Suburban SW6D Help!

Are the bypass valves in correct position?

I've got a feeling the stat is bad so I ordered the optional 140 degree stat and will install it that will probably kill two birds with one stone! Thanks for the input!

Normal t-stat should OPEN ~130*F and should CLOSE ~100*F to reheat.

You can get a 140*F normal t-stat (they close ~110*F)

I'd change out t-stat, run it thru a cycle and test water temp at PRV.

Good luck!

Ok, Back home after a week of military style showers,drained hw heater and looked as best i could, I can see the cold water inlet and dip tube which appears to be fine although it looks to be natural translucent polyethylene rather than black. Tried every which way to see the hot water outlet but could not get the angle to view it and my inspection mirror was just a hair too big to fit through the opening. I did not see anything lying in the bottom of the tank. I haven't checked the temp of the water as suggested but it seemed plenty hot just wouldn't stay that way. It did seem to take a bit longer than I thought it should to kick on while the hot water is being used, I'm wondering if the thermostat could be the culprit not allowing the heater to kick on until too deep into the cycle for it to recover. (I know it won't actually recover just prolong the inevitable). If shut off is set at 130 degrees what should kick on temp be?

Same issue with another poster on a 2013 unit. That post....LINK

Sounds like Suburban has some issues with 'dip' tube falling off.

Instead of cold inlet being directed down towards bottom of tank, without the dip tube it cold water would flow in and mix with the hot water more readily

IF the cold inlet dip tube has fallen off.

But 2 Suburban water heaters both 6 gallons sizes running out of hot water after roughly 3 gallons sounds like a problem with the dip tube on cold inlet.

Drain WH and with a strong pin point flash light look inside WH tank for a piece of black tubing laying in bottom.
IF so that would be the dip tube.
Suburban will give you a new one FREE. Then the cold inlet has to be disconnected, the cold inlet nipple removed and new dip tube installed.

Course that is IF it's the dip tube.

When WH turns after a heating cycle......need to test water temp with an instant read thermometer at the Pressure Relief Valve.

CAUTION: Water will be under pressure and HOT.
It should be ~130*F that is factory pre-set on the normal t-stat)

Strange......cold water after 3 gallons

Post back what you find/learn.