Pressure valve water heat drips sometimes

slackercruster · November 8, 2016

When my tank is full and I heat to high temp the pressure valves drips some until I run the water then drip stops.Is this normal?

Thanks

ronmon · November 8, 2016

I think what you describe is the normal, intended function of the pressure valve. Opens to releive pressure & closes when it's done it's job.

Ron

mptjelgin · November 8, 2016

You have probably lost the air bubble that is supposed to exist at the top of the water heater. This allows for some expansion to take place as the water heats up and generally will keep the pressure valve from dripping.

To restore it, disconnect you water hose and empty it, along with any filter you may have installed. Then reconnect it, and turn the spigot back on. Go into the RV and run only the hot water. The air in the hose/filter will go into the water heater and restore the bubble. You may want to do this a couple of times, until you get air sputtering out of the faucet when you run the hot water. If this happens you'll know that you've trapped the maximum amount of air.

If you stay in place for a period of time the air will get absorbed into the water, and the drip may happen again.

If we are travelling, just connecting the empty hose/filter and running the hot water first is enough to keep to air bubble in place. It is sitting for a long period of time, or purging the air out of the hose before hooking up that creates the issue.

Jimalberta · November 8, 2016

Or you could open your PRV and drain about a quart or 2 of water out of your hot watertank. Then use as you normally do.

SCClockDr · November 9, 2016

Any small accumulator/expansion tank will solve this issue. Water as a liquid will not compress. So if it is heated with no air pocket the pressure will rise dramatically and lift the relief.

travelinbob · November 9, 2016

All I do is turn off the water supply and open hot water faucet until water stops. turn off faucet. Turn on water supply.

Devilishjim · November 9, 2016

When my tank is full and I heat to high temp the pressure valves drips some until I run the water then drip stops.Is this normal?

Thanks

I wonder how many of the above do these fixes in a stix n brics ?

1 is your water getting to hot and exceeding the pop off valve ?

2 Is there a speck of calcium or other under seat of pressure valve ?

3 Is your pressure valve in need of replacing ?

Flip the pop off lever up and flush the valve for a bit...Is it still leaking ? If so replace the pressure valve did it stop leaking ? If not your water is getting to hot in which case you replace the thermostat.

The myth about an air pocket is just that, If your pressure is high enough to push water out then it will also push the air out , You just cant see the leak but eventually you will run out of air and then comes your water leak again. But if you want to keep everybody happy then by all means put an air bubble in the top !

Pat & Pete · November 9, 2016

When I'm done flushing the water heater , I simply flip the pressure valve open until water runs out . Then flip it closed . Done .

mptjelgin · November 9, 2016

The myth about an air pocket is just that, If your pressure is high enough to push water out then it will also push the air out , You just cant see the leak but eventually you will run out of air and then comes your water leak again. But if you want to keep everybody happy then by all means put an air bubble in the top !

I disagree. Water expands as it heats. The cushion of air acts as an expansion chamber, and the increase in volume is accommodated with a modest increase in pressure. If there is no expansion chamber the pressures will rise dramatically as the water is heated, and the pressure valve will open. So you can get vastly different pressure with and without the air pocket.

When the air pocket dissipates I get a obvious surge of water when I open the hot water faucet as the extra pressure is released.

Kirk W · November 9, 2016

You have probably lost the air bubble that is supposed to exist at the top of the water heater. This allows for some expansion to take place as the water heats up and generally will keep the pressure valve from dripping.

To restore it, disconnect you water hose and empty it, along with any filter you may have installed. Then reconnect it, and turn the spigot back on. Go into the RV and run only the hot water. The air in the hose/filter will go into the water heater and restore the bubble. You may want to do this a couple of times, until you get air sputtering out of the faucet when you run the hot water. If this happens you'll know that you've trapped the maximum amount of air.

If you stay in place for a period of time the air will get absorbed into the water, and the drip may happen again.

If we are travelling, just connecting the empty hose/filter and running the hot water first is enough to keep to air bubble in place. It is sitting for a long period of time, or purging the air out of the hose before hooking up that creates the issue.

Or you could open your PRV and drain about a quart or 2 of water out of your hot watertank. Then use as you normally do.

Either one will work and both are true. I have done it both ways but when sitting still for a long term air can be absorbed into the water and it then will go away. To re-establish it without disconnecting, just turn the water off and do as Jim suggests.

The myth about an air pocket is just that, If your pressure is high enough to push water out then it will also push the air out ,

Not true since the discharge from the water heater tank is below the level that is supposed to be filled with air. The same is true of the pressure relief valve is also below the top for the same reason. If you do not have such a bubble, the relief then drips to prevent the extreme pressures and the dangerous condition that could cause.

mscans · November 9, 2016

Any small accumulator/expansion tank will solve this issue. Water as a liquid will not compress. So if it is heated with no air pocket the pressure will rise dramatically and lift the relief.

Exactly. A small accumulator installed near the inlet for the water heater will stop the over pressurization of the heater. It will also reduce the rapid start/stop of the water pump under normal and low flow conditions, such as when the spigot is only opened a small amount.

Clay L · November 9, 2016

The following is from the Atwood owners guide.

"To replace the air pocket start by turning off the water

heater, shut off the incoming water supply

and open the closest hot water faucet. Pull the

handle on the pressure-temperature relief valve

straight out to allow the water to flow from the top

part of the tank. Once the water has stopped

flowing allow the handle on the valve to snap shut,

close the faucet and re-engage the water supply. "

mscans · November 10, 2016

Depending on the relative position of the water heater to the hot water faucet the water may not flow out of the faucet (water can't flow uphill). A temporary fix is to open the drain plug on the heater or remove the anode rod and then open the T & P valve to allow the water to run out. ONLY DO THIS ONCE THE HEATER HAS COOLED. Afer the water stops, reinstall the plug/anode rod and refill the tank as usual, only then turn the heater back on.

A more permanent fix is the installation of the accumulator tank as mentioned above. Any size will do but one with a couple of gallons capacity will also solve pump short cycling.

One of these https://www.amazon.com/s/ref=nb_sb_noss_1/160-0271302-1199238?url=search-alias%3Daps&field-keywords=accumulator+tank will do the trick.

Kirk W · November 10, 2016

Exactly. A small accumulator installed near the inlet for the water heater will stop the over pressurization of the heater. It will also reduce the rapid start/stop of the water pump under normal and low flow conditions, such as when the spigot is only opened a small amount.

If the water heater has the check valve on the outlet line rather than inlet, the accumulator will solve that issue when located anywhere in the cold water system. I did that same thing with our motorhome, locating the accumulator next to the water pump and tank with it connected to the pump outlet.

ncrowley · November 11, 2016

I do not know how old your hot water heater is, but I have a 2004 that was leaking. I tried everything in these threads and sometimes it would work for a while and then come back. I got to where it would leak at least some of every trip. I finally replaced it and no leaks. It was not expensive to purchase and easy to replace.

Kirk W · November 11, 2016

I do not know how old your hot water heater is, but I have a 2004 that was leaking. I tried everything in these threads and sometimes it would work for a while and then come back. I got to where it would leak at least some of every trip. I finally replaced it and no leaks. It was not expensive to purchase and easy to replace.

Good point. Relief valves do sometimes fail and can be replaced. If you look at the disc around the relief plunger it will tell you what is needed to replace it. They are available from most home supple stores like Lowe's. If restoring the air bubble in the top doesn't solve the problem, it may well be the valve. You should open that valve each time that you drain the water heater and then when you close it, allow it to snap shut to be sure of a good seating.

slackercruster · November 13, 2016

You have probably lost the air bubble that is supposed to exist at the top of the water heater. This allows for some expansion to take place as the water heats up and generally will keep the pressure valve from dripping.

To restore it, disconnect you water hose and empty it, along with any filter you may have installed. Then reconnect it, and turn the spigot back on. Go into the RV and run only the hot water. The air in the hose/filter will go into the water heater and restore the bubble. You may want to do this a couple of times, until you get air sputtering out of the faucet when you run the hot water. If this happens you'll know that you've trapped the maximum amount of air.

If you stay in place for a period of time the air will get absorbed into the water, and the drip may happen again.

If we are travelling, just connecting the empty hose/filter and running the hot water first is enough to keep to air bubble in place. It is sitting for a long period of time, or purging the air out of the hose before hooking up that creates the issue.

I usually drain the tank after each trip. Yes, I try to get rid of the air by filling up all the tanks as much as I can. I only have a small water tank. So maybe the air cushion is the cause.