that these are pressure vessels and if there were a true overpressure (enough to cause leaks), then it exit through the pressure relief valve.

What are your thoughts?

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IRC recommended water pressure is to be between 40 and 80 PSI.

Pressure over 80 PSI is to be regulated by a PRV (Pressure Regulator) to keep it within the required levels for safe operation.

Extended high pressure will cause undo wear on all valves and seals and they can and will eventually blow out and cause the associated water damage.

Case in point: My brother lives in a retirement community in Central Texas (aka: Del Webb). Original water pressure on his new home (~6 years ago) was right at 70-80 PSI. A couple of years ago he sent me a message that he received from the local city and the notice that they were switching over to a new water tower supply for their community and that the new system would be providing a new static (give or take) water pressure of about 120 to 130 PSI and that they strongly recommended that all homeowners contact the approved plumbers (those approved to work in the community) and get PRVs installed on their incoming water lines.

My brother put it off to save the ~$250 for the installation and PRV. Well about six months later the line for the master bath toilet blew out at 2:00AM. Thankfully he knew where his shut-off valve was and handled it immediately.

After that ... he put on anti-burst lines for the toilets, sinks, clothes and dish washers AND he contacted the plumber for the PRV installation.

He told me of several homes who had some serious flooding with burst lines (due to increased pressure) where the residents did not install the PRVs.

Just FWIW ...

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I concur with others that a PRV is really needed, that water pressure is way to high.

Here's the tag off my WH TPR. It says set for 150 psi so you would think all the seals and container would hold anything below that. If the true average tank pressure is above your one or two readings and the TPR setting you would expect it to leak there (TPR) first.

Best course is to eliminate the pressure problem with a PRV and expansion tank.

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That high pressure may already have stressed the water inlet valve on any washing machine or dishwasher so those valves may need to be replaced as may any flexible hoses. Use braided stainless steel jacketed hoses at minimum. You can get FloodSafe hoses that have a high flow shutoff feature. These, however, are made by man and may fail so nothing is 100% bullet proof.

The TPR should relieve 150psi or 210degrees F for small residential water heaters.


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Thank you gentlemen, this is actually a hotel with booster pump with control issues, when that is controlled properly, the pressure problem will be solved - but I am worried about what I need to do for this water heater that is leaking now.

I guess I am looking for more input on whether you would think the leak is really because of the overpressure or if that would not be the problem - and the leak would be from somewhere else.

Of course this all hypothetical based upon experience because I am not taking the unit apart.

You are all a great help! Thank you!

I always appreciate your insight.

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Yep, the house needs a PRV to lower the city water pressure. Then don't forget to install an expansion tank or valve at the water heater, or the TPR will start to leak!

Scott, I don't think I've seen a pressure reducing valve that doesn't have an expansion bypass for at least 15 years - and very few before then. Makes expansion tank installations a completely unnecessary expense, unless there's actually a check valve installed too.
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