Pipe insulation for hydronics

[all night moe]

Most of my 2nd floor is remodeled. There is no heat. My plan is to install cast iron rads in the rooms. I'm looking to run a loop up through an exterior wall into the attic of 1'' PEX. One each for supply and return. The living room downstairs hasn't been remolded yet, making it easy to do this. There is a closet upstairs sharing the same wall, giving me a strait shot into the attic. I'm not concerned about insulation R-value in the wall. I am looking for the best solution to insulate the attic loop and 3/4'' drop legs to the rads. Each drop leg will have valves at the 1'' loop.

Using 2 loops of the 1'' because I will have thermostatic valves at the rads to regulate temps. I believe this will require the 2 pipe system. So, I am looking for the best cost effective and yet efficient way to insulate. Obviously, I want to keep the heat in the system.

A. Use underground PEX system. Not cost effective. Not even for the cheap stuff. I'm looking at a 300' run or better.
B. Make my own using solid drain tile with insulation of.....
C. Use regular pipe wrap and place the pipe in a foam board boxed run.

Any other ideas or recommendations?

 

[all night moe]

Found this:
https://www.homedepot.com/p/Armafle..._-300891325-_-2-_-n/a-_-n/a-_-n/a-_-n/a-_-n/a

Not sure of the R value but it's "closed cell" and the 1 1/8'' thickness should do fairly well. I'm thinking once I get it all set up and installed i can wrap the assembly with 1'' duct work foil faced insulation. Looking at the 12'' wide stuff, I should be able to get 2 wraps around.

 

[salecker]

When i built my house
The upstairs is when my bedroom is, but i like to sleep in the cold. So i insulated all the walls and upper floor. I ended up insulating all the walls for the lower bedroom as well. I figured with TRV's controlling the cast iron rads that every room could be it's own temperature if the doors were closed.
It works very well
My upstairs stays as cold as i want it, plus the upstairs bathroom is nice and toasty so long as you remember to close the doors.
I have runs of 1/2" pex to and from each rad group, no issues of getting heat when required like an extended stretch of -40 C F temps. The lines run in the insulated walls and floor.

 

[all night moe]

The lines run in the insulated walls and floor.

I thought of this. You benefited from building your house. I bought a mid remodel. The attic has a floor of 1/2'' plywood fastened with ring shanked nails. To me it's not worth the struggle of a 300' run. Even if I just cut strips of the ply out and relayed after.

That's why I'm wanting to keep the PEX external and hung from the rafters close to the floor where they will enter the rooms. Also a small benefit of servicing if the need ever arises. Shut off valves at each room location. Installing valves there because some rooms are not yet remodeled. Some are just currently used for storage. These rooms do not need rads installed yet. With so much to do here, I can add rads to the rooms as needed. The valves will permit me to run the loop and energize. When I add rads it will be simple to just open the valve after hook up.

Good thought for me on using 1/2 PEX to feed the rads instead of 3/4. Then again, the 3/4 will give me a bit more ''storage.'' LOL
Actually I feel it may be easier to flow with so much line in the total system. OWB with 160' of 1 1/4'' to the house. Upon entry, two 2'' copper manifolds. 2 zones, using the OWB's circulator of radiant floor heat. One for the kitchen (this is where the underground lines will enter below), and one for the adjacent mudroom. These are both fairly small zones. On the supply manifold will be 2 more circulators. One for the attic loop and another for the rest of the 1st floor loop, both 1'' PEX.

Well, that's my plan anyway.