Hot water heater pukes

Jason_4

Maybe twice a weak after the wife takes one of those long long hot hot showers the hot water heater will let about 1/4 of a gallon of water out of the pressure release vent. After a little bit of time it stops on its own. Why? Is the pressure valve faulty? This happened once or twice last year so I bought a new pressure release valve. That seemed to solve the problem until recently, now it seems to happen more frequently (see first sentence). It's about 25 years old. It's a 30 gallon Rheem Fury. The heater is rated for 127.5 psi, the pressure release valve says 150 psi max. Is this hot water heater just at the end of its life?

Sherwin Swords

water heater

Most likely you have a back flow preventer (one way check valve) between the water heater and your incoming water line. After using most of the hot water, the heater is re heating the cold water. 30 gallons of cold water will expand by approx. one & 1/2 quarts when it's tempeature is raised 60 degrees. This extra volumn has to go some where. If no one uses water from another faucet, flushes a comode, etc. then the "relief" valve does it's job. Solution: have a "pro" plumber check to be sure this is what is happening. He will probably recommend installing an expansion tank.

Jason_4

Ok, but it never used to do this? Why now?

Floyd

If your on \"city\" water...

It's probably because they jacked the pressure up to make up for more homes being on the same size lines and therefore don't have to dig up ther lines and replace them with bigger lines.

Higher press. = less tolerance to expansion

Sherwin Swords

water heater relief

Also, water co. may changed your meter lately. Meters in our area will have back flow preventers installed. Another possibility, thermostat on water heater could be problem. If you are having times that water is much hoter than usual, that would be a clue. We have seen similar problems that you described. Some time it takes a little detective work to spot what suddenly caused the "relief" to open. The "Pro" Plumber will have the tools to check to see if the problem is with the heater, relief valve, thermostat,
or pressure build up in water system. Good luck.

hot_rod

Pick up a

"lazy hand" gauge at the plumbing supply house. Screw it onto the water heater drain valve and watch it over a day ot two. It has a second "floating needle" that will show you the pressure spikes.

You may need a PRV added and a thermal expansion tank, properly sized, on the system.

Also buy a hose cap for that water heater drain cock. They often drip after use

hot rod

Steve Paul

Puking water heaters

It is possible that after a long draw of hot water the incoming cold water will cycle the thermostat. As the thermostat cycles on and off you can have thermal stacking. That is strata or layers of hot water gradualy increasing in temperature as they get closer to the top of the tank. The relief valve is set at 210*.Because the relief valve is in the top 6" of the heater it feels the hottest water in the tank which may be substantially hotter than the 140*-160* that the thermostat is set for. Try lowering your setting by 10*-20*, if the problem stops, thermal stacking is the problem.

[Deleted User]

Who you calling a hot water heater puke...

eh??? I've been called worse. I agree with HR's assessment. It's either temeperature or pressure thats causing the "discharge". If you eliminate one, it's the other.

Make sure when you install the expansion tnak that you oversize it slightly. Too big can't hurt, too small will.

ME