Water Leaking From Pressure Valve

nycpa

Hi, While changing my steam boiler water, I noticed the floor a little wet next to the water heater.  There was a drop of water at the end of the pipe that's connected to the pressure valve.  I opened the valve and brown water came out.  Now, it seems to have more drops coming from the pipe.  I have a gas A O Smith water heater.  It's only 1.5 years old.  Do you guys think its the pressure valve that needs to be changed or the actual water heater itself.  I attached a picture.  Will A O Smith send some one over to replace it if I put a warranty claim on it.  Also, why would a heater only 1.5 year old start to leak?  Thanks for the replies.    

Ironman

Are You...

On a municipal water supply? If so, your incoming pressure from the street could be 100psi or more. A fast closing valve in your washer or dish washer can cause a water hammer that will cause the relief to drip. If any of the above are correct, then you should have a pressure reducing valve on your incoming line set to 60 - 70psi.max, an expansion tank on your water heater and water hammer arrestors on both hot and cold at your washers.



The relief valve can be replaced very easily without the water heater needing replacement. The manufacturer will not provide labor; you'll have to contact your contractor.



Also, If you're on well water, have your well tank checked. It may be water-logged.

nycpa

Water Pressure

Yes I am on a municipal water line.  With my old water heater, I never seemed to have this problem.  I do have a washer and dish washer.  When you say have a pressure lowing device, did you mean attaching it to the main water line that comes into the house?  Wouldn't  that lower the pressure on the entire house supply?  Can I lower the pressure just on the water heater?  And, how do i measure pressure coming in?  Also, can I buy all these items from my local plumbing supply store?  I can have my plumber install these, (he's not that good at technical things such as diagnosis of problems).



Also, when you say attaching a water hammer arrestor on the washer, do you mean the dish washer and washing machine of on the hot and cold valves on the water heater itself?

billtwocase

relief valve

generally once they are opened, they will rarely seat again. Have it replaced, and you may need a thermal expansion tank installed. If you already have one, have it checked, It may have lost it's charge

Ironman

Some Answers

The PRV should be installed on the incoming line from the street. The pressure should not be above 60 - 70psi on anything in your house. Simply installing a pressure gauge will tell you what your water pressure is. You can make a setup with a gauge and a couple of fittings that would attach to a house bib to check your pressure. It may increase significantly at late night and early am when most people are sleeping and usage is low. That's the time to check it.



All of the items are standard and even required now in most municipalities. The expansion tank (a domestic one, not hydronic) goes on the cold line at the water heater. You can get arrestors that screw on at your washer's hose connections.

EricAune

1st things 1st...

The construction of these valves is, in most cases, the exact reason they start to leak.  In your case I would say after only 1.5 years this is what is happening.



The valve is made from forged brass with a machined area that provides a seating surface for a simple rubber gasket to make a [hopefully] watertight seal while a spring inside the valve pushes against it.



Water quality, thermal expansion and the simple fact that the materials that make up the valve are average quality at best are all reasons why this valve can fail.  The manufacturer recommends the valve be "exercised" annually with hopes only that this will insure its proper function when needed rather than create a situation where your heater may in fact act like a missile and blast off through your roof and land in the neighbors yard.



Your heater is not going to land in your neighbors yard, the valve is working.  In fact, like thousands of other relief valves like it, it is leaking likely because it is made in such a way and from such materials that it has failed and probably just needs replaced.  You will find a replacement valve at your local hardware or big box store, I would recommend finding a more competent plumber if for nothing more than to raise your confidence in him/her.



The question for all of us professionals has and will be for a long time "Why doesn't someone design a T&P valve that's worth a darn?!" 

nycpa

Thanks for the reply guys

One last question, is it standard practice today to install these expansion tanks on the water heater line?  I've never really seen it along side a water heater like in lowes or home depot.  Also, is the pressure relief valve adjustable to 60 to 70psi?  In order to read the pressure in my house, the pressure reader would be a permanent install by cutting the main water line and installing one.  Also, do the pressure reduction valves leak themselves?  I don't want to open a can of worms if i can avoid it.   

ABSolar

dripping pressure relief valve

Well SYE,

you may have to install the potable domestic expansion tank IF there is any type of check valve between the street supply and your hot water tank.  This IS standard procedure IF there is, because you have a heated closed loop system which needs room for thermal expansion.  In this scenario, you only allow for the water to expand by opening the tap and using water.  During a long pause between draws, water volume in the closed system  increases as the water heater does its job heating water.  Potable water expansion tanks cost more than heating system expansion tanks.  As such, I haven't seen 'em at Lowes or Home Depot. 

Because you exercised the pressure relief valve, you MAY have introduced small particulate matter that interferes with proper sealing on the valve.  These things are notorius for doing that.  You can fuss with it and MAYBE get it to seal, or you can pay the 8-10 bucks and install a replacement unit.  At least your unit did it's job and dribbled some relief for some existing condiditon.  Better than the water tank rocket through all your floors and roof. 

For measuring water pressure, you CAN buy a low cost simple thread on water pressure gauge available at the big box stores.  Either put it on the drain of the water heater, hose bib outside, or adapt it to an indoor faucet fixture.

With the water pressure gauge, you can determine if the street pressure is in fact, too high for the house.  As stated by other poster, you may have to install a pressure reducing valve after the street meter on the cold supply.