how does water get to the hot water heater when you drain it

2oldman wrote:

Old-Biscuit wrote:
Over time the air pocket can be absorbed into water........then you will need to re-establish the air pocket

How would you know that?

Rest of quote.....
"or pressure will increase due to expansion of water when heated (typically PRV will weep when this occurs)."


That and 30 yrs. of operating boilers.......all kinds/types/sizes
Simple 'Thermal Dynamics'

Old-Biscuit wrote:
Over time the air pocket can be absorbed into water........then you will need to re-establish the air pocket

How would you know that?

Old-Biscuit;
Good explanation!

2oldman wrote:

enblethen wrote:
The water heater needs an air space near the top. Water should not be over the pressure relief valve port.

How do you control that?

Normal filling of water heater will establish the air pocket by design of tank and position of dip tubes.
See previous picture.......

Over time the air pocket can be absorbed into water........then you will need to re-establish the air pocket or pressure will increase due to expansion of water when heated (typically PRV will weep when this occurs).

To re-establish air pocket
Turn off water supply
Open hot side of faucet to relieve line pressure
Hold open PRV via lever until water stops running out
Let PRV snap close
Turn on water supply
Close faucet

enblethen wrote:
The water heater needs an air space near the top. Water should not be over the pressure relief valve port.

How do you control that?

The water heater needs an air space near the top. Water should not be over the pressure relief valve port.

2oldman wrote:

enblethen wrote:
You do not want the water heater tank "full".

I don't know what that means.

Air Pocket

enblethen wrote:
You do not want the water heater tank "full".

I don't know what that means.

Basic RV water system

Thanks guys!