Reducing from 3/4 to 1/2

kensheets2

Hello
I have installed a 3/4" 2 pipe reverse configuration for old cast iron radiators in a 2 story residential, completely new installation. each floor it's own loop.
question is cuz the pipe is so difficult to work with and I did not install it in a manner that would have made it easy to tee off of, would it be acceptable to tee off with 1/2" at each radiator from the 3/4 supply/return lines? also is it a issue to reduce to half inch at manifold?
thanks
ken

mattmia2

Notching the top/bottom of a joist is a big issue.

kensheets2

yes agreed, this is 1910 construction and I sistered up 2x6 against original bowed 2x8 to just level floor and give it a bit more strength, so those holes locations aren't really a problem in this case.

Jamie Hall

Well, actually those holes in those locations are a problem. Holes in moment beams are restricted to the middle third of the beam. Anywhere else in the depth of the beam and the carrying capacity of the beam is reduced in the ratio of the square of the depth of the beam less the depth of the holes to the square of the depth of the undamaged beam. So, for example, a 1 inch hole in the top third of a 2 x 6 will, very roughly, reduce its capacity by the ratio 25/36, or even more roughly, two thirds.

Even one hole will do this!

HVACNUT

Can you draw what you mean to do?
You want to split the loop to install another radiator and make that split at an existing one?

kensheets2

just need to know if it's a problem to reduce to 1/2 out of the 3/4" sup/ret lines as shown in pic

thanks
ken

Zman

Unless your radiator needs more btu's than the pipe can carry it should not be a problem. Would need more info to answer that question.