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Retrofitting--home run vs 2 pipe
Still planning to retrofit hot water rads into my current house. Seems like everyone here favors doing home runs whenever possible, seemingly for the improved flow control it gives, but I'm trying to understand when and where the advantage of home run over a 2 pipe system just isn't practical. In my situation, my 1800 SF house would need 15 rads on the main floor, and I was considering 3 low temp baseboard units for the 1100 SF walk out basement. That's 36 runs of 1/2 inch pex run along the ceiling of the basement and the ceiling of the garage, since about 800 SF of the first floor are above an unheated garage.
Five of the rads would be above the garage, so to run pex to those, big patches of the garage ceiling would need to be removed, and then replaced after the pex was run. The joist bays above the garage are packed with fiberglass.
The areas above the basement would be easier to pipe of course, but that's still 26 separate pipes running through the basement joists. And a lot of drilling.
It seems to me though that a 2 pipe system, direct or reverse return, would be far less work, use far less pipe, and be far less "in the way" down the road. But I'll defer to the experts. If experience says that the home run system is going to work far better, then I can do it. If the advantage is more of a theoretical one, I'd rather go 2-pipe.
All opinions welcome. Thanks.