Experience with tankless water heaters

[Wayne Whitney]

Hello,

I'm contemplating putting in a tankless water heater and have read the many discussions in this group closely. There is one issue that I haven't seen discussed, though.

As I understand it, a tankless unit needs to sense a minimum flow for a second or two before turning on/heating up. So if you are standing at the kitchen sink washing pots and run the water repeatedly for 5 seconds at time, do you end up getting an alternating flow of hot and lukewarm water?

If this is a real problem, would using a very small (2 gallons?) tank after the tankless unit fix this? Would it have other benefits? Would this tank need to have an electric heater on it?

Thanks, Wayne

[Goedjn]

On the propane powered one that we use for camping, what you get is a short burst of warm water that's already fed into the pipe, followed by a slug of really hot(*) water that was sitting in the heat exchanger, a short burst of cool water thats what fed through before the burner turns on, and then a continuous stream of warm water.

(*) Never hot enough to actually scald, but certainly enough to get your attention.

--goedjn

[Andy Hill]

Hmmmm. Can't say I've ever noticed this effect. I think between the facts that (1) there is a significant amount of hot water stored in the water pipes and (2) the heat exchanger in the water heater doesn't cool down instantaneously, the "lukewarm" phase isn't really noticeable. The initial delay to get the first hot water sure is noticeable, 'tho.

[scott21230]

Picky picky picky. Just run the water till it comes out hot. Water is still pretty cheap in most places.

[Goedjn]

Yeah, but I have to dig the pit it goes in after it's used.