I hate having to wait for hot water especially because it wastes water in my ordinarily drought stricken area. This seems like a great solution. Is it? What are the pitfalls?
If it matters, my house is on a raised foundation and the plumbing is all upgraded to copper.
Here’s an excerpt from a fairly recent post of mine wherein I evangelized about the system I got about 10 years ago.
I would totally do that again if I lived in a single-family house or even a condo with long enough pipe runs. I’m not endorsing that brand and model specifically, but just that general concept of a recirc system.
The biggest concern for you is whether you can adequately insulate the hot water lines. If your lines were embedded in a slab, then insulation is out of the question and the operating cost would be noticeably high. Conversely, most of my runs were along the exposed joists in the unfinished basement. So in a semi-climate controlled area and readily accessible to slip foam sleeves over the majority of the hot water line runs. In my case the operating cost was truly negligible even if the pump was active 24/7/365.
The result is not “instant” hot water, but it’s warm in 5 seconds and hot in 10 seconds even 100 feet from the HWH. Magic I tells 'ya!
Here’s a quote of another poster in another thread with cites to potentially useful articles.
I’ll also point out that in the part of my post I did not excerpt I mention another handy hot water gizmo: truly instant near-boiling water for your kitchen sink. Super handy for cooking, making tea, etc. Not useful for washing. If that might be of interest to you, check out the rest of my earlier post.
I talked to a plumber about that for our former home. He said it wasn’t practical for a house like ours and would require a lot of rework of the existing plumbing. We had an on-demand tankless water heater installed, which, while not instantaneous, was continuous for as long as you wanted it. Plus no danger of it flooding the basement.
Thanks for the great information so far. My standard hot water heater is in a closet. I’m in Santa Barbara so no basement and the pipes are under the house and it rarely gets very cold here.
If the crawlspace is accessible then insulating much of the pipe runs should be an unpleasant but doable task.
We have this in Seattle. Built new 10 years ago. It’s great.
We have two hot water tanks (mainly as a safety issue for my youngest so the hotest water would never scald her). When our re-circ system went out about 6 months ago, I forgot how good it was to have almost instantly hot water. I mean it takes a few seconds for the hot water to come out of the tap instead of what seems like a minute or two.
Or, for a couple hundred bucks you can get a small instant heater mounted under your sink. We had one of those in our old house, and it was hot enough that you could make tea or coffee with it. Basically a mini tankless water heater.
That was what I originally wanted just for the kitchen. I am about to embark on a kitchen remodel and that was going to be part of it. The contractor suggested a recirculating pump so I’d get the benefit for the whole house. This sent me down the rabbit hole. As it happens, a friend of mine just moved to town and has been a licensed plumber for a couple of decades. He is building up his clientele and has some free time. He will give me a deal on the installation.
What under sink model would you recommend.
My parents’ house has this, and it was wonderful. But it didn’t work well with on-demand tankless heaters. They tried this and ended up with a multi-year problem of wild temperature swings and repeated replacements of the tankless heater by the contractor. In the end they had to choose between replacing the tankless heater with an old-fashioned kind, or removing most of the re-circulation system. Dad chose the latter since their bathroom is located directly over the tankless heater. They just endure the 4 minute wait for hot water at the kitchen now (other end of large house).
The brand I’ve used is:
Note it’s NOT for instant hot water to your main faucet. It’s only for near-boiling water at a lowish flow rate for a quart-ish of volume delivered by a dedicated mini-spigot. I can recommend this brand as solid and dependable. You will want a fresh electrical circuit run under the sink to power it.
I have a Quick&Hot unit in my kitchen, installed about 10 years ago. I use it for tea, and used to use it for my French Press coffee. It’s also great for a quick clean of a utensil 
I love it.
My mother had an instant hot tap in her kitchen sink for decades, in two different homes. I can’t recall either ever giving her any problems, or needing to be replaced. I think she mostly used it for tea and making instant oatmeal and similar “I want a little bit of very hot water right now” uses.
Sorry, I don’t know enough to give a reasonable answer. We had one in our first house 30 years ago and loved it, but haven’t had one since.