aluminum plates in an outside wall

Bob Gagnon plumbing and heating

Here in northern Mass. I am worried about freezing, could I get foam sprayed in behind the plates? thanks, Bob Gagnon

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Ken_8

Any insulation is always

better than no insulation.

Options abound:

1) glycol the "plate" tubing.

2) if you can get plates in, why not R-13 too?

3) constant circ. would reduce frost risks.

to name a few...

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Unknown

I assume you're on the inside face of the studs. Why would the freeze risk be any greater than anything else in the room then? Just a piece of drywall difference. it's not like putting a manifold in an outside wall and cutting out half or all the insulation to do it.

and I love extruded plates, but they are overkill for a wall. Use pex-al-pex and lightweight plates and you'll be fine.

Andrew Hagen (ALH)

Antifreeze

I would not use automatic fresh water make-up on a system with anything I was concerned with reaching freezing temperatures. The spray foam is good at making expansion noise with pex. Pex-Al-Pex sounds like a good idea.

Extruded plates may or may not be necessary from a heat transfer standpoint, but something like Thermofin-U could really make the install easier.

-Andrew

hr

Spray foam

give both r value and an excellent infiltration protection, which is more important that the insulation itself many times. For this reason foam makes more sense than fiberglass batts. Foam the bays with tubes in even if the rest of the place has fiberglass or other insulation.

Virtually all new construction in this area uses 6" outside wall framing. Plenty of R value to keep pipes that are in contact with the interior wall from freezing.

There are a number of way you could make just that zome constant circ. A 3 way zone valve is a simple method. Nice to have a bathroom floor and wall warm year 'round.

Some plumbers even install shower valves in outside shower walls, around here! Probably safe unless we have an extended power outage

I like the extruded plates with PAP. You are probably not talking aboiut a lot of square footage, so cost difference between the thin and heavy extruded would be well worth it, I feel.

hot rod

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Bob Gagnon plumbing and heating

why pex al pex?

with the plates? for expansion noise or because it's easier to work with? do you think 2" of ridgid foam in the outside of the wall and 3 1/2" fiberglass on the inside of the wall up against the plates would be O.K.? I'm having a hard time getting someone to spray it. thanks, Bob Gagnon

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hr

Sure

I would still install that 2" foam with some spray can foam. This will "wind proof" the detail and hold it in place. They make different expansion rates of that spray foam now.

I like the PAP for expansion, and because it stays in the shape you bend it to. Less pushing stress on the plate and mounting point.

Some brands of pex with the EVOH on the outside will really squeak when it rubs against itself or in tight holes. You sure don't want that noise and sound amplifier in contact with your walls

I also feel the aluminum layer transfers heat a tad better. And I know my O2 barrier is protected.

hot rod

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Bob Gagnon plumbing and heating

thanks for all your help

once again, I will order a roll of PAP tommorrow. Bob

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jerry scharf_3

I'm worried about energy loss

Bob,

Sorry to be late getting to this.

You are taking your hot water for heating and exposing it to the maximum heat loss location. You will have to consider how much heat makes it into the rooms as compared to out the wall. Even with closed cell polyurethane, there will be a fair amount of loss from the thermal bridging of the studs.

So maximum insulation is a must. Sprayed in closed cell foam is the best. Closed cell foam board with foam to seal it up is probably second. I wouldn't consider much of anything else, certainly R13 fiberglass will not be kind to your wallet or your comfort. First cold and windy night will make it all clear.

jerry