Originally Posted by Hibby
AW Warn, those are both great thoughts, and I will try them tomorrow night. The trailer is relatively new, and I have no problem with cold water pressure, so I don't think it's scale, but I'll check to be sure. I will definitely try the water bypass valve in different positions.
Bigventure & Lewster, Here's a picture of my valve setup:
The yellow valve is the bypass, and I believe the larger metal cylinder at the top of the water heater is a mixer valve....
If you look at your water heater, you will see that it is an Atwood XT model. These units purposely over heat the water in the tank to about 160ºF and then mix or 'temper' it down by adding cold water to the extra hot water exiting the tank by the silver valve assembly that you have in your photo. You can see the cold water line entering the valve from the bottom. The now tempered hot water exits out the side.
I have seen many of these units with the same problem that you have. If you read your owner manual, you will see some fine print that details how you should flush that valve with vinegar on a regular basis to avoid calcification within the thermostat control section of the tempering valve. Problem is....I HAVE NEVER MET AN RV OWNER WHO DOES THIS.
The result is....you have to change the valve in order to get hot water again. You SHOULD NOT by-pass this valve by removing it, as 160ºF water WILL BURN YOU.
PM me if you need any other detailed information.
PS: With all due respect Bigventure, If you are not familiar with the operation and components of an Atwood XT model water heater, please do NOT provide misinformation that is based either on a guess or your experience with a standard water heater. His bypass is probably in the operational position and NOT backwards. The yellow valve at the bottom of the photo is a shut-off valve for the cold water supply to the water heater, NOT A BYPASS.