Hot water heater expansion tank psi?
- Thread starter softtouch
- Start date
Sneakers
Just sneakin' around....
The pressure in the expansion tank will rise and fall based on the pressure in the line. It's purpose isn't to regulate the line pressure or to reflect the actual line pressure, but to provide a place for pressure to go when the hot water heater heats and expands. 40psi is just the static pressure recommendation by the manufacturer.
Sneakers
Just sneakin' around....
The water is only cold the first time you start it up. From that point forward, yes, you're heating water that is already hot.
What?..you new?
Clem72
Well-Known Member
You should get a pressure gauge and check at the lowest level. Usually you can get away with one that connects to your outside garden hose spiget.
Ideally you would match the pressure as close as possible to the psi you read, it should be less than your water heater pressure relief setting.
If you set it too low it will instantly compress and won't be of any help when you have a water pressure surge. Set too high and you have the opposite issue that you cant compress the bladder at all and it's not useful.
My water pressure fluctuates between 40 and 50 on a regular basis and I was getting occasional (a couple times a month) releases from the pressure valve on my water heater. I put in the tank and set it to 55 and haven't had an issue in 5 years or so.
Clem72
Well-Known Member
The bladder needs to be higher than your water pressure otherwise it will at least partially fill and will be less useful or not useful at all.
black dog
Free America
Wrong, it should be set to the homes average high water pressure.
Kinnakeet
Well-Known Member
I think your keeping it hot
Clem72
Well-Known Member
For the reading impaired I said in my immediately previous post that it should be SET as close as possible to the highest read pressure from the lowest spigot in the house. So just repeating what I said doesn't make you smart.
My second post was about how the bladder functions not what to set it at, as that was addressed in my previous post. This post was in direct response to the person saying they would leave it at 40, which is likely to be too low. The bladder is only effective if it is fully inflated under normal circumstances and it will only remain fully inflated if it's equal or higher than the normal water pressure.
The Dog is a pretty smart feller though...just sayin'...
LightRoasted
If I may ...
For your consideration ...
How much pressure should be in a water heater expansion tank?
Regardless of the size, Federal Department of Transportation regulations limit the air charge in a thermal expansion tank to 40 psi for shipping.
Expansion tanks are pre-charged to about 40 PSI, but the pressure must be adjusted based on the home’s water pressure. The recommended water pressure is between 50 and 60 PSI. Thermal Expansion Tanks contain an air bladder which is pressurized with air, and expands and contracts to absorb the expanded water from the water heater. Check the air pressure in the Expansion Tank using a tire gauge. If the inlet water pressure is higher than 40 PSI, the expansion tank's air pressure must be adjusted to match that pressure but must not be higher than 80 PSI.
To raise the pressure inside a water heater expansion tank, you will need a small tire hand pump. Ensure that you do not use a motorized pump, as it may increase the pressure too rapidly, causing the bladder to rupture. Pump small amounts of air into the tank at a time. Measure frequently to ensure the pressure does not rise above the desired PSI and stop immediately once the appropriate pressure is reached.
How much pressure should be in a water heater expansion tank?
Regardless of the size, Federal Department of Transportation regulations limit the air charge in a thermal expansion tank to 40 psi for shipping.
Expansion tanks are pre-charged to about 40 PSI, but the pressure must be adjusted based on the home’s water pressure. The recommended water pressure is between 50 and 60 PSI. Thermal Expansion Tanks contain an air bladder which is pressurized with air, and expands and contracts to absorb the expanded water from the water heater. Check the air pressure in the Expansion Tank using a tire gauge. If the inlet water pressure is higher than 40 PSI, the expansion tank's air pressure must be adjusted to match that pressure but must not be higher than 80 PSI.
To raise the pressure inside a water heater expansion tank, you will need a small tire hand pump. Ensure that you do not use a motorized pump, as it may increase the pressure too rapidly, causing the bladder to rupture. Pump small amounts of air into the tank at a time. Measure frequently to ensure the pressure does not rise above the desired PSI and stop immediately once the appropriate pressure is reached.
glhs837
Power with Control
Becuase hot water heat keeper sounds silly.
When I worked plumbing, would tell customers that is against Federal Regulations to sell a hot water heater. 
I have installed a water pressure gauge on the laundry tub spigot in the basement. It is 3' 6" lower than the outdoor hose spigot and 5' 3" lower than the expansion tank. It is showing 48 psi. I will check it over a few days to see if it changes.
I installed this Water Ace Pump Company 5 gallon tank 20 years ago when the water company installed anti backflow check valves.
The instructions that came with it don't say anything about adjusting the air pressure to match the water pressure.
I had a 82 gallon water heater at that time. It has since been replaced with a 52 gallon heater.
I installed this Water Ace Pump Company 5 gallon tank 20 years ago when the water company installed anti backflow check valves.
The instructions that came with it don't say anything about adjusting the air pressure to match the water pressure.
I had a 82 gallon water heater at that time. It has since been replaced with a 52 gallon heater.
...or, hot water tank.
black dog
Free America
Thank you,
One of us has taken that big test that WSSC gives for plumbers, along with dozens of manufacturers classes.
One of us has installed a few thousand backflows and hundreds of water heaters and bladder tanks. Some Southern Md counties require them when Installing new water heaters on city water, Calvert was one when I was living in St Marys.
The other has not.