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Old 03-24-2010, 11:18 AM   #1
water flows downhill
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Extra hot water tank to boost tankless?

The new 180000 Btu Rheem tankless is too far from the kitchen, so there is long wait for hot water to reach there.
Would a 4 Gal. electric tank big enough to supply a dishwasher and a kitchen sink?
Is it a good idea to use one way valve (s) to isolate the water loop for the sink and dishwasher when the added tank is installed?
I thought that way the tankless would not sense the water flow and turn on when the kitchen sink or dishwasher is used.
Thanks in advace for any advice.


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Old 03-25-2010, 10:31 AM   #2
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I think 4 gallons for a dishwasher is not enough. I think you need at least 15 gallons.

The 4 gallon tank will not heat up again electrically fast enough for the next stage of the dishwasher cycle to draw from. (It might for a gas heater).

There is no easy way to put in an automatic sensor or check valve that keeps the tankless off when you draw a small amount of water but turns the tankless on when you draw water over a longer time period. And when the tankless finally goes on (probably using a manual remote control) the cold water that entered the auxiliary heater tank after the first small usage as well as the cold water in the pipe going back to the tankless has to be run out (consuming time) before hot water from the tankless arrives.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 03-25-2010 at 10:36 AM.
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