hot water tank

[bertrand]

there is air pressure in the hot water tank of my 5th wheel. when the city water is not connected and I empty the water tank and even when the relief valve is open the pressure is so stong it takes the plug right out of my hand. I don't understand why this is happening, does anybody have any ideas?
Bert from Nanaimo

[Allworth]

Leave the faucet open while you open the relief valve. This will let air draw back through the system until everything comes to atmospheric.

[bertrand]

thank you Wildtoad and Old -Biscuit for your suggestions, I will try what you suggested and I also suspect that I may have a bad valve

[Old-Biscuit]

wildtoad wrote:
When you heat water in the wh it builds a lot of pressure (water expands when heated) which is why sometimes the relief valve will drip. Even if you disconnect from city water, turn off the water pump, drain the fresh water tank there is still pressure in the wh. There are several way to relieve this pressure. 1 is to simply open a hot water faucet until it quits flowing. 2 is to open the pressure relieve valve but be careful water could still be hot. Only after either of these do you want to open the drain plug.

On edit, if you still have pressure after opening the relief valve I suspect you may have a bad valve.

THIS^^^^^^^^^^^^^^^


Open a faucet Hotside...that will relieve any pressure in Hot Lines AND Water Heater

[wildtoad]

When you heat water in the wh it builds a lot of pressure (water expands when heated) which is why sometimes the relief valve will drip. Even if you disconnect from city water, turn off the water pump, drain the fresh water tank there is still pressure in the wh. There are several way to relieve this pressure. 1 is to simply open a hot water faucet until it quits flowing. 2 is to open the pressure relieve valve but be careful water could still be hot. Only after either of these do you want to open the drain plug.

On edit, if you still have pressure after opening the relief valve I suspect you may have a bad valve.

[2oldman]

I have pressure when the water is hot, but how can you have pressure with the tank empty? And when the relief is open?