Roto-Swirl dip tube problems?

[Richard Moore]

Today, I had a 2005 Kenmore 40-gallon gas Power Miser 12 (12 year warranty) with "Roto-Swirl technology". It was exhibiting all the signs of a failed dip tube. Vacant home but thermostat was cranked up to max and I expected to be seeing some very hot water. I turned the thermostat down to the normal mark and soon after started filling the jetted tub to get rid of the excess heat. But I never registered anything over 120 and with only about 4" of water in the tub the temp had already fallen to 95. Back to the heater to re-check hot-cold connections (OK). Heater is not firing despite the low temps at the faucet. This cycle, initial hot quickly fading to tepid, repeated elsewhere.

I will leave it to the plumber to diagnose/repair, but I was wondering if this is a known problem with these "self cleaning" heaters of this vintage? I can't find anything definitive online, but it could be under other brand names(?). Oh yeah, also had 95psi water pressure. Could that damage the swirly thingamajig dip-tube?

[Tom Raymond]

If the stat was pegged and the temp was only 120, and it fails to fire when the temp drops, why are you looking at the dip tube?

Sounds like a bad gas valve to me.

[Scottpat]

2005 was after the bad dip tube rash that we had , I think.... I always found bits of white plastic or even gel like stuff in the faucet aerator screens. If I suspected a bad dip tube I always took a couple off to see if I could see plastic in them. Not foolproof but it did help to ID a problem..

[Richard Moore]

If the stat was pegged and the temp was only 120, and it fails to fire when the temp drops, why are you looking at the dip tube?

Sounds like a bad gas valve to me.

I did have the dishwasher going so there may have been hotter water initially. And note that I turned the thermostat down to the "normal" mark. The repeating cycle of rapid drop in water temp suggests to me that cold water is entering at the top, mixing near the hot water outlet, and not near the bottom where it would trigger the thermostat. When I was getting 95? water at the tub I could get the heater to fire, but only by cranking it way up. A bad gas valve, alone, just wouldn't explain the results I was getting.

Something odd is going on. I came, I reported, I'm done. I did suggest in the report that it might be a dip tube issue, but I ultimately left it to the plumber to evaluate and repair. Just curious if there was a known recurrence of the old dip tube problems with these rotoswirl types.

[Richard Moore]

2005 was after the bad dip tube rash that we had , I think....

Yeah, long after. I thought it might be related to the "self cleaning" action of these units. I could have sworn I read something, somewhere dissing these. Maybe not. I suspect if it is the tube in this case, that it has fallen off somehow rather than crumbled like those older ones.

Sadly, as is often the case, I'll probably never find out. I'm not about to contact the seller, whose house I just trashed inspected, to ask how they fixed it.