*** Dripping relief valve ****

The expansion tank is a good idea. City codes are starting to require them on home water heaters. I used to crack open a hot water faucet when first starting up the water heater to take care of the initial expansion from a cold start.

dutchev wrote:
We have a suburban water heater. Had our relief valve replaced but it still seems to drip off and on. Both on gas and electric. Although more on gas. One rv tech says to check the temp of water on gas then elecrtic. I did and they are just a few degrees different. The rv guy told me that he has had some situations when it just will drip no matter how many Valves you replace. His suggestion was to hook up a little tube so that the dripping water stays outside of the coach. Any ideas?

At the expense of a small amount of hot water capacity, on a Suburban there are plastic dip tubes in the inlet and outlet. The top one points up, bottom one down. If you pull the top dip tube out, you can either just leave it out or cut it off a bit to make the air pocket larger.
This doesn't work with Atwood- they use welded in dip tubes.

Or get a small surflow expansion tank. IMO should be standard on all RVs.

Water system in an rv is a 'closed system'.
When water is heated it will expand.
An air pocket at top of water heater tank allows for this expansion (air can be compressed...water won't)

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


Just curious....what was the temperature of the water when heated with gas..with electric.
Normal t-stats are preset to open when water temp reaches approximately 130*F