Water pressure spikes

[frodo]

I'll end with why a TET is now code and your refusal to accept it?

...forgot...

THANX for all that you taught me!

the discussion was not about if a expansion tank is required or not.

so I was not addressing that.

I will at this time.

as long as it is repair work, and the repair work is installed per code
i am not required to install a expansion tank.
unless i change out the water heater itself.


101.5.1 Additions, Alterations, or Repairs. upc

Additions, alterations, or repairs shall be
permitted to be made to any plumbing system
without requiring the existing plumbing system
to comply with all the requirements of this code,
provided the addition, alteration, or repair
conforms to that required for a new plumbing
system. Additions, alterations, or repairs shall
not cause an existing system to become unsafe,
insanitary, or overloaded.

 

[skelly716]

................................................
whaaaaaaa.......

now, look,,,,a prv is set at 45 psi in your house,
prv.s are not supposed to let the pressure get above what it is set for, it it does, it is a faulty pvr

you have not solved the underlying problem, all you have done, is fixed the symptoms

at 45 psi you do not need a expansion tank

Only need a expansion tank if you have a pressure regulator, check valve or any devise that will cause a "closed system". PRV's are NOT the reason for an expansion tank.

 

[skelly716]

water commission has been known to pop relief valves in hot water tanks when servicing main lines. Expansion tanks are put in place to act as shock absorbers.

Installing an expansion tank will always help and will never hurt I say.

 

[Matt30]

I won't argue that. But whether or not it's required is a different story.

 

[frodo]

I also agree having a tank is a good thing. that was not what this was about

The International Residential Code (P2903.4.2) requires the installation of an expansion tank on a hot water tank where thermal expansion may cause an increase in pressure. The tank is only required when the water supply system incorporates a backflow prevention device, check valve or similar device.

EXPANSION TANK
[UPC 608.3] Any water system provided with a check valve, backflow preventer,
or
any other normally closed device that prevents dissipation of building pressure back into the water main
shall be provided with an approved, listed, and adequately sized expansion tank or other approved device
having a similar function to control therma
l expansion. Such expansion tank or other approved device shall
be installed on the building side of the check valve, backflow preventer, or other device and shall be sized
and installed in accordance with the manufacture’s recommendation

 

[KULTULZ]

OK...

Just for shiats and grins and as no one here seems to be able to follow an argument logically, becoming overly defensive and w/o getting their panties in a wad, let's try it this way-

1) Let's say that the OP supply pressure is 90PSI (truly a guesstimate on the suppliers part as pressure will vary in different parts of the system and by time of day/night).

2) The OP measures 90PSI not aware of varying supply pressure(s), whether an thermal expansion event is taking place and/or assumes there is no back-flow device at the PRV. He has installed a TET suspecting THERMAL EXPANSION and the pressure situation has normalized.

3) He now needs to allow the WH to cool and gauge the PSI within the system and gauge the supply PSI (before PRV) within a few minutes of one another.

If the TET has not actually solved the problem (gauging indicates faulty PRV), I will kiss your butt in the public square and give you thirty minutes to draw a crowd.

Now a second theory question. Is a properly functioning TPRV calibrated to release pressure gradually up to and including it's rated release value or just rated release value?

 

[KULTULZ]

Now a second theory question. Is a properly functioning TPRV calibrated to release pressure gradually up to and including it's rated release value or just rated release value?

Thermal Expansion

One of the more common question regarding T&P relief valves is why they drip. In most cases, dripping is caused by thermal expansion. When water is heated in a closed plumbing system, it expands, causing an increase in pressure. This increase in system pressure over that regulated by the pressure reducing valve is called thermal expansion pressure.

The T&P valve is a safety device and is not intended for continuous operation to relieve thermal expansion.

Continuous dripping can cause the build up of mineral deposits on the valve and may render it useless.

A simple way to detect whether or not thermal expansion is the cause of a dripping relief valve is to open a fixture during the expansion period. Opening a fixture opens the system, and immediately the pressure will drop back to normal. A second method that is used to determine the maximum pressure of the system is to install a pressure test gauge with a telltale on a hose bibb connection. As the pressure increases, the gauge moves the tell-tale. By leaving the gauge on the system for 24 hours, the telltale will remain at the highest pressure registered on the system.

WATTS-

That answers my question.

 

[frodo]

OK...

Just for shiats and grins and as no one here seems to be able to follow an argument logically, becoming overly defensive and w/o getting their panties in a wad, let's try it this way-

you mean you are butt hurt because no one is agreeing with you

1) Let's say that the OP supply pressure is 90PSI (truly a guesstimate on the suppliers part as pressure will vary in different parts of the system and by time of day/night).

2) The OP measures 90PSI not aware of varying supply pressure(s), whether an thermal expansion event is taking place and/or assumes there is no back-flow device at the PRV. He has installed a TET suspecting THERMAL EXPANSION and the pressure situation has normalized.

3) He now needs to allow the WH to cool and gauge the PSI within the system and gauge the supply PSI (before PRV) within a few minutes of one another.

If the TET has not actually solved the problem (gauging indicates faulty PRV), I will kiss your butt in the public square and give you thirty minutes to draw a crowd.

Gawd Damn,
see if you can logically, figure this out, you just stated the prv is faulty, proven by a gauge, so now you say installing an expansion tank has solved the problem, THAT statement in itself proves you are wrong,
the problem is not solved, only the symptom is masked.

AND,,,the prv is still faulty, now what will happen ?
city water pressure fluctuates, His is [according to city] set at 90 psi, at night, when every one is in bed, the city pressure jumps up, because it is not being used. this happens in every town all across the US.
it can jump as high as 200 psi.. You have left a faulty prv in the house, it will continue to be faulty,,and it will completly fail at night when it is hit with a high psi from the city, if it is over 100lbs the T&P will start to dribble, IF it is over 150 lbs, it will fully open.





Now a second theory question. Is a properly functioning TPRV calibrated to release pressure gradually up to and including it's rated release value or just rated release value?

cut and paste from Watts
What is the proper pressure setting for the pressure side of
a T&P valve or for a separate pressure relief valve?
The correct setting for the pressure part of any relief valve is at least
20 to 30psi above the maximum working pressure in the system. If a
setting is too close to the actual working pressure, it causes unnec-
essary and annoying drippage due to water
flucuations and water hammer conditions.
A standard pressure setting of 150psi, for
example, is suitable for use on today’s water heaters, most of which
have a standard working pressure of 150psi. If the working pressures
exceed 125psi, a pressure reducing valve is recommended to reduce
the system pressure to around 45 to 50psi. Then a standard set valve
can be used.
View attachment 14032

 

[KULTULZ]

It is not that no one agrees with me, as I could care less. What the OP did was consistent with no/defective TET.

It doesn't matter as I understand the theory now. Whenever a situation is presented here, there will be several views and procedures offered. My mistake was referencing two separate threads together. My bad. It caused confusion.

BTW- You TPRV info has nothing to do with what I asked. I found the correct answer and posted that I found the correct answer.

But again, I have learned a lot from you and others and I deeply appreciate it.

 

[Mr_David]

I'm trying to figure out what is causing spikes in my water pressure in my home. i have my PRV set to 45 psi, no expansion tank, no back flow preventer or check valve. Street pressure according to water company is around 90 psi.
I've installed a pressure gauge with the red pointer on an outside faucet that shows pressure max and have seen it as high as 90 psi. Just cracking a faucet sends it back to 45 psi. Could my water heater still be the problem? Could my three year old PRV intermittently be leaking by? Should I even worry about this?

90 psi. if you had 80 psi and no prv you would be in compliance with most local codes. 10 more psi is not going to break the bank. Yes it's high.

However. The fluctuation from 45 to 90 may cause premature fatigue of the water heater tank.

What is about Thermal Expansion that you do not understand ...

(Standby Mouseketeers... I feel a long knock-down slug-fest coming... )

Water heater control failure or malfunctioning PRV's are not the reason for an expansion tank. As soon as water is heated it expands. ... If a water heater continues to heat, and a PRV is in place, the pressure can cause the heater to fail. The T&P valve is supposed to protect against this. T&P is actually there to prevent a catastrophic event if the thermostat failed and continued to heat the water beyond it intended temperature. since the W/H was not off, and the pop off did not pop off, that is an indication that the problem is a bad prv I would disagree with the your conclusion that WH was not off and pop off did not pop off would indicate a faulty PRV. That is a premature conclusion.

do you understand how to gather facts and give a correct diagnosis ?

if the pop off was poping off, that would tell you the water was expanding, with no where to go. but it did not
so, that tells me it is not expansion..Water heater expansion does not necessarily have to exceed the T&P rating and pop off[/COLOR

next fact

the system was creeping up to the SAME psi as city pressure outside HMMMMMMMMM..if it were expansion, this would not happen
Why could thermal expansion not creep up to the same pressure as the city side. if the PRV had a bypass thermal expansion could match city side pressure and if expansion continues then the excess would bypass back into city. if no bypass or backflow valve then house side could actually exceed the city side.




all the symptoms for this point to a bad prv.

I Agree that it is most likely the PRV, but Your conclusion is premature.
I am responding to this after I read the slug-fest

................................................
whaaaaaaa.......

now, look,,,,a prv is set at 45 psi in your house,
prv.s are not supposed to let the pressure get above what it is set for, it it does, it is a faulty pvr
Not true.
you have not solved the underlying problem, all you have done, is fixed the symptoms

at 45 psi you do not need a expansion tank

I agree with the concern for adding expansion tanks if there is a need.
I disagree with having to add one every time you install a water new water heater. I'm not going to get into a debate about what the code says either.
My heads starting to hurt. Someone asked my opinion on this thread, but I had not seen it.
I think KulTulz also jumped to a premature conclusion when he said it must be thermal expansion.

My head is spinning and I have to give up my chair so the wife can pay a couple bills.

 

[Matt30]

I wouldn't exactly call Muhammad Ali vs Pee Wee Herman a slug fest

 

[Mr_David]

After much debate I finally spent the money and installed an expansion tank and now I now longer have these spikes.

Good Job. Don't be afraid to ask for help on other issues.

question, why, in your opinion, would a system that has been working
with out any problems, all of a sudden require a expansion tank ?
would it not be a logical conclusion, that a part of the system has failed ?
would it not be in the best interest of the client to find the part that has failed.?

I agree, the op needs to inspect the system to find the CAUSE
not mask the symptom by installing an expansion, and calling everything good. the original problem still exists,

time for school.
how would he diagnoses that it is the prv causing creep and not expansion ?

OP didn't say It had been working with out problems. If he did I missed it.

If the prv was leaking by, the pressure would continue to increase even with an expansion tank. The addition of the tank would only slow the increased pressure as the water leaks through the PRV, the air bladder will eventually compress to it's capacity and no longer absorb the increase water pressure.

................................................
whaaaaaaa.......

now, look,,,,a prv is set at 45 psi in your house,
prv.s are not supposed to let the pressure get above what it is set for, it it does, it is a faulty pvr

you have not solved the underlying problem, all you have done, is fixed the symptoms

at 45 psi you do not need a expansion tank

If the pressure is not rising or spiking above the desired set point of the PRV then there is no problem to address.

I think FRODO was having a bad day. We all get those sometimes.

 

[havasu]

Note to our helpful experts:

We really appreciate all the input you provide and we all know there is more than just one way to "skin a cat", so we appreciate it but ask that if you have other ideas or believe the information you are commenting on is not correct, please do so in a polite format. We are all here to help, but seeing the arguing can be a turnoff to others.

 

[frodo]

Could my three year old PRV intermittently be leaking by?
Thanks, Curtis

Help me out here....Old dawg can learn new tricks.

The Op was satisfied with the pressure for 3 years, He does not say so,,He ALSO, does not say he had a problem with spiking.
SO,,I am left to assume all was well till recently.
WHAT, caused the sudden spiking in the system ?

my point is, if expansion was not a problem before, WHY is it a problem now?

these 2 questions are what drives my belief it is the prv

 

[Matt30]

Installing the expansion tank is putting a band aid on the problem, not curing the actual problem.

 

[frodo]

Installing the expansion tank is putting a band aid on the problem, not curing the actual problem.

that is my theory also.

 

[Mr_David]

You asked

Original post

Nothing here says the problem all of a sudden started happening.
He does not say he has been monitoring this on a regular bases.
He did mention the PRV was only 3yrs old.

You are reading into the problem facts that are not stated.

I'm trying to figure out what is causing spikes in my water pressure in my home. i have my PRV set to 45 psi, no expansion tank, no back flow preventer or check valve. Street pressure according to water company is around 90 psi. I've installed a pressure gauge with the red pointer on an outside faucet that shows pressure max and have seen it as high as 90 psi. Just cracking a faucet sends it back to 45 psi. Could my water heater still be the problem? Could my three year old PRV intermittently be leaking by? Should I even worry about this?
Thanks, Curtis

After much debate I finally spent the money and installed an expansion tank and now I now longer have these spikes.

Help me out here....Old dawg can learn new tricks.

The Op was satisfied with the pressure for 3 years, He does not say so,,He ALSO, does not say he had a problem with spiking.
SO,,I am left to assume all was well till recently.
WHAT, caused the sudden spiking in the system ?

my point is, if expansion was not a problem before, WHY is it a problem now?

these 2 questions are what drives my belief it is the prv

We don't know if there was a problem before he started checking it with a gauge. He never said he was checking it on a regular bases. You may have assumed that.

It's tough to diagnose a problem with a brief description or even when we are standing in front of it.
Often we inject things that we think fits because we have seen similar problems so many times before.

It is very uncommon for anyone to regularly check their water pressure unless they are experiencing a noticeable problem.

Installing the expansion tank is putting a band aid on the problem, not curing the actual problem.

If the pressure is not spiking past the desired set point, What is the problem?
You can't hide a faulty PRV with an expansion tank. If the PRV is leaking by then the pressure will eventually equalize on the house side to the available pressure on the street side.

 

[Valveman]

if the pop off was poping off, that would tell you the water was expanding, with no where to go. but it did not
so, that tells me it is not expansion..

next fact

the system was creeping up to the SAME psi as city pressure outside HMMMMMMMMM..if it were expansion, this would not happen

all the symptoms for this point to a bad prv.

Well I have to disagree a little bit. If the pop off was not "popping off", it is either a bad pop off or it is just set higher than 90 PSI.

And not only can thermal expansion cause the system pressure to creep up to the same as city pressure, but it can creep up even higher than city pressure.

You got the right word with "creep". All PRVs have "creep". They will eventually let enough water creep through to cause the pressure to spike. As long as the PRV regulates to 45 when some water is flowing, the PRV is good.

A thermal expansion tank only has to absorb a small amount of water to keep the pressure from increasing due to thermal expansion.

You can also get a PRV with a thermal bypass. This will let water go backwards through the PRV when the outlet pressure is higher than the inlet pressure. But it would only keep the expansion pressure below 90 PSI, as the thermal bypass would let the outlet equalize with the inlet pressure.