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Old 08-11-2008, 01:05 AM   #1
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Leaking pressure relief valve


My 5 year old Maytag GAS water heater was leakng steadily from the PRV - so I replaced it, fired up the heater and the new one stared leaking as soon as the water temperature got warm again. It's a steady drip from the relief valve. I asked a friend who told me to check the pressure on my main line. So, I will go buy a gauge tomorrow and check it.

Thinking ahead... If the main line pressure is high (which is what? more than 70 PSI?) then the next challenge is finding the main control value. My house is on a slab and I don't know if my house even has a main control valve - nor do I know exactly where the main water line comes into the house under the slab.
Does any one know any tricks to finding the main line control valve without tearing out a lot of wall board? And what amount of pressure is considered high water pressure to where the control valve needs to be set lower or replaced?
Any help at all will be greatly appreciated.
Chris

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Old 08-11-2008, 01:19 AM   #2
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Leaking pressure relief valve


I'm not a pro plumber, just a long-time DIYer, but here's my two cents.
Usually, you can locate your main line in line from your meter straight to your home. Your main shut-off valve may be at the meter (toward your home), or near the base of your home, or looped up in a utility room or closet inside your home, but you can always cut the water off at the meter itself with a meter key or small wrench.
Look for an oblong brass valve stud that the meter keys fits onto on the public side of the meter. Leave a faucet running so that you can watch the little "leak indicator" triangle on the meter. If it's spinning, the water is on and running. When the little triangle is stopped, the water is off.
Call the public water works people and ask what their pressure is at your meter. Put a water pressure gauge on a hose bibb and check the pressure with the water off and with the water running.
If it is well above 60 psi, you may want to install an adjustable Pressure Reducing Valve near the meter. If you install a PRV, you create a closed loop system, which also usually requires a small expansion tank on the supply line at your water heater.
Good luck!
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Old 08-11-2008, 01:35 AM   #3
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Leaking pressure relief valve


Look on the tag on your water heater's pressure release valve. It will normally tell you the pressure and temperature rating of your PRV.

I can't say I recall correctly right now, but the tag on my old water heater's prv was about 150 psi and 200 deg. F. So, connect a pressure gauge to your hot water heater's drain valve and see if the pressure is close to 150 psi. If it isn't anywhere near there, you might just need to replace your PRV. If it is, then there's a good chance that you need an expansion tank on your hot water supply piping.

Water is strange. It is almost unaffected by pressure, but will expand significantly when heated. So, when you get cold water into your water heater and heat it up, it expands and creates pressure inside your hot water heater that can easily exceed 150 psi. So, your PRV valve drips to release that pressure.

By installing an expansion tank, the expansion of the water goes into stretching a rubber bladder inside the expansion tank instead of forcing open your hot water heater's PRV.
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Old 08-11-2008, 08:06 AM   #4
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Leaking pressure relief valve


Doesn't water only expand about 4% when heated or frozen?
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Old 08-11-2008, 08:20 AM   #5
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No, water is at it's densest at 4 degrees above freezing.

H2O expands by about 10 percent when it freezes, which is why about 10 percent of an iceburg is above the water line and 90 percent below. (It's the only stuff we know of that expands when it freezes.)

But, liquid water also expands as you heat it. That is, cool water expands when you warm it as well. I don't know off the top what the coefficient is.
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Old 08-11-2008, 01:18 PM   #6
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Mike and Nestor, Your information is helping a lot. I'm getting a plumbing, mechanical and chemistry lession all at once. Ok. I checked the tag on the new pressure relief valve I just installed and it does read 150 PSI and 200 degrees. I know the water is not 200 degrees because I can let it run on my hand right out of the drain valve without burning me. I bought the pressure gauge at lunch and will check the pressure tonight. I also found where the main supply line comes into the house. These is a shut off valve that is behind the water heater itself and was hard to see (really bad placement for that valve). The shut off wheel is sticking thru the wall board. So, I shut it off and sure enough - all the water in the house was shut off. I cut away some of the wall board around the shut-off valve. I don't see a pressure reducing valve near that shut off valve, but there is a 3/4" to 1/2" tee that branches about 1 foot above the shut off.

Now that I've found the main line, let me ask this. If the pressure is high - 150 or so - more than the limit of the relief valve - is there any reason why I should not install a pressure reducing valve either above or below that shut off valve - as long as I install it on the main line before the line branches to other parts of the house - AND even if there is already a pressure reducing valve somewhere above or below the point where I install a new one - in other words, does it matter that an old, no-longer-working pressure reducing valve might already be on the main line somewhere above or below the point when I am able to install a new one?

Once more question on Nestor's info. Once the water temp has reached the high point and started to expand and the thermostat shuts off the gas, and the water continues to come out of the relief valve indefinitely with no gas running, and I have a new valve on the water heater, wouldn't that indicate that the pressure to house must be higher than 150 psi? Also, thanks for the tip of using the pressure gauge to the hot water heater's drain valve. I hadn't thought of using that - what better place to test it! I will check that tonight and go from there.
Thanks again guys,
Chris
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Old 08-11-2008, 02:17 PM   #7
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Leaking pressure relief valve


Chris:

The P&T relief valve MAY be leaking because of high pressure in your system, but not likely. Most likely it's because some dirt has gotten under the seat of the valve, and is holding the valve open slightly. Try popping the manual open lever on top of the valve a few times with a pail under the discharge pipe to see if you can get the dripping to stop.

If the dripping only happened when the hot water heater was firing, then I'd say it may be due to water expansion. But, if it's dripping all the time, it's probably just dirt in the valve.

P&T relief valves are notorious for leaking after you check them. You often have to pop them open and let them close a half dozen times before you can get them to stop dripping. It's a good idea to install an expansion tank to allow for the expansion of your water as it's heated, but that won't necessarily stop your P&T valve from leaking if there's dirt in it.

You said: "I know the water is not 200 degrees because I can let it run on my hand right out of the drain valve without burning me."

That simply means that your dip tube isn't broken. The cold water goes into the hot water heater at the top. But there is a DIP TUBE that directs the incoming cold water to the bottom of the water heater. That's cuz if the cold water came in to the heater near where the hot water goes out, then the cold water would immediately head for the outlet whenever you draw on hot water, and you'd get a mix of hot and cold water. The dip tube carries the cold water to the bottom of the heater so that it's greater density results in more efficient displacement of the hot water above it into the hot water outlet. Thus, if you release water out the drain valve of your heater, you SHOULD get a mixture of hot water from the tank and cold water from the dip tube, resulting in only luke warm water. If your dip tube was broken, you'd get luke warm water out the hot water outlet and hotter water out the drain valve.
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Old 08-11-2008, 03:09 PM   #8
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Leaking pressure relief valve


Nestor, Thanks again. I follow what you're suggesting. I do now understand why the temperature could be high but not be noticable at the prv. Where is the best place to test the temperature - would it be the nearest hot water faucet?
Also, I read an earlier thread you or someone had written before I posted my first one - which is the reason I went and bought a new prv right away. Before my first post, I had already tried clearing the prv of any debris by snapping it open and closed several times - per the advice to another posting.

I 2 more clues. My wife called a moment ago. She had started the clothes washer and then walked into the garage and noticed the prv was no longer leaking like ti had been - it was now only slightly dripping. She didn't touch the valve itself. She called me right away. She was using the hot water cycle on the washer. I asked her to shut off the washer for a moment and go check for the prv again. Sure enough, it started leaking again - slowly at first, then it speeded up to the same steady trickle.

Then I asked her to turn on the hot water in the sink. Same pattern. The prv leak almost stopped completely - then started up again when she turned off the sink faucet. She also felt the water temp from the sink and it was not overly hot - the usual 120 degrees or so.

Would all of these conditions support the notion that the main house pressure is too high and the clothes washer running was releasing the pressure to the prv? Or, could it be that the water is hotter at the prv sensor then at the kitchen sink and cold water running into the water heater cooled off the prv temporarity?

I'll know a lot more tonite when I check the pressure with the gauge at the water heater drain.
Regardlese of how this turns out - it's really nice to be able to talk to really knowledgeable people about this problem - and rather interesting that I might actually gain the knowledge that I need to fix this problem myself - solely from this site.

Chris Magee
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Old 08-11-2008, 04:28 PM   #9
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Leaking pressure relief valve


If turning on the water at a hot water faucet or turning on the washing machine slows the rate of dripping from the PRV, then I agree the problem you're having is that the working pressure of the heater is too high.

Perhaps you HAVE a pressure reducing valve on your house's water supply pipe, but it's adjusted way too high.

Where I live, the water supply pressure is only about 20 to 30 psi. But, in cities in mountainous regions, there can be a 300 foot elevation differences from one end of a city block to the other. In those cases, for the pressure at the top of the hill to be 25 psi, it has to be 155 psi the bottom of the hill. So, what they do is install pressure reducing valves on those homes at the bottom of the hill so that the upstream pressure is 155, but the pressure on the down stream side of the pressure reducing valve is 25 or 30 psi. That way, you have a managable pressure in every house on the hill.

Perhaps your house already has a pressure reducing valve, and it's busted.

I'd check the pressure at the drain valve on your water heater. If it actually is 150 psi, then your house SHOULD have a pressure reducing valve on the water line going into your house.

The best place to check the temperature of the water in your tank is at the closest hot water faucet. Let the water run a bit for the cooled water to get flushed out of the lines and for the lines to warm up, and then stick your thermometer into the water stream and measure it.

Your hot water heater should NOT be any higher than 145 deg. F at the highest. If you have an infant, turn the water temperature down to 120 or 125 deg. F. You can burn yourself quite seriously with water hotter than 145 deg. F. 130 to 140 deg. F is a good operating temperature for a water heater. The hotter the water in your heater, the less you use of it to make warm water, but the higher the rate of heat loss through the insulation to the surrounding air, so it's a trade off.
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Old 08-12-2008, 12:17 PM   #10
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Leaking pressure relief valve


Nestor,
The mystery is solved. I tested the water pressure last night and the reading was off the scale. The pressure gauge only reads to 100 and the the pressure pegged past the 100 mark. With the info I got from you and a guy at Home Depot, I decided I would try to install a new pressure reducing valve above the shut off valve. When I cut away the wall board above the shut off valve - HARK! - I found the pressure reducing valve hidden behind the wall board. So, I first tried adjusting it in both directions and the pressure gauge did not change. I ran some water out of the system before and after each adjustment, and the pressure stayed over 100 - even when I was running the kitchen faucet. I even went next door and checked the gauge on my neighbor's line and his pressure read about 65. As you described, my house is in a hilly area and is lower area than the surrounding neighborhood - near Stone Mountain, GA. The Home Depot guy also convenced me that I should also install an expansion tank - since it's now code in GA. The problem now is - because the old PRV is so close to the back side of the wall board, there's no way to unscrew it from the permanent threaded side of the unit, unless I cut out some of the wall board behind it; so, I'm going to try to hack saw it out - and I'm not that experienced with soldering, but I'm going to give it my best shot before calling a plumber since I'm this close to getting it fixed. Also, because the new unit is shorter than the old one - it won't fit in btw the old pipes without doing some new fitting. Seems like they would make an adapter that would fill the space left by the smaller unit; so no new cutting and fitting is needed.
Also, now that I know it's the pressure - I should have thought to mention something else. Last weekend, the ice maker line blew out and a lot of water ponded on the kitchen floor before I found it. At the time, I thought it was because the thin flexible line had just become brittle from the heat from the back of the frig; but, now I know it was probably due mostly to the sudden increase in pressure form the bad PRV.
I wanted to let you know how much I appreciate all of your help.
Yours, Mike's and the Home Depot information helped me solve the mystery in multiple ways - determining the exact problem, finding the pressure reducing valve and debugging the problem without causing more damage.
What a great concept this DIY website is for novices like me who like to try to do-it-themselves.
If I can ever help you with any woodworking, electrical or roofing questions - which I know a lot more about then plumbing..., feel free to email me at chris30044@yahoo.com.
Thanks again,
Chris
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Old 08-12-2008, 02:12 PM   #11
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Quote:
Originally Posted by Chris Magee View Post
Nestor,
The mystery is solved. I tested the water pressure last night and the reading was off the scale. The pressure gauge only reads to 100 and the the pressure pegged past the 100 mark. With the info I got from you and a guy at Home Depot, I decided I would try to install a new pressure reducing valve above the shut off valve. When I cut away the wall board above the shut off valve - HARK! - I found the pressure reducing valve hidden behind the wall board. So, I first tried adjusting it in both directions and the pressure gauge did not change.
Before replacing that pressure reducing valve, try to find out who made it and contact the company for instructions on how to adjust it. It still may be perfectly functional, just completely out of adjustment.

(Sometimes I think that people who indiscriminately drywall over important valves or install flooring over basement clean outs and stuff like that must be the same people that appear as guests on the Jerry Springer show.)

Quote:
I ran some water out of the system before and after each adjustment, and the pressure stayed over 100 - even when I was running the kitchen faucet. I even went next door and checked the gauge on my neighbor's line and his pressure read about 65.
There's no need to have your house's water pressure any higher than 30 psi. In fact, if it's a single level house, even 15 to 20 psi is way more than you actually need.

Quote:
The problem now is - because the old PRV is so close to the back side of the wall board, there's no way to unscrew it from the permanent threaded side of the unit, unless I cut out some of the wall board behind it; so, I'm going to try to hack saw it out - and I'm not that experienced with soldering, but I'm going to give it my best shot before calling a plumber since I'm this close to getting it fixed.
I think you might want to leave this one to a plumber. Your main water shut off valves might leak, in which case you might not be able to solder.

If you're new to this house, what might be a good idea is to hire a plumber to both replace the pressure reducing valve AND install new water shut off valves on each side of it so that when you shut the water off to your house, you know the water will be completely shut off and you won't have a problem soldering. I'd install ball valves as shut off valves. They're the most reliable shut off valve you can buy.

Also, if you have room, install a ball valve not only upstream of the PRV, but a pressure gauge, drain valve and another ball valve downstream of the PRV. That is:

ball valve - PRV - pressure gauge - drain valve - ball valve

Install the drain valve so that it points UP, to prevent introducing air into your drain piping. Cover with a plastic cup when not in use to prevent dust getting into your drain valve.

That way, you can:
1. close both ball valves and release the water pressure with the drain valve.
2. turn your PRV all the way down (to 10 psi say)
3. open the upstream ball valve
4. adjust the PRV until the desired pressure shows on your pressure gauge (because of the very small volume of piping being pressurized, you will see an immediate response on your pressure gauge as you turn the PRV's adjusting screw to increase the pressure)
5. Now, open the downstream ball valve and the PRV will then pressurize the whole house's water supply system to that same pressure.

Having your plumbing set up this way allows you to very accurately set the water pressure in your house because the PRV will pressurize the whole house to exactly the same pressure you set in Step 4 when pressurizing a much smaller volume.

Maybe hire a plumber to do this, and you'll have complete and accurate control over your house water pressure from now on. If you don't quite understand how this set up will allow you to do this, post again.

If you have a hot water heating system in your house, I highly recommend you set up the pressure reducing valve on the feed water line to the boiler exactly the same way so that you can quickly and accurately set the pressure your heating system operates at.

If you're new to DIY, you might get yourself into trouble over your head on this one if you cut the old valve out, and then can't solder the new one in because the shut off valves are leaking. If you have to hire a plumber to replace the shut off valve to your house (and do the rest of the piping for the PRV) then you avoid a major problem many new home owners have to contend with, and that's a leaking main water shut off valve so they have trouble soldering.

You will find that 90 percent of the cost of maintaining your home can be saved by doing simple and straight forward stuff yourself. If you can't solder yet, then I'd let this project fall into the 10 percent category for now. You'll have ample opportunity to save money on other things that will come up that need repairs and attention.

Quote:
I wanted to let you know how much I appreciate all of your help. What a great concept this DIY website is for novices like me who like to try to do-it-themselves. If I can ever help you with any woodworking, electrical or roofing questions - which I know a lot more about then plumbing..., feel free to email me at chris30044@yahoo.com.
Thanks again,
Chris
No problem, Chris. But, before you start cutting that old PRV out, make sure you can't fix it by just adjusting it. Also, the company that made it may make an overhaul kit for it, and that might save a lot of problems. Certainly, make sure that your shut off valve upstream of that PRV works to shut the water off completely before you cut any piping. You don't want to be paying a plumber double to get you out of an emergency you got yourself into. That's counter productive.

Last edited by Nestor_Kelebay; 08-12-2008 at 03:01 PM.
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Old 08-12-2008, 06:06 PM   #12
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Leaking pressure relief valve


Nestor,
The overhaull kit is something I didn't even know existed. I'll try to find the name on the unit. If it's on the far side - it's so close to the back drywall that I won't be able to tell without removing it or cutting a section out of the other side of the wall - which I could do - that wall is in the kitchen closet. I do remember seeing a metal tag near the adjustment screw - so I'll look there first.
I agree with you completely on the type of people that would dry wall over important features - they'd either make great Jerry Springer guests or nutty participants on the Jackass show. It took me 2 days of asking and emailing trying to figure out where it might be hidden and then, when I finally gave up looking and begain cutting a space in the wall to install the new PRV - I found the odl ont unexpectedly.
Also, I think you are right on the level of experience needed for this one. I just tried to call a plumber I used once before and left a message. They were reasonable on repairing my furnace a few years ago - so, I'll probably do what you say and let them handle this tricky stuff.
---------------------
Just curious - say the shut off valve does leak, couldn't I shut off the water at the yard meter and then siphon out any water remaining in the pipe up to the shut off valve? How far downstream from the shut off does the cut off have to be before you can heat the pipe enough to be able to solder on a new coupling? Or - is there such a thing as 3/4" compression fitting that could be installed after the shut off - rather than soldering on a new coupling?
Also, I've copied all of your notes to make sure the plumber knows and agrees with everything you suggested - the psi level, using 2 ball valves, the pressure gauge and the drain valve; the proper ordering - and even moreso, knowing when to walk away from a job I'm not ready to do; which, to be honest, gave me great relief to think about it just being done right - once.
Chris
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Old 08-12-2008, 08:48 PM   #13
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Chris:

A flashlight and mirror might help if the valve is facing the wrong way, but normally the make and model will be on the metal tag.

If you can find the make and model number of the pressure reducing valve, get on the internet and go to the company's website and e-mail their tech support staff from there. You won't be the only one with that PRV, and if there is an overhaul kit available for it, they would know about it. The make and model should be on the metal tag under the adjusting screw. Also, ask if the PRV has a filtration screen. If it has a large hex nut on the bottom of it, removing that hex nut will allow you to remove and replace the brass or stainless filtration screen. If there's an overhaul kit for your old valve, ask them to also send you a coupla filtration screens for that valve, too. And, if there's a gasket under the hex nut that holds the filtration screen in, a few spare gaskets wouldn't hurt either.

Yes, there are ways around leaking shut off valves. People use a lotta Wonderbread. If you have to do any soldering on a 2nd floor, for example, you can just open a valve on the 1st floor to allow the leakage into the piping to drain away. And, there is the strong possibility that you may have two leaking shut off valves in series. With threaded or union connections, you can live with a leaking shut off valve, but you can't solder worth a damn. All I'm saying is that having reliable water shut off valves in a house is truly a blessing when you've lived with leaking ones for a while. Typically, you'd need the water a good 2 or 3 feet away before you could solder.

Also, lots of ball valves now don't have a packing nut on them. The manufacturers have decided that their valves never leak around the stems anyhow, so they're not necessary. Tell your plumber to try to get ball valves that DO have packing nuts so if there is any leakage around the stem, you can tighten the packing nut to stop it. If your valve doesn't have a packing nut, the chances are better that it won't leak, but there's no way to deal with the problem (short of replacing the valve) if it ever starts to leak. For my money, I always buy ball valves with packing nuts. You have to look carefully under the handle to see a hex nut. If you see one, that's the packing nut.


Last edited by Nestor_Kelebay; 08-12-2008 at 08:58 PM.
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