Refill Water Heater

Just another idea. I clean out my heater and flush it out after each season to get all the calicum off the rod. You would be surprised of the calicum build up.

Be SURE that your heater is OFF. that is from experience. As all others posted. Open faucets including shower to relieve air pockets.

rrupert wrote:
Open the pressure relief valve while filling and that will purge the air from it, then open the faucets to purge air from the lines.

Please forgive me and allow me to backup on my words.
From the Atwood WH manual:
If the the pressure temperature relief valve drips it does not mean it is defective. It is likely from expansion of the heated water where there is no air gap inside to absorb the expansion of the water.
"To replace the air gap follow these steps:
1. Turn off main water supply( the pump or water hook up source).
2. Let water cool or let run to cool.
3. Open the hot water faucet closest to the water heater.
4. Pull handle of pressure temperature relief valve straight out and allow water to flow until it stops.
5. Allow pressure temperature relief valve to snap shut; close faucet; turn on water supply.
6. Turn on water heater and test."

"At least once a year manually operate pressure-temperature relief valve."


There is good information in the manual. We all need to review it occasionally.

Thanks Old-Biscuit. I think that is the way I'll go about it....

Old-Biscuit wrote:
You want an air pocket at top of tank....tank is designed to have an air pocket.
Water expands when heated and the air pocket is compressed to control pressure..water will not compress.

IF you have not changed any valving on backside of WH (bypassed it) then just turn water source and open the closest faucet hot side to expel air from system as water fills WH tank and plumbing system.
Depending on WH tank size (6 or 10 gallon) it will take a few minutes until water flows from hot side of faucet. Then open cold side and bleed any air out of cold side plumbing. Repeat at other faucets/shower/toilet.

The air pocket at top of tank helps keep the PRV on WH tank from dripping when water is heated.



IF you find PRV dripping then air pocket has been lost
Turn off water source
Open faucet hot side to relieve pressure
Open PRV via lever.....leave open until water stops flowing out PRV then let PRV snap close
Turn on water source
Close faucet

This is the correct way to fill the water heater in an RV for expansion purposes...

llowllms wrote:

rrupert wrote:
Open the pressure relief valve while filling and that will purge the air from it, then open the faucets to purge air from the lines.

That's the way I have done it for years and it works every time. Once the water is expelled from the relief valve the heater is safe but the faucets still need purged before turning the heater on. I always do that by starting at the furthest point and work my way back.

Me too.

rrupert wrote:
Open the pressure relief valve while filling and that will purge the air from it, then open the faucets to purge air from the lines.

That's the way I have done it for years and it works every time. Once the water is expelled from the relief valve the heater is safe but the faucets still need purged before turning the heater on. I always do that by starting at the furthest point and work my way back.

rrupert wrote:
Open the pressure relief valve while filling and that will purge the air from it, then open the faucets to purge air from the lines.

I don't think the pressure relief valve is really designed for continuous or frequent operation. Sooner or later it's not going to seal. Once in a while to make sure it's not frozen up, but not for general use...

You want an air pocket at top of tank....tank is designed to have an air pocket.
Water expands when heated and the air pocket is compressed to control pressure..water will not compress.

IF you have not changed any valving on backside of WH (bypassed it) then just turn water source and open the closest faucet hot side to expel air from system as water fills WH tank and plumbing system.
Depending on WH tank size (6 or 10 gallon) it will take a few minutes until water flows from hot side of faucet. Then open cold side and bleed any air out of cold side plumbing. Repeat at other faucets/shower/toilet.

The air pocket at top of tank helps keep the PRV on WH tank from dripping when water is heated.



IF you find PRV dripping then air pocket has been lost
Turn off water source
Open faucet hot side to relieve pressure
Open PRV via lever.....leave open until water stops flowing out PRV then let PRV snap close
Turn on water source
Close faucet

Open the pressure relief valve while filling and that will purge the air from it, then open the faucets to purge air from the lines.