Water Heaters - T & P problems-leaky again!

Replaced T & P on 40 gallon gas water heater about 3 weeks ago-all went well, until water company turned off water for servicing. Now T & P valve leaks-activating it causes water to come out the valve side (not the fittings) When water was turned on, I heard a loud "pop" , then saw a little water on floor-activating the T& P valve caused it to leak more....expansion tank feels full, as well-should mention that water pressure is strong-could that have damaged the T & P valve when they turned water back on at the main?

Valve could be bad due to a surge of pressure when the water was turned back on. You have to get a gauge and check what the pressure is now; anything around 80lb.psi is too high. If you are in that range you will need a pressure reducing valve.

I will check the pressure-are there different T & P valves? Could I have gotten one with a lower tolerance?

Do you have an overpressurization tank installed on the inlet side. It will take a lot of the variances in pressure and stabilize them. It is code in NC, but not here, yet. Should be.

chandler..he said he had an expansion tank..prob the same thing?

Uh-oh, my bifocals must have jumped over that. However, if it feels full, the bladder may have failed, or it is watelogged and needs partial draining to allow for an air headspace. Thanks, GG.
Now, I read it real carefully, and I didn't see anything about a PRV. Do you have a pressure regulating valve as Shacko asked about, either at the meter or where the water enters the house? It is supposed to stop surges and maintain a constant water pressure.

Yes there are first you can not use a watts 100xl it must be a watts 40 xl also where its piped in to the tank. if it goes through a tee than it must be one with an extra long prob.
What is the street pressure ?? what is the working press?? Is your water hotter than lastweek ??

asm660

Thanks for your replies....we do have a pressure regulating valve on the inlet-I have not adjusted it.I may back it off just a bit once I get a pressure gauge and check the incoming water pressure, and I will drain the expansion tank. Ist T&P lasted 7 years-next one 3 weeks-what are the chances?:)

drain the expansion tank. ?????? How do you do that????

unscrewed it......emptied it out! Thanks for the replies-esp. checking pressure-150 PSI! When that main went on-I'm lucky it didn't blow all the seals. Could only back it off to 110 from the pressure regulater valve-still better than what it was! The expansion tank and T&P are now replaced-with the pressure regulator valve next on the to do list!

the tank you emtyed should be an extrol tank most of them are white with an air vale at the other end. now that tank you can not emty when good. remove tank agan this time drop i long handel screw driver into it do not force it in if it goes in about 4" tank should be good if it goes all the way in tank is bad. (tank should not be an amtrol # 18,15 or 30 should be some thing like amtrol st 5 ,or 12 ) with the tank off use a tire gage and check the pressure that pressure should mach your house pressure if not use a bycle pump to adj pressure .

http://www.amtrol.com/pdf/MC4090%2006_09%20TXT%20Brochure.pdf
Asm660 Wiliam

Thanks again...the expansion tank was not working! It emptied out easily, the bladder was not functional....I'm afraid with the water pressure at about 115PSI-I'm going to blow the expansion tank out again, then the T&P valve too! Pressure Regulator Valve doesn't seem to be functioning...can only get it down to that 115 (from 150). May back off a bit from the main shut-off, which is right in front of it, and see if that works...the PRV is hard to get to-looks old (at least 15 years) and has lots of soldered joints with no clearance-need to get the flux and soldering gun out-haven't used it it years!

Soldering gun won't cut it for pipe...gonna need a torch (I'd recommend a MAPP gas torch).

Personally, I'd call your water supplier...never heard of 150 psi supply, thats crazy extreme.

They may have a bad regulator somewhere on their side. Don't mess with the meter if it has some sort of built in regulator..thats theirs. And don't try to throttle it with the street cut-off, won't really help the static pressure, will reduce your flow, and can damage the valve over time.

150psi input is about the max for many residential PRVs. If its old or worn, very likely it can't handle it.

Need to get this fixed ASAP, you could blow pipes, joints, toilet supply lines, etc, etc.

You'd be amazed how much water will spray out of a toilet cutoff valve when the supply line lets go and it isn't found very quickly....and thats at more normal pressures of 40-60 psi.

Water damage can make your life miserable for a long time.

Thanks for the tip about the not messing with the supply side-didn't think it was going to be that easy! I'll call the water company again-they suggested turning down the pressure with the PRV.......which was marginal, at best-maybe they are pumping it in at a high force....I never checked it before they did the work on the main a few days ago...it seems odd that the home stood there with 150 PSI for 10+ years with no damage!
PS: the PRV is connected to copper pipe both sides...not iron.

When you call (soon I hope) ask them what pressure they normally run. If they say 100..then theres a problem on their side or your gauge is wayyy off.

No Plumber...but I just never heard of it that high...100-115 yes...but 150?

And I'm not sure what the PS was intended for? I never thought you had iron pipe since you said soldered joints...
I meant no way a gun will solder water pipe. You need a propane or MAPP torch.

Almost any regulator on a house will have an adjustment range of about 25 to 75. If the pressure is higher than that, the diaphragm is shot. It cannot be adjusted down. Replace the valve.

[QUOTE=Matty2tan;1614920]Thanks for the tip about the not messing with the supply side-didn't think it was going to be that easy! I'll call the water company again-they suggested turning down the pressure with the PRV.......which was marginal, at best-maybe they are pumping it in at a high force....I never checked it before they did the work on the main a few days ago...it seems odd that the home stood there with 150 PSI for 10+ years with no damage!
PS: the PRV is connected to copper pipe both sides...not iron.

All municipal water systems are not constant, they go through ups and downs depending on how much water is being used. Any time the utility is working on the lines there may be a change in the pressure.

If they were running 150lbs all these years your T&P valve would have been blowing off every day.

You have to get your excess pressure fixed, your T&P valve will keep blowing off and you will be replacing it for no reason.

If you have a bladder type expansion tank and the bladder is not functional the tank isn't any good, there is nothing that you can blow out with that type of tank. You need to get your system fixed ASAP. :eek:

I called, after reading these posts-they tried to blow me off...but I finally got them to schedule a check of the pressure coming into the house...if it's supposed to be 60-80-how the h*** could I be measuring it at 150? And the PRV only brought that down about 30....Makes sense that it couldn't have been at that high level for years...I'd have known about it by the floods and leaky seals long before...maybe turning on that main (box itself is about 20 years old!) blew out the PRV, expansion tank, and T&P!
PS: gunguy45...I don't know what I was saying...didn't mean soldering gun...shows how long it's been since I sweated a fitting!

Your incomming pressure has nothing to due with what you have in the house, if it is over 80lb. it's up to you to reduce it not the water department. I think your inability to reduce it could be because your PRV is defective or it's not rated high enough; check the numbers on it, they should be a incomming pressure of at least 150lb., if it's less it will not handle the pressure comming in, would have to be replaced. :confused:

shacko...yer probably a lot more experienced than I...but 150 psi from the supplier? That's acceptable? Never heard or seen such a thing...esp when the supplier themselves said it should be 60-80. I presume its much higher on their mains..then reduced somehow on feeders to neighborhoods?

I would think there would be some sort of standard...but 150 is almost double the more common numbers isn't it?

With high incoming water pressure of the kind you describe, you need a pressure reducing valve to cut the water pressure and a functioning expansion tank as well.

And then you need to check your water pressure yearly or thereabouts. It's not unusual for PRV's to seize up and quit reducing the water pressure after a period of years of use.

Personally I'd get a water pressure gauge and leave it screwed on the water heater hose bib. just turn on the valve at the water heater to check the pressure.

You can get a pressure gauge that screws on to a hose bib at most hardware stores or plumbing supply stores for about $10.

shacko...yer probably a lot more experienced than I...but 150 psi from the supplier? That's acceptable? Never heard or seen such a thing...esp when the supplier themselves said it should be 60-80. I presume its much higher on their mains..then reduced somehow on feeders to neighborhoods?

I would think there would be some sort of standard...but 150 is almost double the more common numbers isn't it?

I think that the OP is mis-understanding what the supplier is saying, they are telling him that his pressure should be 60-80lbs inside the dwelling, thats a standard recommended range for inside of a house; the water supplier already told him to adjust it down with his PRV if it's over 80lbs.

150lbs. incomming pressure can occur fairly often when there is work being done on the system. There is probably a standard but water pressure is always in a state of flux due to demand; it will spike. :)

Ahhh ok clearer now, understanding is penetrating my skull..thx shack