The pre-set t-stats 'close' when temp cools and 'open' at a pre-set temp
Suburban uses a 'standard' 130*F t-stat and a 180*F ECO (high temp) t-stat
They come in a set. One set for electric & one set for gas. The electric is a 120V AC set and the gas is a 12V DC set.
When the 'normal' t-stat opens (130*F) the water temp (tank wall where t-stat is held tight against with a nut) has to cool off enough for the t-stat to close....roughly 110*F
If you have different ranges of t-stats the lower temp t-stat will do all the heating cause the higher temp t-stat will not cool off enough to close.
If the ECO t-stat opens it cuts off all power for that function (electric or gas) and has to be reset (the reset is under rubber cover which protects t-stats from exposure to elements and keeps them from cooling off from outside air vs tank wall temp)
Atwood uses a standard 140*F & 180*F t-stats.......since 2004 just one set for electric & gas so if problem with t-stat nothing works and if ECO opens you can't reset it..you have to wait until temp cools enough for it to close. They do have an adjustable t-stat to replace pre-set 140*F t-stat.
Simple designs....not 'smart' enough for selective heating
