It seems like PEX is becoming more popular. I keep seeing articles that advise using it with a “home run” manifold that allows for branch plumbing circuits much like branch electrical circuits. Supposedly, this reduces the amount of cold water that needs to be flushed from the system when a hot water fixture is activated, thus increasing efficiency by reducing the cumulative energy needs of the water heater. I find this a bit curious since I’ve never heard of copper or cpvc manifolds being used in residential installations. I wouldn’t think that heat loss would factor into this since copper is likely to conduct heat much more readily than plastics. So why would manifolds be recommended for PEX plumbing but not other applications?
Just curious.
Michael
New knowledge is priceless.
Used knowledge is even more valuable.
Replies
because they are available as a ready made system, and with PEX, you are supposed to use different sized lines. Not just the standard 1/2" supplies. Using 3/8" to toilets and vanities etc. in conjunction with a manifold system reduces wasted water.
rnsykes-I've read the same info on using smaller diameter lines for vanities, toilets, etc. I understand why a 3/8ths line may lead to less wasted hot water since not as much is sitting in the line to cool and it will take less gallons to bring fresh hot water to a sink. However I don't get why cold water supplies such as on a toilet would be more efficient with a smaller line. I would think sizing a line on a home run system would be less critical than on the old series connection of lines.Also, I'm thinking that cupful of water sitting in the copper manifold cooling off is probably inconsequencial.Maybe its just one of those mysteries of the universe.
I agree that it doesn't make sense for tiolets and other cold water sources. You are also correct on the copper cunducting heat, therefore it will loose heat much faster. I think the plastic is a better insulator.
The main advantage of PEX is the installation labor - it's quick. This makes it easy to do home runs, which necessitates manifolds. As Msykes pints out, that also lets you size the lines to the application as well.
Ahh...
You guys are a never-ending source of enlightenment. Thanks much.
Michael New knowledge is priceless.
Used knowledge is even more valuable.
uponor (wisbro), manufacture of pex products has a new line of synthetic manifolds, and also recomends remote manifolds closer to the end use such as all colds to bath.