Why did you install that particular valve? Remove it and install this please.

@Joseph Corlett, LLC it was recommended by a worker from Home Depot after I described to him that I would like the ability to shut off the water. is the valve the culprit? why is that? I figured if the hose melted previously without the valve added, the valve shouldn’t be the problem.

Hi @kaseki, thanks for the explanation. It is a hot water line feed to the dishwasher. Only the valve end of the hose was hot, not the rest of the hose. Shouldnt the rest of the hose be just as hot? The hot water tank was newly installed a year ago so it should meet modern regulations.

The rest of it is insulated. Did you actually measure that 210°? Is hot water from your sink scalding hot or just hot?

@foodonastump the water from the sink is hot but not scalding hot. I measured it. So strange...

The highest temperature from the sink faucet is 120F.

Does your dishwasher have a water heating function?

if yes, perhaps a check valve is not working.

Only if hot water is flowing in both lines will both lines be hot away from the junction point.

Still to be understood is the "smoke" observation. @User's observation seems on the right track but perhaps the dishwasher is actually boiling the water it has to work with. Superheated steam would very likely cause failure of this type of flex hose; they don't build them with Teflon liners like high performance brake lines. So perhaps whatever thermostat is supposed to regulate the dishwasher's water temperature has failed and allowed uncontrolled water heating. Steam pressure could also overwhelm whatever check valve might be in use.

Almost has to be. Can’t imagine the water heater overheating that much without multiple problems all over the house. When running hot water in the sink, is the connection at the faucet end of the supply unusually hot? If not, then the DW is all that’s left.

Looking at HD’s site, Brasscraft braided line is rated for 140°, 180° intermittently. If 210° is accurate, this supply is being subjected to far higher.

Just want to say thanks to the OP. My water’s been far too hot but I’ve never bothered to do anything about it. Just checked and I’ve got 146° at the kitchen sink, even though the water heater is set for 130°. I’ve knocked it down 10° and will monitor. Might have saved me some problems and some oil.

I think you are all on the wrong path here:

I think this is an electrical problem - and it's grounding through the water supply line. I think that's what is causing it to heat up.

Make sure the dishwasher is properly grounded. Put a multimeter between the metal chassis of the dishwasher and a known good ground. If there's voltage, you have your problem.

I was wondering about electrical but would be be so localized?

Some clues:

"The end where it feeds into the dishwasher is not hot" : This isn't backflow.

"I smelled something similar to smoke / fire": This isn't hot water

"The temp was 210": I don't know how that was measured, but no water heater would output that temp without multiple safety devices kicking in (over-temp, and T&P valve). An electric heater can bypass the over-temp safety in certain situations, but not the T&P unless it's been capped. If that was the case, there would be steam blowing out of every hot water faucet, not just the dishwasher. There is no situation where water is heated to 210 in residential plumbing in a working situation. Period. The dishwasher isn't designed to heat water that hot - it would melt plasticware and would be a pressure cooker, not a dishwasher.

"Last two lines melted":

This is heating up because of a large electrical current being passed through this fitting - I will bet anything. The plumbing connections are high resistance, and they are heating up.

"The end where it feeds into the dishwasher is not hot" : This isn't backflow.

I completely missed that in my initial reading. My money’s on you.

This will probably sound ignorant - what are examples of known good grounds?

The ground terminal of an outlet would be a good choice. You can prove it's good by measuring the hot of the outlet to the ground. If you have 110-130 volts, it's a good ground.

Then measure from the metal body of the dishwasher to that known good ground as it's running through a complete cycle. If you see the meter jump up at all, you have an electrical problem.

Yup, the meter jumped. Thank you and everyone so much! Now got to figure out if I can fix it or it’s a job for an electrician.

I’m thinking appliance repair. Good luck. How old is it? Black Friday/Cyber Monday sales are still going on, though some inventory is low.

"Now got to figure out if I can fix it or it’s a job for an electrician."

From your questions and statements above, you should get a repair person -

There are two issues: one issue is a house wiring issue which is why isn't this dishwasher properly grounded? The other issue is why is there a ground fault. I suspect if it was properly grounded it would flip a breaker. You have to resolve both issues.

Good thinking Jake!

I bought the house a few years ago and it came with house so Im not sure how old. but probably pretty old because the fridge from the same set died a year ago.

If there is enough electric current flowing to heat up the valve, I'd expect breakers to trip. If that doesn't happen, you have bigger problems that really need to be addressed.

@Mei

If it's an older unit, it's probably a better idea to replace it. New dishwashers aren't that expensive - vs the cost of an appliance repair person making a couple of trips (diagnose, then come back to install the part).

Then all you have to do is make sure the new one is properly grounded. If you install the new one, make sure the ground wire is good (use your meter from hot to ground). Then make sure it's connected to the grounding wire/terminal on the new dishwasher.

Is it plugged into that receptacle or hard-wired? That receptacle is not a GFCI. Is it split between the DW and the disposal? Do you have GFCI breakers in the panel for these circuits?

A 200* WH with a bad pressure relief valve will soon blast it's way out of the basement through the floors and the roof, and end up on the front lawn.