I have two specific questions regarding efficient home-run plumbing design
My wife and I are currently working with a local design/builder on a set of plans for a small home in Silver City, NM (4B). The main bathroom, mechanical room and kitchen are all grouped together on the 850 square ft main floor. A second bathroom, located directly above the main bathroom, is planned for the 550 square ft loft. The wall assembly will be 2*6, dense pack cellulose, 1 inch of EPS exterior the sheathing, and fiber-cement siding.
I’ve found a lot of good information on GBA on the topic of domestic hot water heating and efficient plumbing system design. We have decided to spec a 50 gal Marathon electric water heater, being that our plan includes PV. If I were to choose right now, I would spec a home-run plumbing system using Uponer AquaPEX tubing and ProPEX expansion fittings.
My questions:
1) If we were to include manifold/ball valve assemblies, would there be any reason to include shut-off valves at the fixtures?
2) The PEX tubing will mostly travel through interior walls and floor joists between the main floor and loft, both of which will be insulated for soundproofing. There will be at least one pipe run through an exterior wall (cannot be avoided). Is there any reason to use closed-cell foam pipe insulation when the PEX tubing is located in insulated wall and floor cavities?
Thanks,
Aaron
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Replies
Aaron,
It's always a good idea to check with a plumber to make sure that your plumbing plan complies with local codes.
Q. "If we were to include manifold/ball valve assemblies, would there be any reason to include shut-off valves at the fixtures?"
A. Yes. The shut offs at the fixtures (for example, in the vanity under a lavatory) allow a homeowner to shut off the water flow in an emergency. Many homeowners may not know where the manifold is -- but they often know to look for a shut-off near the fixture.
Q. "The PEX tubing will mostly travel through interior walls and floor joists between the main floor and loft, both of which will be insulated for soundproofing. There will be at least one pipe run through an exterior wall (cannot be avoided). Is there any reason to use closed-cell foam pipe insulation when the PEX tubing is located in insulated wall and floor cavities?"
A. I'm not a fan of locating plumbing pipes in exterior walls. But if you have to do so, it's important to keep the pipe or tubing uninsulated. You want the tubing to have access to the heat on the interior side of the wall assembly. Keep the tubing close to the interior side of the stud bay (but not so close that the tubing is at risk of being penetrated by drywall screws). Insulate the space between the tubing and the exterior wall sheathing with rigid foam or spray foam. Install this foam insulation with attention to airtightness. The space on either side of the tubing, and between the tubing and the drywall, should be uninsulated, so that the heat from the home can keep the tubing warm.
-- Martin Holladay