Originally Posted by groswald
Makes perfect sense. I can now die happy having seen that mystery solved.
Both Atwood and Suburban (tanked) water heaters come pre-set to 140 degrees. It's done so you can get a complete shower with just 6 gallons of hot water (to mix with cold to get a useable temp). It's too hot to be safe, but it's been that way for a very long time. It's the main reason I prefer knobs to levers on the shower valves - less likely to knock one with an elbow and shut off the cold water.
The standard thermostats are fixed and can't be adjusted. You can buy a replacement 120 degree unit from Atwood. Not sure about Suburban.
I don't know of many RVs that have mixing valves, just separate knobs for hot and cold. Some of the high end DPs and customs may have 'em. Not sure about my Tiffin, but I think I'll find out.
Atwood T-stat is 140*F & ECO is 180*F
*T-stat Closes for reheat cycle at 110*F
**ECO will reclose at 150*F...but Fault Light/Lockout has to be reset by turning switch OFF/back ON
Optional T-stats are 130*F
...but many websites list them as 120*F (Atwood does have a 120*F optional t-stat anymore....haven't for many years
Atwood does have an Optional an 'Adjustable' T-stat... 110*F - 150*F (replaces OEM T-stat---same position with a bracket
****I'm not fond of them...bracket is flimsy, hard to reinsulate and rheostat contacts corrode due to exposure to elements
Note since 2004 only One Set of T-stat/ECO needed for electric & propane operation----DC Controls for both functions
Atwood has an XT Model that uses a 'Mixing Valve"
T-stat is set for 160*F (ECO still at 180*F)
Mixing Valve Output is set for 130*F (Factory Sealed ---Fixed temp BUT one can remove seal and adjust output temps. Biggest issue is Hot to inlet of Mixing Valve gets clogged/scale-calcium and no more hot just like warm of COLD ----PITA
This Years Model......New Atwood 6 gal and the '9 gal XT version' have been revised to incorporate the Electric Element into the Front of WH Tank vs Backside of the previous versions
Combustion/Exhaust Chamber has be 'stacked' in the middle section of tank so element could be installed on right lower section (Outside compartment)
Previous versions used a Diagonal Combustion/Exhaust 'U' Tube that afforded greater surface area for heat transfer
Not sure how the 'Stack' Tube compares with the Diagonal for heat transfer (Atwood was a bit better vs Suburban cause Suburban uses a 'stacked' Tube on far right side. They compensated by using a 12,000btu burner assembly vs Atwoods 10,000btu one
Suburban T-stat is 130*F & High Temp T-stat is 170*F
*T-stat closes for reheat at 100*F
**High Temp has to be 'Manually' Reset via Push Button when temps have dropped below 140*F
Suburban has an Option set 140*F/180*F
Suburban uses two separate sets
120VAC Set for Electric element
12VDC set for Propane
**So when replacing make sure you get the correct voltage set
^^^^^^probably more info about RV Tank Water Heaters then you wanted/needed to know