Dishwasher suddenly not working due to lack of hot water from tankless

[Saraholland22]

Dishwasher worked fine until about a month ago. Repairman said the machine works fine including thermostat and heating element. He said the water getting to machine isn’t hot enough. This is, again, a new problem. There is a designated valve to the dishwasher rather than shared with hot water to faucet. I have switched valves to see if there was any change with no luck. The dishes are dirty and wet at end of cycle. Water to the faucet takes about 40 seconds to heat up, which has always been the case. What is a possible reason this change has occurred recently. Would having hard water have anything to do with it?

 

[Terry]

What model dishwasher do you have?

Normally under the kitchen sink, the shutoff for the dishwasher is on the same line as for the kitchen faucet. Sometimes I would run the hot to the kitchen faucet before turning the dishwasher on. Most dishwashers will clean even if the water is cold though. It makes me wonder if it's something else going on.
The dishwasher I have now, a Bosch, will preheat the water, so no need to run the kitchen sink now.
Some dishwashers have a Sanitize option that has it's own water heater and heat dry function. Were any settings changed?

 

[Sponsor]

 

[Jadnashua]

Mine, like Terry's, has a preheat setting if the incoming water isn't hot enough. In reality, dishes tend to get cleaner, easier, if the water is hotter than the 120F that's more normal in a home. Depending on the detergent you use, some won't even dissolve well if the water isn't hot enough.

It's not all that hard for the switch (mine has a switch for this) to be accidentally flipped off.

 

[Jeff H Young]

My kitchen takes forever for hot water 2 story house w/h in garage the hot goes to a manifold in attic then back down underground and to my island dishwasher works perfect? I don't know how it works but you could steam the Titanic with it. buy a new dishwasher that's how my wife fixes those things buys a new one before I get my tools out

 

[WorthFlorida]

Dishwasher worked fine until about a month ago......... The dishes are dirty and wet at end of cycle. Water to the faucet takes about 40 seconds to heat up, which has always been the case. What is a possible reason this change has occurred recently. Would having hard water have anything to do with it?

The number one over looked item is the spray nozzles. Check that they are not clogged up with food particles and paper such as price stickers. My daughter in law was ready to buy a new dishwasher because nothing was getting clean. I removed the spray arms and cleaned the clogged nozzles. It can be a hassle to clean out the debris.

With hard water you would have always have had the problem. Hard water will leave spots everywhere and make it very difficult to dissolve the detergent and may reduce the cleaning of hard dry food items such as eggs. With a water softener you only need 1/2 the amount of detergent. If you have a water softener and it is not working, you would notice it.

Since the tech stated that the heater is working, we do not know what type of heating this machine has. During the wash cycle the water should be very hot, steamy if you open the door during the wash cycle. As others have stated, even warm water a dishwasher can clean pretty good. Depending on your model, some have a water heater under the machine for the wash water with no heating elements inside the dishwasher. The other type is the bottom inside heating element is turned on to heat the water or only during the drying cycle. Bosch brand dishwashers use an internal water heater and the drying (they call it condensating) is accomplished by the hot water temperature absorbed by the dishes and glass.

 

[John Gayewski]

Can you run the dishwasher and feel the water line? You need to make sure your tankless heater is getting enough flow to heat the water. If your line isn't getting hot check the hose to the appliance. Hard water will restrict a flex hose very easily.

 

[Reach4]

delete.