I have never heard of this hot water recirculating system before, but I am interested. We live in a two story colonial with a basement. The water heater is on the far wall opposite of our master bathroom.

The hot water at the kitchen sink takes a good minute to get hot and the hot water at our shower/tub in the master bath probably takes a good two minutes.

I'm not really concerned about wasting water (we have a well), but it is annoying to go to use the hot water and having to wait, especially at the kitchen sink.

Our water heater is electric, so am concerned if this would make our energy bill sky rocket -- though we would probably lower the usage of our well pump if we don't run the shower for an extra 3 minutes before every time we use it (and I know well pumps use a lot of juice).

Any thoughts?

You install the pump at the water heater, and small valve at the hot/cold supplies of your furthest plumbing fixture (which in your case sounds like the master bath sink.)

When the valve at the master sink senses that the hot water in the pipes has cooled, it will pull the warm water back to the water heater via the cold water supply, thereby re-filling the hot water pipes with hot supply from the heater. (Sorry, this is confusing to write out.)

The upside is that you will always have hot water house-wide. The downside is at the master sink, where the cold water will sometimes be lukewarm. We decided that this is a small price to pay for having quick hot water at all times.

Edit to add: The pump has a timer, so it doesn't have to operate 24/7. If you use it for peak times (mornings and evenings) it will use less juice from water heater.

....hot water supply systems are usually built as a straight line run from the water heater to the nearest fixture to the next fixture.....so on and so forth, until they end at the furthest fixture from the water heater.

If you make the system a loop by installing a small (usually 1/4" or 3/8") line back from the furthest fixture to the water heater, you can keep a small amount of hot water constantly circulating through the line.

There are two methods for this. The gravity method works if you have a significant elevation change between the water heater and the last fixture (for exxample, WH is in basement, last fixture is on the 2nd floor). Because hot water is less dense than cold water, gravity will keep a constant flow of hot water rising in the line, and the colder water will travel back down through the re-circ loop.

If there isn't enough elevation change for gravity to do the work, a mechanical pump can be installed to do the same thing, with a thermostatic valve that activates the pump when the water at the last fixture cools.

As voidoid noted, this doesn't waste water, it wastes a small amount of energy heating water that may not be used at that time. But becasue the recirc line is ususally small, there is very little water being reheated.

would be a lot less invasive/expensive to install than a line though, right?

Our master bath is on the second floor, farthest from the water heater (which is in the basement), so plenty of gravity drop. But seems like running a line from there back to the heater would be quite the ordeal.

Building a home from scratch, you would do the loop. When we remodeled, the pump was like $300 installed versus running the new loop line under slab, through walls, etc.

The valve doesn't dump water down the drain, it recirculates it through the recirc line.

Dumping it would waste water and energy, and is likely not allowed.

It's hard to say exacty how tough it would be to run the line. If you have a plumbing stack to follow, you might only need to cut a couple of holes in the walls in a couple of places to drill a new hole through the sill plates/heads. You can fish a 1/4" or 3/8" copper line through a stud cavity pretty easily.

We installed it at my house, works great, no loop required.

The original pump linked, the Watts 500800, says installation simply requires installing in the pump in the line and sensor by the furthest fixture.

I wholeheartedly recommend it. During the dead of winter it is AMAZING to have immediate hot water.

even existed.

but am concerned about using a ton of electricity for my water heater. Sounds like an interesting system though...I'm intrigued.