Bypass valve on water system

[Sloride]

2013 Tuscany 36.. Went throught PDI with dealer. Have CRS disease, so...
Before calling service department at dealership can someone give me some insight why one would open the bypass valve on the water side system. no help in the manual.I know the other 2 valves have to be open for normal use and to power fill the fresh water tank. Thanks

[nightriderrv]

To winterize it just a thought

[Tony Lee]

To winterise, you want to isolate the HW tank so you don't have to fill it up with antifreeze, but you still need the antifreeze to get past the HW tank to fill all the hot water lines.
So you close the inlet and outlet valves and open the bypass valve.

For normal operation you reverse all three valves

[H. Miller]

Have also read that some folks will open the water heater bypass valve to varying degrees so that bypass water and scalding water heater water will mix in the hot water lines... Never tried this but it makes sense.

[chboone]

Don't forget to drain the water heater when you bypass it to winterize the coach.