Hot Water Recirculating Loop

By Tim Carter
©1993-2010 Tim Carter

Summary: Hot water recirculation creates instant hot water throughout your home. Installing a hot water return loop is fairly simple. Do you have one in your home? Are your builder and plumber the best for the job?

Are you old enough to remember the hilarious candy factory scene in an I Love Lucy episode? I am talking about the one where Lucille Ball was trying to grab candy from off a conveyor belt in a candy factory. The faster she picked off the pieces, the faster the belt turned. Soon she was placing candy in her mouth, her dress, everywhere.

A similar conveyor belt delivers consumers, builders, plumbers and other subcontractors to the marketplace each week. Depending upon the speed of the belt, these people may not have had a chance to gain the needed knowledge to be the best at what they do.

You must be on a slow conveyor belt as you are doing a superb job by reading this column and perhaps other like it to become a savvy consumer. Continue to do that and try to get as much great information as possible as you start to gather facts that will help you build the best possible home. But what about some of the people who will build your new home? Are you sure you will have the best builder and plumber? Here is one way to find out.

Homes that have simple basements often have the furnace and water heater down in this part of the house. It is a great place for this humble but ugly equipment. It just so happens that heat rises and that physical attribute can harnessed so that each time you turn on a hot water faucet in your new home, no matter what time of day or night, you can have hot water within one or two seconds.

But my guess is that you have rarely experienced this in any home you have lived in. Often it can take 10 or even 30 seconds to get hot water to a faucet. If your builder works with a superb and experienced plumber, you can enjoy instant hot water with very little effort and extra expense.

To enjoy instant hot water at all of your faucets, all that has to be done is to install a hot water recirculation loop within your new home. Commercial buildings, hotels, hospitals, etc. all have these things and they are hidden in the walls and ceilings of these large buildings you have visited and possibly work in. You have probably never given a second thought to the fact hot water seems to always be at faucets in these buildings.

How hard is it to install a hot water recirculation loop? It is not hard at all. In fact, over half of the work is already done as the plumber installs water supply lines to each fixture group in your new home.

All a plumber has to do is install a 3/4 inch diameter line from the water heater that feeds all of the fixtures in the house that need hot water. He continues this 3/4 inch pipe throughout the entire house and branches off of it to feed hot water to each fixture.

But when he gets to the farthest fixture away from the water heater, he doesn't stop the line - as most plumbers do. Instead, he continues the 3/4 inch line all the way back to the water heater without interruption. This return line then connects to the bottom of the water heater where the drain valve is located.


For even more tips on how to correctly install a gravity hot water loop, read an additional column I wrote about this topic.

To make the loop work, this 3/4 inch supply line must be insulated as it leaves the water heater and makes it way towards each faucet that gets hot water. The return loop must also be wrapped with insulation after it passes the last faucet in the house and makes its way back towards the heater. But the last 15 feet of the return pipe should have no insulation on it. By allowing the water in this portion of the pipe to cool, Mother Nature sets up a very slow convection flow of water within the loop.

This very slow flow of water by gravity, allows the water within the piping system to stay hot. The insulation on the piping keeps energy usage to a minimum. A portion of this extra cost is often offset by the amount of water you otherwise would have wasted by turning on a faucet and letting water run until it finally runs hot.

Interview your builder and ask him if he knows how to install a gravity recirculating hot water loop. See if he understands the physics of how it works. If he doesn't know or his plumber is in the dark, perhaps you should tell them to jump onto a slower conveyor belt.





Comments:

Denny
17 Dec 2007, 21:19
I was wondering if this would work with a instantaneous heater and a small electric tank for the loop.

Thanks Denny
AsktheBuilder
18 Dec 2007, 08:11
Denny,
It would, but a monster energy waster!
Nathan
03 Jan 2008, 22:29
Any rules of thumb on how much energy the system used keep the loop warm? I have a large house with a 100 foot run and was going though 100 gallons of propane a month. I turn off the recirculation system dropped to 20 gallons. Any ideas?
AsktheBuilder
05 Jan 2008, 07:19
Nathan,
It sounds like your loop is not insulated..... Is that possible? That is an enormous difference. All of the houses I have ever installed insulated loops never saw more than a 3% increase in energy usage for the luxury of having instant hot water.
Rick Davis
05 Jan 2008, 10:09
Can this be added to a hundred year old home? Or should I install a recirculation pump? How would it work with two hot water heaters? We have a hundred year old building that was an old gas station on the ground floor and two apartments on the second floor. We converted the second floor to one living space and moved in about three weeks ago. Then we discovered a good two to three minute delay getting hot water to faucets. And our dishwasher flashes a hot water alert every time we use it as it has to heat the water before it can continue to wash. Any suggestions? Thanks and have a great day.
AsktheBuilder
05 Jan 2008, 10:12
Rick,
Read all of my hot-water loop and pump columns and you will discover your answers.
Rick Davis
05 Jan 2008, 10:45
Thank you wise Master

Grasshopper ;-)
AsktheBuilder
05 Jan 2008, 11:07
You can call me Sensei if you want... :->
Nathan Roberts
06 Jan 2008, 21:58
I think they might not be insulated. I went back to look at the pictures during construction and on the outside wall there was some insulation coming though the stem wall. On all the inside penetrations through the slab there is nothing. I didn't see the plumbing before they cover it over in the ground so I have no way to know for sure what it there. Since the house is a southwestern slab on grade with no basement, single story, what are my options? I could but the pump on a timer and lessen the pain, put it on a motions sensor with the bathroom, I have seen these pumps you put under the sink, or some sort of electric instant hot water under each sink. With Propane running $3 a gallon the $240 extra a month would make any other options good ones.
AsktheBuilder
07 Jan 2008, 06:11
Nathan,
Read my columns about the hot-water pumps that have timers.

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