Tankless hot water heater wastes so much water.

Asked by Rich
Greer, SC

We have a ranch home - 30+years - installed a tankless water heater and have never ever been happy with it. Gallons of water are being wasted while we wait for warm - not even HOT water - to be present. Is there anything we can do to correct this? Then, you can use it for a short time - then all of a sudden it turns cold again! Any advice would be appreciated.


Sean Lintow Sr

Answered by Sean Lintow Sr

Naperville, IL

SLS Construction & Building Solutions

February 6, 2014

The first big issue I sense is where in relation to each other are the hot water taps & the water heater? The further the distance... the more water you waste waiting for hot water to arrive. The second issue involves the type / size of the system. This becomes a big factor as more BTU's are required to heat certain amounts of water - so at 1.5 GPM in a shower where the incoming water is at 70 degrees, requires a lot less energy as compared to 1.5 or even 3 GPM when the water is at 50. You can fix this with either a bigger unit, reducing the flow needed or doing what some do up in MN & other areas & utilizing a holding tank to raise the incoming waters temperature. The next item I see is what is referred to as a cold water slug. The main reason for this is the flow is interrupted (you turn down the faucet for a bit while shaving) which cuts the burner off. As the flow once again increases the burner kicks back on but you have a slug of cold water in the lines. You may also have an issue if the flow you are calling for drops below a certain level, for example you turn the faucet all the way up & then ease it back when water starts flowing - the only real fix for this is seeing if there is a setting on the unit to allow it to kick on at a lower flow. For more information on shortening runs & possibly seeing if a recirculating pump might work for you:

Tagged In: tankless, tankless water heater

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