Hi guys, in my house, I've got a loooong delay in getting hot water. No surprise, I've got 3/4" supply lines & long pipe runs. Anyway, my 2nd floor bath is nearing 40 years old & now I'm taking it down to studs for a redo - if I'm going to do something about the delay, now's the time. House has a tankless heater, so once the cold has moved through, there's "endless" hot water (love that thing!). i.e. I'm just trying to see if I can do anything about the delay.

So... I've been told a small point of service heater will work (not a second tankless, yikes too expensive. A regular unit keeping a few gallons hot). I'm told it will be great, a seamless transition. But... I dunno. Sure, fast hot water, but I would have thought then I'd get a long run of all the cold water that was standing in the pipes, then hot again. Does it really work like my guy says?

If so, the next question is, how do I size it? I was considering opening a tap into a bucket & measuring the volume until hot water arrived. Would that be about right?

So what do you think - are the little POS heaters good for this? Any other ideas? Should I just leave it alone? I'll be saving water anyway just using modern fixtures. But it really is a long wait, so- Thanks all for your advice

the time to have thought about long wait time was before installing a tankless heater. some brands are set up so you can run a recirculating loop off of them and some are not.
there are some diagrams here. see if any will help you.

[www.google.com]



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A 10 gallon POU water heater will work fine. You won't feel the slug of cool water between the tankless and the POU because it gets tempered by the hot POU water and long before you've used the 10 gallons up, the tankless hot arrives to save the day.