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Is there a device that will run cold water out of pipes?

Rather than have my dishwasher fill with cold water and then heat it up by the coil, I want to run hot water into the dishwasher, but the problem is that a significant amount of cold water will be in the pipes, so I need to drain that cold water out of the pipes leading to the dishwasher before letting it start to fill. Is there any device that does this? Kind of a valve that only opens when water is at a particular temperature?

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    There are recirculating pumps that recirculate hot water from the tank to close by the fitting, need a pump and extra piping. There are tankless water heaters. Think the cheapest would be to add a tee and a drain valve, manual work, but a few bucks and a couple of minutes will give you hot water to dishwasher at the beginning.
    – crip659
    Commented Apr 23, 2022 at 12:31
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    No, the cheapest is to run the hot water on the kitchen sink until hot water comes out….
    – RibaldEddie
    Commented Apr 23, 2022 at 12:35
  • You don't want a valve that opens at a particular temperature because without the water running, it will not heat up.
    – Criticizing Israel not allowed
    Commented Apr 23, 2022 at 14:23
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    It's cheaper [& 'greener'] to let the dishwasher heat it than waste the hot water left in the pipe. That's why all modern devices in EU have only a cold feed, no hot at all.
    – Tetsujin
    Commented Apr 23, 2022 at 15:56

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You’re overthinking it. All the dishwashers that I know of are beside the kitchen sink. The dishwasher either gets it’s hot water supply from directly under the sink and shares the stop valve with the hot side of the sink, OR the dishwasher is tee’d off the same line as the kitchen sink on the other side of the wall or floor.

So just open the kitchen faucet on the hot water side until steaming water comes out of the kitchen sink. That way, the hot is in the pipe.

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    I would like to avoid that manual step.
    – Tyler Durden
    Commented Apr 23, 2022 at 13:00
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    Manual is free. Automatic costs. Exercise is good for you.
    – crip659
    Commented Apr 23, 2022 at 13:17
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    Hit the "Rinse & Hold" cycle, when it's done insert detergent and hit the real cycle. Gets some of the crud off & gets the hot to the machine.
    – Ecnerwal
    Commented Apr 24, 2022 at 15:27
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I solved that problem with all the hot water taps in my home. I added a circulation pump and additional piping from the three far runs back pump. Each of those runs has a check so water can flow from the ends to the pump. As I remodeled I moved the circulation pipes as high as i could get them, the shower is about 6" below the valve. The output of the pump goes into the bottom (clean out) of the hot water. The pump cycles with a thermostat. We now get hot water in a few seconds instead of waiting for a long time for it to warm up. The pump does not run that much and draws less than 100 watts. I installed this with a Tyco cartridge pump about 20 years ago.

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  • Pump costs 100watts when running (not much) heat lost in the pipes costs considerably more, re-heating that water. If the cost of water is high relative to the cost of energy, it's a win. If not, it is a convenience with a considerable cost.
    – Ecnerwal
    Commented Apr 24, 2022 at 15:30
  • I heart the area 9 months of the year anyway so no big loss. Currently natural gas is inexpensive.
    – Gil
    Commented Apr 24, 2022 at 19:48

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