Moving radiators in a converted gravity system

plumb1pa

I've got a customer who wants to move 2nd floor hot water radiators from one room to another. They are fed by a one inch supply and return line (two radiators off one supply and return) can I just cut them out and reroute the piping with 3/4 heatpex? Or do I need to keep the one inch. I'm concerned about flow.
It's an old gravity system that someone else converted I can't see how it works the way the boiler is piped, but he says the heat has been fine. Thanks in advance.

Jamie Hall

If you are concerned about maintaining balance and have no other way to do it, stick with the 1 inch. The difference to 3/4 inch doesn't seem like much, but the latter will have twice the velocity -- and 4 times the head loss.

plumb1pa

Ok, thanks

kcopp

Be careful... Keep the runs the same length as before. Gravity systems can be tricky. Dont trap piping... keep the same pitch as before.

pedmec

agree with jamie. If your adding piping and fittings to move it your also adding head loss to it so reducing size will make it that much worse.