Saving hot water with a Heat Trap? Anti-Thermosyphoning
 

http://www.comfort-calc.net/pictures...sulation_2.JPG

I've seen a few examples of this idea on the web. The hot water output is looped down (or up then down)
to trap hot water in the water heater and keep it from slowly flowing upwards from the heater to the pipes above it.

I'm thinking of using the double loop version when I do my new mixer install..

http://www.energycodes.gov/moodle/fi...ter_Heater.jpg

http://www.energycodes.gov/moodle/mo...iew.php?id=109


Since it's going to be PEX and not copper, not much cost involved..

What do you guys think? Good idea?

Thanks,
Rich

Looks good to me.

Is that enough to keep hot water form escaping from the tank? I thought it had to go back down to at least mid-tank before going up again.

It seems like the loops don't have to be below the tank..
http://resourcecenter.pnl.gov/cocoon...s/full/208.jpg
It looks like the in-&-out lines on this one are from the wall behind the water heater..


My hot water comes from a coil inside of my heating boiler..

http://www.woodboilers.com/admin/upl...sssection2.jpg

the In-&-Out is off the left, top rear of the boiler. So, I can add some heat trap loops
below the I/O and mount the new mixer above the top lid..

Does anyone have any ideas how how big the trap should be? I'd like to do a quick and easy retrofit on my hot water heater with some PEX line.

I believe most of the newer heaters already have heat traps built into them (the 1994 model I just removed did). If yours doesn't, you can buy them at HomeDepot: Camco No. 1015 In. Heat Trap Dielectric Nipple - 15132 at The Home Depot

From looking at the pictures on the web, I don't think the loops have to be very big.

Energy Savers: Insulate Your Water Heater Tank for Energy Savings

The nice thing about PEX is the price.. So, you can use 6" loops are 18" loops
and the price will be almost the same.
Even with the cost of the extra pipe insulation tossed in..

When I do mine, I'm going to try for about 8" and use the 'feel' test to make sure it's enough.

Interesting. How do those work?

I'd imagine the better your pipe insulation, the larger the loops need to be as the conduction of heat through the water will allow the heat to travel farther 'down'.

From what I've seen, they are just check-valves. One-way flow, so the water
can't back-flow..

Before you install anything, you need to test your input & output pipes to see
if they are indeed warming up.. If they aren't, you can forget this project..