Fresh Water Pressure

[Miket99]

I can't get my head around my fresh water system/plumbing. I have two fresh water tanks and two Whale 6 gal water heaters. I can select the flow from either (or both) water tank(s)as well as each hot water tank. The system has a 3 GPM water pressure pump and an an accumulator.

All appear to be working correctly except I am not getting equal hot water pressure to the shower (but do get cold water pressure) The shower gets too hot and turning the hot side of the shower mixer doesn't cool water down once it is hot. I thought the shower mixing valve inside the shower was bad but when I got it off and turned on the water I get this (see image below)


I have owned this boat for four years and the shower has always been a bit unpredictable. It's a 2002 built boat and I do not think it has a hot/cold mixer built into the plumbing system before the shower mixer.
Why is the hot flow so much less than the cold?

[Lepke]

Water heaters need a check valve to prevent the water, as it heats and expands, from going into the cold water line. If it expands into the cold line, when you first turn on the shower and cold doesn't seem to cool the temp. The pressure/flow difference could be some partial blockage, collapsed hose, or a convoluted plumbing route.


We don't know your plumbing system.