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Mothership66 · 06-01-2016, 01:57 PM

Hi, this is the first time I've played around with these valves. Problem is I'm not sure how to set them for normal water heater use. Was able to open the bottom one and fill the water heater up. Turned on heater(using electric now instead of LP) and I can hear water heater as it operates. But I only get a few seconds of not so hot water at first, then it goes cold. Been heating for at least 3 hours now. Does it need longer? Manual calls for one of these to be closed for normal operation, but which one? Very vague diagram in the manual. It's a Atwood GE16EXT and I have a 2008 DAMON Tuscany 4072. Thanks for any help!

Mothership66 · 06-01-2016, 02:01 PM

Sorry, there was supposed to be a picture of the valves...

Mothership66 · 06-01-2016, 02:04 PM

Here is a closer view...

Waiter21 · 06-01-2016, 02:07 PM

If the valves are similar to mine,

To bypass the water heater:

Close (shut off) the "COLD IN" and the "HOT OUT", Then open the "BYPASS"

To use the water heater:

Open the "COLD IN" and the "HOT OUT", Then close (shut off) the "BYPASS"

The photo shows the vales in the use water heater mode.

Water heater bypass valves | 2001 Coachmen Mirada 300QB

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Waiter21 · 06-01-2016, 02:16 PM

Looks like you posted photos of your valves the same time I posted...

i can't make out the valves in your photos to see what they are connected to.

Mothership66 · 06-01-2016, 02:41 PM

Thanks for the reply! Here's some closer shots. Hope you can see what's what in there. This is the upper valve.

Mothership66 · 06-01-2016, 02:43 PM

The upper and middle valve

Mothership66 · 06-01-2016, 02:46 PM

And the lower and middle valves. The pics posted rotated 90 degrees to the left. So rotate to the right to get the actual orientation.

Old-Biscuit · 06-01-2016, 03:43 PM

For NORMAL Operation:
Top valve is HOT outlet *OPEN (red PEX line)
Middle valve is BYPASS *CLOSED (white to red pex)
Bottom valve is COLD inlet *OPEN (white PEX line)

Your issue sounds like the 'Mixing Valve' is clogged.

VERY Hot water (160*F) comes out of WH tank directly into mixing valve. (Mixing valve screws directly into WH Tank)
Cold water from inlet supply line connects to bottom of mixing valve to regulate the very hot to a set temp of 130*F which is what should come out the side of mixing valve feeding the hot water plumbing system.

Mixing valves have this common issue of getting clogged from WH tank debris/scale/calcium.
When the HOT from tank to mixing valve clogs the cold water flows thru mixing valve into hot water system

Sometimes you can remove mixing valve and soak in CLR and clean them out.
Most times they end up being replaced

Idea is good.....design is flawed because it relies in owners to keep WH tank flushed/rinsed/clean of debris/scale/calcium

Less expensive mixing valves are available at Lowes/Home Depot etc.
1/2" thermostatic valve

Mothership66 · 06-01-2016, 05:53 PM

Thanks for the help! I understand it so much more. Also, I tapped lightly on the mixing valve with a hammer. Noticed a different noise and heard a little more water flowing through it afterwards. And now there is very hot water flowing throughout the motor home. I will clean or replace it soon, but for now, this will get me by. Thanks again guys!