hot water recirculation retrofit

[mobern1]

It has been recommended that I try this recirculation system with one of my clients.
Do these things work and are there draw-backs to them?
One of our plumbers suggests the Grundfos Comfort System but I have never used one of these systems and do not know anyone personally who has.

[NW Architect]

They work, but you need to pipe a return loop. Hard to justify the cost unless a lot of walls are coming apart for other reasons.

[ajnsue]

i beleive there are two approaches. One is using a dedicated return loop from the most distant point from the water heater. The other uses a loop fitted under the basins that allows standing hot water to be pushed back through the cold water lines. I would think the dedicated loop is the most durable. but defintely more expensive. The Grundfos system if i recall correctly uses the loop back through the cold water line

[emer construction]

I installed that retrofit sustem in my home. It works well, depending on how the house is plumbed. If there are alot of long branch lines, you're still going to have to wait a little for hot water. My Plumbing is run under the slab an goes from one fixture to the next. the bypass is under my furthest sink and I have instant hot water at every fixture.

The only drawbacks I notice are that at the fixture where the bypass is located, the cold water side will be warm, not cold. And that the water heater runs more. Doesn't really bother me.

[ajnsue]

as a side note - with the dedicated return loop I have in my house. You have to recognise that it will improve hot water..performance(?) only on the fixtures directly off that line. If you have a substantial branch off of the main line you will still notice a lag in host water delivery. The hot water is instantaneous to my MB - but the kitchen still has a little wait. Even though it seems physically closer to the water heater (but its off on a branch)

[RJCarney]

Mobern:

We did a job last year using a dedicated return to the farthest shower & vanity, as the homeowner had to wait a whole 30 seconds to get hot water.

We tore open ceilings and walls, installed a pump, and now the wait is about 3 seconds, but a tremendous energy waster - the pump is always on and even though we insulated the lines, the water heater works harder.

But the homeowner is happy!

You could probably use a timer for the pump, but that option wasn't taken in our case.

RJC

[Cornerstone Tim]

It is funny this thread hit right now.

In the past I have installed a circ pump at the heat source with and without a return loop. When I have installed it without a loop it was NOT very effective.

I have to tackle one of these this week on a 6500sf home that is less than a year old. The original plumber did a fantastic job on the waste and vent, but unfortunately fell short on the domestic water engineering. Installing a return loop after the fact, especially in a completed multi-story home is almost impossible without some major modifications.

To correct the issue in my customers home, I am installing one of these http://www.plumbersurplus.com/Prod/L.../23000/Cat/534

I will be glad to share the outcome with anyone after I am finished.

There are three things concerning the domestic water that I always plumb into a new home.
1) Stub outs with valves for future expansion.
2) Drip legs for draining the system if needed.
3) If the farthest fixture is more than 70' of piped feet from the heat source, a return loop on the hot water line with a circulation pump.

[Michael Kingsley]

What about this D'mand system:

http://www.greenerbuilding.org/produ...?cid=54&pid=14

I'm not a plumber and I can't tell how this may be different than the conventional recirculating loop. The advantage with the D'mand seems to be the ability to easily install it in an existing structure.

Does anybody have experience with this product?

Michael

[NW Architect]

The device in post #7 is activated by a timer. There will be hot water at the fixture only if the usage occurs during the time(s) set for the pump to be running.

The device in post #8 is activated by a push button or motion detector at the fixture (it can also be activated by any one of a series of switches at all the fixtures along the plumbing line, if so wired). The user needs to wait a bit for the hot water to circulate before opening the valve. (The very efficient technique known as first you push the button, then you go pee, THEN you wash your face)

[AZ Contractor]

I do restaurants all the time and we always provide hot water loops. We typically install Grundfos recirc pumps with timers and an aquastat.

They are very good systems that are usually engineered with our Rinnai tank-less water heaters.

In restaurants the hot water tap must reach a certain temperature in a specific amount of time. With the Rinnai and Grundfos, we've never had any problems.

I have also just passed my pre-drywall inspection for a custom home in which we have a hot water loop and the Rinnai-Grundfos system. Excellent system.

[emer construction]

I do restaurants all the time and we always provide hot water loops. We typically install Grundfos recirc pumps with timers and an aquastat.

They are very good systems that are usually engineered with our Rinnai tank-less water heaters.

In restaurants the hot water tap must reach a certain temperature in a specific amount of time. With the Rinnai and Grundfos, we've never had any problems.

I have also just passed my pre-drywall inspection for a custom home in which we have a hot water loop and the Rinnai-Grundfos system. Excellent system.

AZ Contractor
How does the system work with a tankless? Wouldn't the water heater be running the whole time?

[Michael Kingsley]

One question I have about these sysytems is their energy efficiency. Although they may save water, isn't there a big heat loss in the loop line, even though you wrap it in foam insulation, requiring more energy for the whole system? For people on well water, there's no $ savings in having the loop, only a convenience, so it becomes more of luxury item that wastes energy.

That's why I was asking about the "D'mand" systems that tout themselves as being more energy efficient. Are they?

Michael

[swbuilder]

Michael,

I think I agree with your assessment. At first when my house was finished this abnormally cold winter, i was extremely dissapointed at the time it takes to get hot water at about 1/2 my fixtures. I cursed my plumber for not bringing up a pump/loop until we were in the finish stage, and I was mad at myself for not knowing any better. In reality though I find that I just have to turn the shower on for a minute or two before I jump in. The increased energy cost of my water lines run in the attic, I think would be substantial with a loop.

Does anyone know of a dedicated fixture heating system I could put under, say the kitchen sink and one of the master sinks for hot water? My trunk line is probably 100 feet.

Randy