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Old 11-14-2010, 05:30 PM   #1
joeparocks
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Default Water heater pressure and a back flow valve

I have a water heater that has both a pressure relief valve and a back flow prevention valve (BFP). It seems that the BFP (which is an 80psi) is continuously running. I checked the pressure in the hot water heater and it is 90psi (all the time) which makes sense why the 80psi valve is always open. I checked the hose bibs pressure and initially it was 90psi also. I lowered the whole house pressure and got the hose bibs down to 75psi. No matter what I do the house pressure, the water heater is above 80psi. I open the pressure relief valve on the water heater with the guage attached and saw the pressure go down to 60psi but within 2 minutes it was back to 90psi. How do I get the pressure in the heater down? I would understand if the BFP was leaking hot water (which expanded) but it's leaking cold water from the input line most of the time.

Any advice on what to check, set, or install would be much appreciated...I'm watching hundreds of dollars a year leak down my drain tube at this point.



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Old 11-14-2010, 05:59 PM   #2
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What means did you use to lower the house water pressure from 90 psi to 75 psi? That is still too much pressure, as most homes work great at 50-60 psi. If you don't have a pressure regulator valve installed on your main, this is my first recommendation. If after reducing your pressure, and you still have problems, I'd recommend a thermal expansion tank.



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Old 11-14-2010, 10:14 PM   #3
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Turn the heater off for moment. If you do have a pressure reducing valve (PRV) on the cold water service to house, It may be Defective. With the heater off, you shouldn't have any thermal expansion. Adjust the PRV as low as you can. Then watch the gauge on a hose bib. Open a faucet in the house to relieve pressure, then close it. If the pressure goes back up, then your PRV is leaking by. Preplace it

What kind of BFP valve is it. It dumps water when the oulet side is higher than the inlet?
That's odd to have on the water heater supply. A simple swing check valve is usually used in that application

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Old 11-16-2010, 02:02 AM   #4
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Default Ok...my mistake on the valve!

The valve on the cold water in to the water heater is not a back flow prevention, it is a thermal expansion relief valve (TERV) set to 80psi. As a test, I turned the pressure down on the main line down about as low as it could go...water trickling out of faucets upstairs. The pressure in the water heater still stayed solid at 90psi. When I closed the TERV on the cold water in and then opened a hot water faucet, the pressure went down to a workable 70psi and stayed there (of course no cold water was coming into the tank). This really has me stumped. If the pressure control valve wasn't working, wouldn't it not have affected the rest of my plumbing when I adjusted it? It turns out that my next door neighbor (same heater and setup as me) is having the exact same problem. We are both stumped...

I really appreciate the replies and hope that this new info sheds more light for everyone to think up some other possibilities.

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Old 11-16-2010, 03:15 AM   #5
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"I turned the pressure down on the main line down about as low as it could go"

How are you doing this? From a pressure regulator or just partially closing the valve?
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Old 11-16-2010, 03:48 AM   #6
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Default It's a pressure regulating valve

A Wilkins Model 70 pressure regulating valve. Simple bolt valve (25-75psi) range.

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Old 11-16-2010, 03:58 PM   #7
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Mystery?? I Love a good mystery. Gas or electric heater. Did you turn it off Like I suggested
Let's try and be a little more specific.
You turned down the PRV( Wilkens 70) on cold service and water is trickling out of faucet.
Would that be just the cold side only opened or hot side only or both H/C open.
Could you possibly have a second source of water feeding the hot water system.
After you turned down the PRV,
turn off of main water at PRV,
turn off heat to heater and releave all pressure from both hot and cold systems.
put a gauge on cold hose bib and on heater. Both should be "0"
Slowly turn main water back on and adjust PRV up to about let say 50 psi.
Both gauges should show 50 psi.
Is there a check valve on the cold supply to heater.
If no check valve and you turn off the main cold supply and open just the cold side of a faucet then both gauges should drop to "0" If gauge on heater does not drop then you most likely have a check valve somewhere near the heater isolating the two systems.
Can you take some pictures. Pictures are helpful.

Is this the type of TERV valve you have. I'm not sure what you meant when you said you closed the TERV

530C.jpg  
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Old 11-17-2010, 12:40 AM   #8
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Default Images to help...

I'm uploading some pictures of the situation. I need to go and get a second guage to run the test you described. But in the mean time, here are the images of the heater, the thernal expansion relief valve, the pressure relief valve and the pressure regulator.

There is a shutoff on the TERV (the yellow plastic covered handle)...That's where I shut it off for the test I ran. I will get back to you on the results of the test you suggested. I'm trying to find a second guage, pretty sure my neighbor has one too since we're fighting the same battle.

DSCN2551.JPG   DSCN2552.JPG   DSCN2553.JPG   DSCN2554.JPG  
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Old 11-17-2010, 10:24 PM   #9
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Nice pictures. I'm gonna try to break down what your trying to describe

"thermal expansion relief valve (TERV) set to 80psi.
As a test, I turned the pressure down on the main line down about as low as it could go...water trickling out of faucets upstairs.
The pressure in the water heater still stayed solid at 90psi."
Was the TERV (yellow handle closed) while taking reading of WH pressure?

When I closed the TERV on the cold water in and then opened a hot water faucet, the pressure went down to a workable 70psi and stayed there (of course no cold water was coming into the tank).

70 psi on the cold or hot side???
Did you adjust the PRV back up?
If not where is the 70 psi coming from?If you turned down the regulator to a trickle, then it should be the same on both the hot and cold side with the the TERV open. If the TERV is closed and you open a faucet on hot, gauge on water heater should drop to ZERO
It's either your description or something's missing.


If the pressure control valve wasn't working, wouldn't it not have affected the rest of my plumbing when I adjusted it? It turns out that my next door neighbor (same heater and setup as me) is having the exact same problem. We are both stumped...
Do you know for sure the PRV controls all water to fixtures and to water heater and there is not a second source of water to the heater?
I hope I am not confusing you more
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Old 11-19-2010, 06:31 PM   #10
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Was the TERV (yellow handle closed) while taking reading of WH pressure? Yes...and as long as it stayed closed the pressure didn't spike back up.

70 psi on the cold or hot side??? I was reading the pressure at the water heater.
Did you adjust the PRV back up? Yes I adjusted it back up.

Basically, what I am thinking now is that the pressure regulating valve for the main line is malfunctioning in allowing pressure to increase in the line. Whatever I have the PRV set to (low, regular) if the yellow handle (TERV) is closed the pressure stays good in the water heater. As soon as I open that valve and the cold water fllow is open again to the heater, the pressure increases to about 90psi in the heater...There is only 1 PRV. It's really a simple set up (see pictures). I've also heard yesterday from one of my neighbors that he had the same issue had a plumber come out and replace his PRV and the problem went away. He also put an expansion tank on the water heater (which I guess is code now in VA).


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