Water Heaters - TP Valve

I just replaced my TP valve after 7 years, and lowered the water temperature. The new valve is now leaking (after 2 months). This is a 40 Gallon gas unit.

What did you replace it with make and modle # please

I used a Watts 100XL 210 Deg. The one I replaced was a Cash Acme 3/4 NCLX-5.

do you have that vale in hand if so what other # are on it?? or what moddle # of unit is it hot wate unit
You have the wrong vale in it if its watts it should be a watts 40 xl but they have 6 types to chose from
William

The additional # on the old valve are SER.7

The water heater is a Bradford& White 40 Gallon Model MITW40L6EN12 with a blower on top.

I'm not sure about the new valve. I can't find your water heater on the Bradford White site for comparison. I do know that the one you've put in is a very common replacement valve.

The 40XL's are listed as a commercial valve.

Regardless, the new valve should not fail after two months. Do you have an expansion tank on your water system? More likely it is waterlogged. When the water gets hot and expands it can't go anywhere so the T&P is popping.

I do not have an expansion tank installed. I courious as to why after all these years am I having this problem?

It could be a defective valve but usually it would fail immediately, not after only a couple of months.

How bad is the leak? If you open a hot water faucet does it stop? If it does it is probably a pressure issue.

Have you turned up the water temperature lately? Does the water seem excessively hot?

Was the Cash Acme valve the original? If it was I'd head over to my nearest plumbing supply store and pick up another or have them match it exactly. Bring the model # of the water heater with you. Do not rely on the staff at the orange and blue stores to help you.

It only "blows off" once a day for the past 2 days. I reset the temp lower (120) when I replaced the original valve. What would be the highest pressure the system can tolerate?

I'm going to get a pressure guage to check it at the drain on the heater.

There should be a tag on the valve with the set pressure. It's usually 150 but could range from 75 to 150 on most of the Watt's valves. It may also appear on the ring around the top of the valve.

Is it just a "pop" or is a lot of water coming out? If a lot of water it is probably an overtemp. If it is just a pop, it is probably a pressure problem.

Do you know what your house water pressure is? You can pick up a pressure gauge at the big box stores.

The 40XL's are listed as a commercial valve. yes they are but thats what a 40 gal tank needs a 100 xl will blow off. in a 40 gal

I do not have an expansion tank installed. I courious as to why after all these years am I having this problem? [/COLOR] Did you have the water meater changed??

This also could be caused by water stacking in the tank

I just check my water pressure it is 80 PSI at the drain of the hot water tank. The replacement Watts valve 150/210. Is the water pressure to high from the city?

I checked my water pressure when the water heater was running. The pressure went up to 170 PSI and the relief valve blew off (like it is suppose to). What is the best way to reduce the pressure and also the least expensive? Can I purchase a differen TP valve?

80 at the drian from the hot water tank as you stated
thats not the street press. to get the street press ose in water hose forcet out side of your house.
ok sounds like you have a hose bib gage thats good hopfully you got one that reads at least 150 lbs more is better

now with it screwed in the the bottom drain vale of the tank Or you could even use the fitting the goes to the washer

1 open vale read gage press and note leave open
2 run hot water in tub at least 3 mins after unit comes on to reheat water. at this time you can close hot water vale in tub
3 wach press go up as water heats
--------- watch--------
if vale blowes note press.
when unit turns off note press
if vale does not leak repeat from #2 down
and post.
Wiliam

looks like you did it ok what is your street press. Beer 4U2

I just check the street pressure, it is 78 PSI.

ok well first I my self would use a watts 40 xl thats coad where i lived on a 40 gal heater
looks like you might need an
THERM-X-TROL ST-12 Expansion Tank do not use a #5 to small
if you leave things the way they they are you will need on this will go on to a tee on the cold water side best place is at the tank but it does not have to go there
William

I also have a Conbraco #37-201 vacuum relief valve (15 CFM) on the cold water inlet. What is it supposed to do? I check my water temp with a digital multimeter the temp. is 115 Deg. I have a picture, but I'm not sure how to attach.

I also have a Conbraco #37-201 vacuum relief valve (15 CFM) on the cold water inlet. What is it supposed to it vents the system if there is a vacuum meaning that if the water co. looses press it will not suck water from your tank. under vacuum tank could crack so its a safty device.
temp is fine unless the water gets really HOT

So the only remedy is to install an expansion tank?

My question is why after 7 years are we having this problem? I checked with the water department and the pressure has been the same 75-80 PSI for a long time. We have over 100 units that are starting to fail. Some people are spending $1,000 - $2,000. to have their water heaters replaced.