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thinksnowwhat
On Demand Water Heater

I recently installed a Reni on demand water heater...It takes an extremely long time to get hot water to my faucets, even the ones closest to the heater..I have upgraded 70% of the piping to 3/4 inch. And have upgrade the propane line and tank to handle the new volume. Any helpful hints on how to get hot water to our faucets quicker so we do not have to waste so much water?

Sten
Re: On Demand Water Heater

On Demand water heaters are known to be slow at providing hot water, here's something I got from the Net.

A gallon of water will fill 63 feet of ½ inch galvanized iron pipe, 36 feet of ¾ inch galvanized pipe, or 20 feet of 1 inch galvanized pipe. In the case of type K copper pipe, a gallon of water will fill 88 feet of ½ inch pipe, and 44 feet of ¾ inch pipe.

This means that if you run your faucet at 2 gallons per minute, and you have 1 inch galvanized pipe, the water will travel 41 feet per minute. However, if you have ½ inch type K copper pipe, the water will travel 176 feet per minute, quite a difference. So the smaller the diameter of the pipe, the faster the hot water will reach the fixture, given the same flow rate.

Also I don't know what you did as far as upgrading your Propane Line but there are things that should be considered, BTU's, Length, pipe size. All this is measured in water column or the amount of pressure it takes to move a certain amount of water an amount of inches. With Natural Gas you should have 7 inches of water column on the incoming side and 3 1/2 on the manifold side, this is adjustable at the gas valve, (NOT TO BE ADJUSTED BY ANYONE THAT HAS NOT BEEN PROPERLY TRAINED TO DO THIS).
I believe the water column for Propane is 11 inches which could change if the pipe dia. has been altered but the sizing is done the same as NG but the nos. will differ. Any alterations that are done on NG or Propane should be done by a properly trained Tech

Just my two cents, I hope if someone has more info they will add to the post

alardcaretaker
Re: On Demand Water Heater

I got an on demand water heater and I love it - my water travels fairly quickly. I did redo all the plumbing in the house and have copper pipes for the hot water.

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