Water heater wiring

[yowmemperor]

I'll admit I only did one search before posting, but I'm tired and leave tomorrow lol.

I replacing an old domestic wh with a new suburban. Old was propane, new is Propane or electric. Looking at the wiring, the wires to the old wh are green, blue, and brown. The new one is green, blue, and red... do I just wire the red and brown together?

Also, if it's plugged in and hooked to Propane, which takes priority?

Thanks in advance, it is appreciated!

[Old-Biscuit]

Electric and Propane are separate
Can use just propane
Can use just electric
Can use BOTH at same time

Each has it's own set of t-stats:
Left set...120VAC (electric)
Right Set...12VDC (propane)
*Electric and Propane T-stat opens at 130*F/Close at 100*F for reheat
High Temp T-stat trips at 170*F...Manual Reset

Electric is direct...120VAC from 15A Circuit Breaker to AC Junction Box on right side of tank (looking from the rear)
*From Junction box OEM wiring goes to On.Off switch in outside compartment then to/thru set of t-stats then to element when heating called for

Propane uses 12VDC from a fused source to On/off switch with Fault Light. From switch to DC Junction box on left side of tank (looking from rear)
*From Junction bx OEM wiring goes to/thru set of t-stats then to circuit board on backside of tank. DC then goes to gas valve/spark electrode when heating called for

DC wiring is:
Red ---12VDC POS
Green ---12VDC NEG/Ground
Blue ---12VDC POS from circuit board to Fault Light on switch

Old Atwood
Brown ---12VDC POS
Green ---12VDC Neg/Ground
Blue ---12VDC POS from circuit board to Fault Light on switch

[yowmemperor]

Thanks OB! So with 120 it still uses the same water heater switch? Or it just starts heating when plugged in?

[Old-Biscuit]

Originally Posted by yowmemperor

Thanks OB! So with 120 it still uses the same water heater switch? Or it just starts heating when plugged in?

When wired up....
15A CB in your Main Power PANEL with Romex run to the AC Junction Box
OEM wiring from box to the On/Off Switch In the Outside Compartment .... lower left/below-beneath the gas valve

want to use the Electric ...then YOU turn on the OEM switch
*you can also run the romex wiring from the 15A CB to an Inside Switch then from switch to AC Junction Box
***Many times a Standard household Light switch/electric box used

Inside switch and OEM outside switch wired in series...both have to be on for electric to work but can leave outside on and just use inside switch