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I'm trying to prevent a repair issue. Later I'll buy a highly energy efficient dishwasher. Now I'm purchasing a tankless water heater to replace the tank that just sprung an irreparable leak. I've read reports that some tankless water heaters do not heat the water going to certain dishwashers. This reportedly occurs when the flow rate required by the water-efficient dishwasher as it is asking the tankless heater for hot water is lower than the flow rate that activates the tankless water heater.

So, I must purchase a tankless water heater with a low enough flow rate activation to turn on and heat water when the highly energy efficient dishwasher asks for pre-heated water. I'm assuming energy efficient also means these machines will have the lowest hot water flow rates. But I can't locate minimum hot water flow rates on the web, in product literature, etc. I could divide the gallons used/cycle by the time of the cycle but if the spray does not last as long as the cycle, or the cycle re-cycles water, this calculation will be wrong.

Does any one know the lowest hot water flow rate in gallons/min (or other measures and I'll convert it) demanded by any of the following very efficient dishwashers or similarly efficient dishwashers (I'm not looking for numbers for all of them, just one or two should give me a good ballpark figure)???

Bosch with an Energy Factor of 1.19... SHE68E05UC, SHE68E15UC, SHV68E13UC, SHX68E05UC, and SHX68E15UC.

Bosch with an Energy Factor of 1.14... SHE98M05UC, SHV98M03UC, SHX98M0#UC, and SHX98M05UC.

Gaggenau with an Energy Factor of 1.19... [FONT=&quot]DF260760 or the DF261760[/FONT].

Thank you very much!

Gordon

I have a similar issue with my gas fired tankless water heater NR98 (N-0751M)Series Residential Tankless Water Heater (NORITZ brand). My dishwasher is a brand new, but a bottom of the shelf model Frigidaire. I'm told that because the dishwasher must take time to heat incoming water to 140 degrees (and because the tankless water heater is not kicking on during washing cycles), that the dishwasher is now takes 3 or 4+ hours. Most of the time I just shut it off out of frustration. I'm confused about what solution, if any, is available. Is their a dishwasher make and model that will work properly with my water heater? Is there some other fix?

I find this thread very interesting as I was having the same problem with my dishwasher and tankless hot water heater. I find it interesting that some suggest adding a small hot water to the system, but that defeats the purpose of a tankless water heater.

Here is the fix. I have a Rinnai and I timed how long it takes to get hot water to the sink and it was 45 seconds. It takes less than that to fill the dishwasher so I all ways had cold water in
the dishwasher. Worse yet that when the empty and fill for the rinse cycle occurred the water was cold again. I fixed it but it gets a little complicated to explain the fix. I am handy with designing home automation with micro computers(Arduino) so I designed a system of valves and a flow sensor that is controlled by a micro computer. When the dishwasher asks for water the computer shuts off the valve to the dishwasher and turns on a valve the cycles water to the sink drain for 50 seconds which at that time the water is hot. The computer switches back the valves so that the dishwasher fills with the hot water. When the dishwasher asks for water again for the rinse, the cycle is repeated. So now there is always hot water in the dishwasher and the dishes are clean and there is no caked on soap in the soap dish.