If not already done, insulate your existing hot water pipes in the basement.

Least expensive add-on is to install a "gravity loop" in the basement. May or may not be do-able based upon your access.

Second would be to add a loop and a circulating pump. A small Taco will be fine. The goal of either of the insulation and either of the loops is to keep the water in the pipes hot at a location closer to the bathroom. You can still have a supply delay, but it won't be as significant.

Third option is to add a point-of-use heater in or near the bath. It can be tankless, there are electric tankless units. Or it can be a small electric tank unit.

Tankless units are very small and can pretty much fit anywhere. Just ensure your main electrical supply can handle the added amperage. Since you're just looking for a start-up point-of-use unit and not a continuous whole house unit, you're probably fine there.

Tankless units are rated at "GPM delivered vs delta T", meaning that they can raise the water temp a certain number of degrees at a certain flow rate through the heater. The more flow, the less the temp is raised.

Some don't turn on at low flow rates, for example if you leave a trickle flow of hot water on while shaving.

The advantage to you is that this will not be your primary heater. You just want this thing to kick on when hot water is first demanded in the bathroom. Once the main water heater in the basement gets hot water into your bathroom, the tankless unit (or tanked unit if you went that route) will simply act as a flow-through device and it will turn off on its own. Or if it's t-stat is set higher than the water your main tank is supplying, it'll act as a temperature booster.

Hi mongo-

Thanks for your thoughts.

I agree that the small pump and loop would be best, but I think too difficult at this point. Here's the situation: bathroom is over a VERY shallow crawl space (used to be about 5" between joist and dirt, but when we gutted the space my DH spent many sweaty days shoveling the CLAY soil out through a hole we cut in the wall. Ugh!) The only access to underneath the floor would be if we removed the tub and cut out the subfloor. Even then, there's only about 18-24" under there.

The supply used to run in the exterior walls, and froze last winter. We (DH) rerouted the supply through the attic space (one story home). He ran it right along the sheetrock, and insulated the cold lines with that grey split stuff against summer condensation. Then he created a sort of "tent" or "tunnel" over both sets of pipes with that aluminum faced bubble-wrap type of insulation. All foamed tightly in place. On top of that is two layers of pink finerglass batt. It's certainly better insulated than it was before.

Pipe is 3/4" PEX.

At the interior bathroom wall, it turns down to supply shut-off valves accessible in the bathtub control panel. From there it runs under the bathroom floor, on the warm side of rigid insulation foamed tightly to the joists.

I actually just got off the phone with a tech guy from one of the tankless on-demand companies. He says that the tankless option is do-able, but we'd need such an upgraded model that it wouldn't be worth it for the 30 seconds or so we'd save waiting. The only place to put it would be in the closet by the shut-offs (since that's the closest access we have). And since there's no way to add it to the sink-only plumbing (I don;t think: see below) it would have to be sized for the GPM the shower demands, otherwise even when it's not heating the water, since the hot water is running through it, it would reduce the flow at the shower too much. Since we have a showerhead AND handshower that sometimes run simultaneously, that would not do. And the higher GPM models are just too pricey. I was thinking I *might* be able to swing $125 or so by next fall if I saved. not $500 certainly. Our bath remodel and some medical emergencies have really drained us, I'm nervous about even buying fuel oil for the rest of the winter!

The only space and access at the vanity itself is a 4" space between the wall and the back of the drawers. The vanity is all drawers, and was custom made, so we can't/won't modify it. I don't imagine any of the cheap heaters are like 3" deep?

So, I will probably have to learn to live with it. Not a huge big deal. The shower and tub take very little time to warm up (higher GPM I guess) so its really the sinks that are the issue. We'll probably just live with it.

Thanks!

Try a recirculating pump under the bathroom sink. We had the same problem in our kitchen years ago. A recirculating pump solved the problem and they don't take up much space at all.

i see only two options:
1/ If you have the space nearby, you can get a medium or small HW tank and plumb it in series so that the larger tank fills it with regular hot water within a few minutes. The new incoming cold-becoming-hot water mixes with the hot water already in this small tank so it has no impact on your hot water at the tap or shower.
-- This small tank is e.g. 2, 4, 5, 6, 10, 20 gal; not IHW boiling hot (open, 1/2 gal.)
Type "10 gallon electric water heater" into a search engine, and see the various shapes these things come in. Plan somehow somewhere to hide it. At Aubuchon I saw one that was 16"round and 24" high. Smaller shapes exist too. To be plumbed in series, they have to be plumbed like all the other regular HW heaters, with pressurized water.

2/ other option is you recirculate which causes hot to be permanently running in the pipes. There are many methods to do this. One of them uses your cold water line to send the lukewarm water back to the water heater tank far away. Yes, this method has some disadvantages, just as every method has disadvantages. This method makes your hot water move slowly enough that it is only warm by the time it reaches the bathroom. It means your two pipes are the only pipes you need. ----Another method is to string a new pipe all the way, which is dumb easy, once you figure out how to send pipe from A to B without climbing into the crawl space. (An insulated pipe, of course.) Or you use the attic.

staceyneil are you in Maine?

Seven month old thread.