Gas Water Heater Blow-off valve leak

Folks,

The blowoff valve on our 9 year old water heater started leaking about 4 weeks ago. The valve was new with the water heater.

I replaced it with a new valve: The new valve started leaking the same day. The heater is leaking about 1 gallon per day.

I bled the system of air thru the new valve. I still need to bleed the heater thru the lower valve.

I checked the water pressure today: 70 psi. As best I can tell the system does not have a pressure expansion tank.

The heater tank appears to be fine.

Does anyone have any suggestions for what I should do next?

Thanks,

Rog

First of all, you don't have to bleed the system. It does that automatically when the tank fills. It does sound like you have an expansion problem, but if you don't have a pressure regulator and the system has been functioning OK in the past, it does seem a bit strange that it would suddenly start tripping the TP valve now. 70 psi is a bit high so you could probably justify a PRV and expansion tank. I'd cut the pressure down to around 50 psi as a starting point. You can always raise or lower the pressure if you want to.

Check the pressure, then run a lot of hot water so the heater kicks on. Watch the pressure gauge over the next 20 to 30 minutes to see if it goes up over a hundred

Is there a Pressure Reducing Valve and / or check valve installed on your system?

It may be outside in the meter pit.

Water Temperature

Also be sure the water heater is not overheating. This is a temperature and pressure relief valve and if the thermostat is malfunctioning it could be overheating until the relief valve opens and cold water is added to the tank.

T&p

If it were an overheating condition, it would discharge much more than a gallon of water. But until you know why it is leaking, there is no way to cure it.

Water heater blow off valve leaking

Folks,

So yeah, this problem has not been at the top of the list....

Anyway....

I took the good advice of Jimbo: Run the water fast from 2 faucets for 3 to 4 minutes, then shut off the faucets. The pressure routinely spikes to 150 psi or more. At full flow the gage reads about 40 psi. Static pressure with minimal flow is 70 psi.

The system has a Watts type 5 PRV. It has "714" stamped on the side. "ASSE std 1003" molded in the same side. The valve is about 35 years old. Watts has a website, I haven't been able to idenitify this valve in their data sheets.

Question: is it worth trying to adjust it? Is there a service kit for something this old? I am guessing that replacement is the right path. What is a good quality valve to replace this with?

I cannot find an expansion tank. This house was totally built on the cheap, so I would guess it was omitted.

Looks like this is an addon for me.

BTW: We get our water from a reservoir 2000 feet higher than the house, so high pressures are SOP. (Boulder CO)

I put a lawn irrigation system in about 18 months ago. Other than the higher flow demands thru the valve, my guess is that this is independent of this problem.

TIA for the help.

Rog Smith

You need to install a potable water expansion tank. The physical location of the tank can be anywhere you desire. Preferably with the threaded connector of the tank facing upwards. The line to the expansion tank should tee into the cold supply to the water heater between the shut off valve and the water heater.

The pressure spike at 150 psi when? does it start at 70 then slowy raise to 150 till you open a faucet? if so then i would agree put in an expansion tank. I think you can get one at Mcgucken or the home depot over there. If it spikes at night then i would say the PRV is bad.

You would run cold water while the water heater is not heating to determine if the PRV is working properly. In any case with the PRV you will need a expansion tank. Run the water the pressure will drop down and stay low. if it creeps back up the PRV is bad.

Prv

The fact that the pressure drops when he opens a faucet automatically means it is bad.

Water Heater blowoff valve

Folks,

Thanks again for all the help.

I replaced the Pressure reduction valve this weekend with a new Watts valve.

Like magic, the Water heater valve is not leaking...(Go figure)

The Watts valve is factory set at 50 psi, I am seeing 35 to 60 psi at a laundry tap near the water heater. Water flow/velocity at the upstairs shower appears to be lower, but OK. The sprinkler system appears to flow adequate water. (Dusted if off this AM)

I did not have time to install the pressure expansion tank in the water heater circuit this weekend.

One small concern: I have a (Very) small leak at the inlet side of the PRV. When it first occurred, I disconnected the valve and changed the sealant from white Teflon tape to yellow tape. That change reduced the leakage from a drop every 5 to 10 minutes, to a drop every 20 minutes or so.

Question: will the teflon tape "flow" and seal up this leak? What other sealant might work better? All ideas/suggestions are appreciated.

Thanks again for all the advice/assistance.

Rog Smith

I use teflon tape then coat it with teflon paste such as megaloc. I know it's like belt and suspenders but I don't get leaks!

Folks,

THanks again for the help.

I fixed the leak with PTFE tape and dope.

I installed the Pressure gage on the cold water line.

It routinely peaks at 100 psi. The new PRV was factory set at 50 psi.

Is the 100 psi peak an expected situation? Do I have a problem?

I am not seeing any seepage/leaks at any of the faucets/valves. The sprinkler system works fine.

Thanks,

Rog

Try backing the adjusting screw out and see if that lowers it. If it doesn't the PRV is not working right.

If it is installed right and the water heater is not heating and the pressure is 100 PSI then the valve is bad. The union is the inlet side and an O ring is used for sealing the union and preventing leaks. If the valve is lined up right no Teflon or dope should be needed, and when used it only allows you to tighten the union more.