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Discussion Starter · #1 ·
Strange problem.

Water pressure in the normal range most all of the time, indicating reducing valve is doing its job.

But then someone takes a shower and like magic, pressure shoots up to like 2x normal (street pressure perhaps), which is relieved only by letting water run from one of the sink faucets.

We *at first* thought it was a reducing valve issue and replaced it, but the problem still exists.

:mad:

What might be at issue?

TIA.
 

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Mabe more city pressure than the regulator can handle.. What is the incomming pressure b-4 the reg. ? what are the inlet pressure specs on the reg ?? What is the pressure when the problem occure ( after the reg.)??
 

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Discussion Starter · #4 ·
on city water.

I think city pressure b4 reducer is ~110 (don't quote me - been a while since I threw the pressure valve on it) and reduced was 50-ish psi.
 

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What does the pressure read when the problem you described occures ?? Sounds like the reg. isn't holding the pressure.. That's why I asked about the reg.inlet pressure rating
 

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Discussion Starter · #6 ·
What does the pressure read when the problem you described occures ?? Sounds like the reg. isn't holding the pressure.. That's why I asked about the reg.inlet pressure rating
I did have the reduction valve/regulator replaced and the problem replicated.

I will have to replicate the problem to get that pressure reading. I have only one gauge and it screws on to an outside connection.

Again, looks to be about 1.5 - 2x normal for a brief time and then it reduces. My concern is that it builds and is not relieved in a short amount of time and a connection gives somewhere internally under the increased pressure.

normal pressure shows up as 60 psi (reg. outlet).
 

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Discussion Starter · #7 · (Edited)
What does the pressure read when the problem you described occures ?? Sounds like the reg. isn't holding the pressure.. That's why I asked about the reg.inlet pressure rating
okay - after a shower this morning, the pressure in the system read approx. 140psi.

:eek:


I run the water and it drops back to 60 psi and will hold at 60 until someone takes a shower again.

edited to add:

wonder if the plumber that replaced the pressure red./reg. cut the old one out and simply reinstalled it.

or is it a venting problem?
 

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It is most likely the water heater is building pressure when heating water after you shower. Many communities require backflow preventers causing the pressure to build in your plumbing system. Some regulators even have them built in so you may have one and not know it. To compensate install an expansion tank anywhere it is convent in the cold water side of the system. Just make sure any valve between the water heater and the expansion tank is normally open.


Rege
 

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Discussion Starter · #9 · (Edited)
It is most likely the water heater is building pressure when heating water after you shower. Many communities require backflow preventers causing the pressure to build in your plumbing system. Some regulators even have them built in so you may have one and not know it. To compensate install an expansion tank anywhere it is convent in the cold water side of the system. Just make sure any valve between the water heater and the expansion tank is normally open.


Rege
hmmmm, that might explain why yesterday I would run the shower and not find pressure built up immediately after turning water off but then a bit later pressure had built.

I will investigate more - thx!

edited to add:

pressure at hot water tank after shower was 150.

Yikes!!

Flushed a toilet and it dropped to 50.

will look into installing expansion tank.
 

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Expansion tank

It is most likely the water heater is building pressure when heating water after you shower. Many communities require backflow preventers causing the pressure to build in your plumbing system. Some regulators even have them built in so you may have one and not know it. To compensate install an expansion tank anywhere it is convent in the cold water side of the system. Just make sure any valve between the water heater and the expansion tank is normally open.


Rege
When I moved into my new house several years ago the relief valve on the hot water tank was lifting
Called the plumber and he said due to the back flow preventer on the main it was causing relief valve to pop.
Installed simple little x tank on main line and valve has not popped in 20 years.
 

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If you have 150 psi at the wh & the t&p isn't opening. I would replace it.. at 150 psi the t& p should be wide open.. You can install expansion tank..



I won't say it didn't or can't happen . But,I have never seen expansion of 100 psi from a wh
 

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I think you will find relief valves set to pop at around 190. Water pressure at 150 is not all that uncommon so relief valves would need to be above that to be useful. Where I live it the water comes in at 135 to 145. Check the rating on the relief valve before you replace it. I think you will find 150 psi is not enough to pop it.

Rege
 

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Kenmac is correct. I did some checking and residential relief valves should be set to pop at 150 PSI or 190 degrees Fahrenheit so if your pressure is getting above 150 and the valve is not releasing it should in fact be replaced as kenmac says in his above post.
 

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I use watts brand. (Residental). They are set at 150 psi & 210 deg. Most will start to drip at around 140 - 145 psi & 200-205 deg.
 
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