My house has a solar and electric heating mechanism which provides hot water year-round.

However, when opening the hot water in the kitchen and toilet faucets, I get cold water which gradually get warmer and warmer, till they are actually hot. The process can take between 5 seconds to two minutes, depending on the house temperature. This is annoying and wastes precious water.

I once heard that there is a way to get instant hot water without a heater, by circulating water between the cold water line and the hot water line, but I could not find any details online.

Is there a way to get the hot water flowing instantly from the home faucets, without a faucet heater?

2 Answers 2


No method is "instant" but there are long-used and accepted methods of recirculating your hot water piping system back to your water-heating appliance, which keeps the line at least warm (or hot) depending on the chosen method. Another alternative is "point of use" water heaters at each user location, this is common in some european countries and is gaining traction in the U.S. as well.

You should know that these methods may not be "wasting precious water", but will use more of some other energy or resource, you don't get something for nothing.

This thermosiphon system I have in use at my home, relatively quick hot water and higher natural gas bill: enter image description here

This method is similar to piping arrangement of the thermosiphon system, but utilizing a pump. Very quick hot water, higher natural gas and electric bill: enter image description here

This system uses a proprietary crossover valve to create a recirc system, I have no experience with this and the arrangement seems dubious to me:

enter image description here

Then there are the "point of use" units. The additional cost of the units and the resources required to manufacture them would likely offset any environmental gain by not wasting water, but they get hot quick.

  • 1
    Note that the "Lobster" scheme causes the cold water feed to be hot and one has to run the cold faucet for some time before getting cold water.
    – wallyk
    Commented Dec 30, 2016 at 21:20
  • The circulation system is used by medium and larger hotels/motels.
    – wallyk
    Commented Dec 30, 2016 at 21:21
  • Recirc systems are used in many homes too. Commented Dec 30, 2016 at 21:32
  • 1
    Recirculation systems have to be very well insulated if they're not going to waste a lot of heat (which may then need to be removed).
    – Chris H
    Commented Dec 30, 2016 at 22:33

Below is a link to a system for redirecting water from the hot line back to the cold supply until it warms up. This is not instant, takes the same time as standard but keeps water in the lines. This is a lot of trouble and expense to save a little water unless you are in an area that is really short of water. The poor man's technique with a standard system is to use a bowl or a bucket to collect the initial cold water and use the water in the garden, or to flush the toilet.


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