New Home - Recirculating Hot Water

[foggy1111]

We are building a new home....and we discussed with the builder our current wait for hot water at our baths. The builder suggested we install a recirculating hot water system for our new hot water system (including 3 baths).

Anyone have some experience with this? I think they use a small pump and a loop to keep hot water available at all times. What kind of energy costs with a set up like this?

[BobRip]

A friend did this. He put the pump on a timer and just ran it for a few minutes in the morning. Be sure to insulate both supply and return pipes. Cost, I am not sure but it would not be trivial. The pipe would be kept hot along its entire length and radiate heat. The timer of course would reduce this significantly and might even save money since instead of sending the partially heated water down the drain to get hot water to your location, you would recirculate it back to the hot water tank.

[JoeBuyer]

Why not just put in instant hot water heaters at the more remote faucets?

[jinman]

As JoeBuyer recommends, I'd think about a tankless water heater. It should be cheaper in the long run than circulation of water and trying to insulate piping. You'll have to have a 60A supply for this unit by Rheem, but at $228 with the elimination of the need for long hot water runs of piping, it should pay for itself and the electrical power wiring in short order. This unit is small enough to put in the wall between studs and cover with an access panel.

[EddieWalker]

I've seen and been asked to work on some of those instant hot water heater systems. It's not something I'm familiar with, so I pass on those jobs. I don't know how many are out there, or how many have issues, but with a couple of calls a year about them, I'm not going to put one in myself. Instead, on the house I'm building and on mine, I put the water heater fairly close to my bathroom. It takes less then a minute to get hot water in my house and it will be the same for the house I'm building my parents.

Lots of houses have two water heaters. Check what the price difference is, and what your ussage is, but rembember the lifespan of what you install and what it will take to keep it working all the time.

Eddie

[aczlan]

I setup a thermosyphon loop on our hot water heater which keeps the water at the end of the loop (~50' away via 3/4" copper) toasty warm.
It took ~$20 in parts and some thinking to make it work, but it didn't require a pump or any electronics and only has one moving part (a swing check valve).
It will only work if the hot water heater is below the hot water lines. I based it on a diagram that the furnace guy wrote on a box .

Aaron Z

[nybirdman]

The three pipe domestic system is the "standard"for commercial type systems,I.E schools ,hospitals and office buildings.
Your builder is correct,use this if you have long runs for domestic hot water.Cost effective;once the system is brought up to temperature and well insulated;minimal.Today's circulating pumps draw little power.If you don't use this type of system a lot of water is wasted waiting for hot water.

[psj12]

I bought one of the single point instant hot water heaters to use for a washing machine at our vacation site where I have a washing machine in a barn. The heater was sold on E-bay as a "Whole House Instant Water Heater". It barely worked for just the washing machine and draws 60 Amps of 220 volt. That's as much as an electric stove with all burners and the oven on. Even then I had to throttle back on the flow rate to achive hot water.

It was better than installing a tank but I would not outfit my house with such an energy hog. I realize there are better gas fired instant systems that are more effecient.

[s219]

We're building a new place too, and the builder spec'd a recirculating pump into the plans. It's actually fairly cheap. I have some concerns about continuously circulating hot water around the whole house, and will discuss it with the plumber at rough-in. If we're just going to be circulating hot water around a loop all day long so it can cool off and return to the tank, requiring the tank to heat more often, I would pass. On the other hand, if they can keep it well insulated to minimize the heat loss, this type of system would make my wife very happy.

[aczlan]

We're building a new place too, and the builder spec'd a recirculating pump into the plans. It's actually fairly cheap. I have some concerns about continuously circulating hot water around the whole house, and will discuss it with the plumber at rough-in. If we're just going to be circulating hot water around a loop all day long so it can cool off and return to the tank, requiring the tank to heat more often, I would pass. On the other hand, if they can keep it well insulated to minimize the heat loss, this type of system would make my wife very happy.

If the HW lines are in the basement ceiling and the HW heater is below them, IMO a pump is optional (and having dealt with pumps dieing in a hotel hot water recirculation system, I would prefer to avoid them).
Below is how my system is configured:


Aaron Z