Question: I have read in a maintenance manual that the ideal temperature for incoming water to a dishwasher is 150F.

In my house, the hot water heater is currently set to 135F and it cools on traveling around the house, so the typical faucet temperature is around 120F.

I have considered up the temperature of the water heater to 150F, but in that case it is recommended to have a thermostatic valve reduce the temperature to 120F, which would be no better than what is happening now as far as the dishwasher is concerned.

I could boost the water heater temperature to 155F which would result in 150F water reaching the dishwasher, however, then all the faucets would also have 150F hot water, which is pretty hot.

The only way I see around this is to create a special hot water line that goes to the dishwasher and clothes washer that comes directly from the water heater and put the water heater at 155F, then put a valve on the water supplies to all the rest of the house. Is this is the "proper" solution, or is there another way to get the right temperature to the appliances?

Answer: 
### You don't. Let the dishwasher do it for you.

> 
> I have read in a maintenance manual that the ideal temperature for incoming water to a dishwasher is 150F.
> 
> 
> 

Was it a maintenance manual for *your actual dishwasher*? If not, I would ignore random advice (no better than advice from some stranger on the internet...).

**Most dishwashers now automatically heat water as needed to the necessary temperature for optimum performance.** This avoids exactly the problem you mentioned - water hot enough to clean effectively and to sanitize dishes is also hot enough to quickly burn people. Some dishwashers (I think typically European models) are even designed to run with cold water - heating water from *cold* to *very hot* as needed, not just *hot* to *very hot*. That being said, I would recommend connecting your dishwasher to the hot water line rather than the cold water line, unless your manufacturer specifically recommends otherwise, because:

* Electric heat is generally more expensive than natural gas or other forms of heating. If your main water heater is electric then any heating by the dishwasher will cost the same as your main water heater, and if your main water heater is something else then any heating by the dishwasher will cost more. I can't see any normal scenario where using your dishwasher to heat from *cold* to *hot* will actually save any money.
* If your dishwasher runs some cycles without heating the water to *very hot* (e.g., perhaps a regular rinse cycle as opposed the main wash cycle or a final sanitary rinse cycle) then using hot water instead of cold water will be much more effective.
If your dishwasher is already connected to the hot water line you can get a few degrees hotter water by insulating the water line. The greater the distance from the water heater, the greater impact this will have.