sizing a distribution manifold

roundrightfarm

I'm install a boiler with home run distribution, going to 23 radiators, all with TRVs. I'm look at two 13 outlet manifolds. I have the option of 1" or 1 1/4". The price difference is minimal. Design heat loss is 141k BTUH, giving me a flow of 14 GPM at design conditions (delta T = 20), or 7 GPM through each, assuming they are well balanced. So 1" seems more than adequate for my flow, but given that 1 1/4" is basically the same price, are there any other considerations that would make me choose one or the other?

hot_rod

I don't know what brand you are considering, sometimes only the connection or ball valve on the end changes, same manifold dimension really. So the 1" should cover your load of 7 gpm.

Branches are usually good for up to 2 gpm, will that cover your largest radiator?

roundrightfarm

Thanks hot rod. I'm looking at Caleffi. Do know if it is the case with these that only the connection threads are different?

My largest radiators should have a flow around 1GPM

hot_rod

Correct, manifold is identical, just the valves on the end change. The manifolds are unique with a recess for the tubes to lay in, plenty of flow with the square shape.

roundrightfarm

thanks hot rod for clearing that up