Too Much Pressure in Water Heater?

[WorthFlorida]

sorry no entry here. Trying an Apple Pencil for the first time.

 

[Disney1984]

I changed out the expansion tank about 3 weeks ago and everything is working perfectly now. The T & P valve is no longer releasing water and the internal water heater pressure doesn't go much higher than the incoming water pressure. The old expansion tank was completely full of water. I'm not a professional plumber and couldn't have done it without everyone's assistance! Thank you so much for your help!

 

[Sponsor]

 

[Thekid1]

I changed out the expansion tank about 3 weeks ago and everything is working perfectly now. The T & P valve is no longer releasing water and the internal water heater pressure doesn't go much higher than the incoming water pressure. The old expansion tank was completely full of water. I'm not a professional plumber and couldn't have done it without everyone's assistance! Thank you so much for your help!

Sounds good. I came too late, but I had the exact same problem as you and it was the expansion tank and I was going to recommend pumping air into it to match your street pressure like you did. I also find that a good way to check the expansion tank is to flick it with your fingernail and listen to the sound on both sides of the diaphragm. One side should sound solid(filled with water), and the other side should sound hollow.......if in good working order.

One other thing I would do is install a ball valve on the line that feeds the expansion tank so that you can simply shut it off and throw a new one in without touching anything else. I'm sure some people wouldn't like that idea here, but for your own house, why not? I do the same on my boiler expansion tank and also I do it on the air scoop vent with a ¼" valve.

........now if I could only get a recommendation on my thread lol.

 

[Cracked]

I have a 50 Gallon State water heater attached to hydronic heating system in my home attic. I had the water heater professionally installed by a plumber about 5 years ago. The unit had a problem with the 150 PSI tp valve blowing immediately after the installation. The plumber was frustrated and confused at why it was blowing. He added an expansion tank just to be safe. He also installed another new tp valve and its worked fine for 5 years. About six months ago I noticed the tp valve blowing again. I've had a couple of plumbers come out and they can't figure out what the problem is. They checked the expansion tank and it isn't full of water and appears to be OK. I performed my own investigation. Water pressure at a hose bib outside of the house is a constant 60-65 PSI. I placed a pressure gauge on the water heater at the drain bib as well. I discovered that pressure at the water heater bib would reach 140 PSI towards the end of the water being heated after someone took a shower right before the burner would kick down. The 140 PSI slowly drops after the burner turns down. The PSI at the outside hose bib remained a constant 60-65 PSI. The tp valve starts leaking a small, but steady stream at 140 PSI. It's obvious to me that the tp valve is bad because it shouldn't blow until 150 PSI, but I'm being told the internal pressure of the water heater should never get that high. I called the Tech line at State Water Heaters and told them of my problem. The temperature setting on the water heater isn't to hot and is set at 120 degrees. It was at 125 degrees. State says the internal pressure of the water heater shouldn't get over 80 PSI. The pressure gets to 140 PSI without the hydronic house heater being on. The weird thing is the water heater pressure recently stopped jumping to 140 PSI and stayed at 65-70 PSI through the heating cycle. It was fine for a about 3 weeks and the problem has started up again. Should the internal pressure of the water heater get up to 140 PSI? The manufacturer says no. Does anyone have any idea what could be going on here?

Disney1984, not sure how I happened across your questioning post. If the problem was not discovered it sounds to me like a simple pressure calibration issue. Translation - I’d be willing to bet that your hot water heater was never fully heated at desired temp setting while no hot side fitting was connected to the hot-out port —no check valve nipple, no T&P valve, nothing. Not surprised your expansion was full. You’ll get way more gentle life out of your expansion tank and pipes if you pressure calibrate all your hot lines with the next expansion tank change. Or heater calibration first, then calibrate hot fixtures lines, which is a little different process.

To Pressure Calibrate H2O Heater: have the heater water filled. While it’s heating up, be sure to have the UPPER MOST PORT OPEN TO AIR in order to disallow pressure build up in the tank. Steam and hot water will come out of the open vent/port while it heats so have a way to capture the hot water for discard. Personally, I use an open ball valve and short clear tubing to drain the heated h2o (expanded) into a bucket on the floor after annually draining the tank of any sediment. Check back in 30-60 minutes. Once the heater stops heating the water is when you can connect the heater back into service to supply your home. Your hot water tank is now calibrated / zeroed at its safe, maximum allowable hot h2o volume. With heating up the water, approximately 2 cups of hot water & steam was drained via the top with no air bubble.

HOT OUT Connections. 1ST open (always keep open (you will likely need pliers to position the top silver tab vertically-open) your T&P valve to always drain your tank to its dedicated drain unhindered when the heated h2o’s expansion exceeds the tank. Frankly, so long as you do that you will never need a T&P valve. Don’t forget to have a p-/bottle trap in that drain line. Think of your water heater as a range top kettle used for hot beverage water instead of another source, it has a steam vent for safe hot water expansion, not to pressurize, no pressure gauge!

Assuming you use the dielectric check valve nipple as the first hot-out fitting makes your expansion tank for the expanded hot h2o in the piping for your hot h2o fixtures. No water heater and its hot-line fixtures should ever be setup as though it’s a pressure cooker! You should get more life out of your expansion tank also.

For you, hopefully, this is better late than never.

I have a 50 Gallon State water heater attached to hydronic heating system in my home attic. I had the water heater professionally installed by a plumber about 5 years ago. The unit had a problem with the 150 PSI tp valve blowing immediately after the installation. The plumber was frustrated and confused at why it was blowing. He added an expansion tank just to be safe. He also installed another new tp valve and its worked fine for 5 years. About six months ago I noticed the tp valve blowing again. I've had a couple of plumbers come out and they can't figure out what the problem is. They checked the expansion tank and it isn't full of water and appears to be OK. I performed my own investigation. Water pressure at a hose bib outside of the house is a constant 60-65 PSI. I placed a pressure gauge on the water heater at the drain bib as well. I discovered that pressure at the water heater bib would reach 140 PSI towards the end of the water being heated after someone took a shower right before the burner would kick down. The 140 PSI slowly drops after the burner turns down. The PSI at the outside hose bib remained a constant 60-65 PSI. The tp valve starts leaking a small, but steady stream at 140 PSI. It's obvious to me that the tp valve is bad because it shouldn't blow until 150 PSI, but I'm being told the internal pressure of the water heater should never get that high. I called the Tech line at State Water Heaters and told them of my problem. The temperature setting on the water heater isn't to hot and is set at 120 degrees. It was at 125 degrees. State says the internal pressure of the water heater shouldn't get over 80 PSI. The pressure gets to 140 PSI without the hydronic house heater being on. The weird thing is the water heater pressure recently stopped jumping to 140 PSI and stayed at 65-70 PSI through the heating cycle. It was fine for a about 3 weeks and the problem has started up again. Should the internal pressure of the water heater get up to 140 PSI? The manufacturer says no. Does anyone have any idea what could be going on here?

Did you ever find the problem?

 

[davnit32]

No, the pressure inside the water heater should not reach 140 PSI. If your house pressure stays at 60–65 PSI, this strongly suggests a thermal expansion issue. The expansion tank may be undersized, failing, or not properly charged. I would check the air pre-charge of the expansion tank and verify it matches the incoming water pressure. Also, make sure there is no check valve or pressure-reducing valve trapping pressure in the system. Replacing the expansion tank or adding a second one may solve the problem.

 

[Fitter30]

Disney1984, not sure how I happened across your questioning post. If the problem was not discovered it sounds to me like a simple pressure calibration issue. Translation - I’d be willing to bet that your hot water heater was never fully heated at desired temp setting while no hot side fitting was connected to the hot-out port —no check valve nipple, no T&P valve, nothing. Not surprised your expansion was full. You’ll get way more gentle life out of your expansion tank and pipes if you pressure calibrate all your hot lines with the next expansion tank change. Or heater calibration first, then calibrate hot fixtures lines, which is a little different process.

To Pressure Calibrate H2O Heater: have the heater water filled. While it’s heating up, be sure to have the UPPER MOST PORT OPEN TO AIR in order to disallow pressure build up in the tank. Steam and hot water will come out of the open vent/port while it heats so have a way to capture the hot water for discard. Personally, I use an open ball valve and short clear tubing to drain the heated h2o (expanded) into a bucket on the floor after annually draining the tank of any sediment. Check back in 30-60 minutes. Once the heater stops heating the water is when you can connect the heater back into service to supply your home. Your hot water tank is now calibrated / zeroed at its safe, maximum allowable hot h2o volume. With heating up the water, approximately 2 cups of hot water & steam was drained via the top with no air bubble.

HOT OUT Connections. 1ST open (always keep open (you will likely need pliers to position the top silver tab vertically-open) your T&P valve to always drain your tank to its dedicated drain unhindered when the heated h2o’s expansion exceeds the tank. Frankly, so long as you do that you will never need a T&P valve. Don’t forget to have a p-/bottle trap in that drain line. Think of your water heater as a range top kettle used for hot beverage water instead of another source, it has a steam vent for safe hot water expansion, not to pressurize, no pressure gauge!

Assuming you use the dielectric check valve nipple as the first hot-out fitting makes your expansion tank for the expanded hot h2o in the piping for your hot h2o fixtures. No water heater and its hot-line fixtures should ever be setup as though it’s a pressure cooker! You should get more life out of your expansion tank also.

For you, hopefully, this is better late than never.


Did you ever find the problem?

Steam doesn't come out of a heater not by a long shot. To produce steam the water temp has to be 212° f. Residential tank hydro tested at 300psi working 150 psi what the relief is set or 210°. Steam expands 1600 times and there isn't a relief valve made that can control that expansion. Boiler and water heaters explode from running out of water with burner still firing. Water enters the red hot tank flashes into steam and the expansion explodes the tank. 40 gallon heater 100° temperature rise =.9 gallon (60°- 160°) 25-30 lb increase in pressure.