Replace H/W Radiator with Baseboard Heat Question

Tboans

I have a house that has a one pipe hot water system. I want to replace the Cast Iron radiators with baseboard heaters. Do I have to replace the feed and return pipes? How do I determine the length of baseboard that will be used? I have used the slantfin heat loss calculator, but the numbers look to be too low. They are saying to replace an 5 foot section of radiator with 8 feet of baseboard. If I were to "unlooop"the radiator, the tubing would extend about 30+ feet. I am not expecting to need 30 feet of baseboard, but I assumed it would need more than 8 feet.

I know my return lines will be in a different location, so will I have to move the return line connection to the main or can I just tie the PEX back into the return near the main? Whould I be better off changing this to a loop system?

A.J.

Do not mix

T do not mix cast iron and copper thin tube on the same zone hey have different cycle rates. The room with copper will always run colder!

Tboans

I didn't know about the cycle rates. i know you shouldn't mix baseboard and radiators, but can i seperate them into seperate zones on the same furnace. If i keep the 2nd floor cast iron rads and make it a seperate zone, can I cap off the feeds/returns for the first floor and make it a baseboard loop? have the 2 returns meet right before the circulator pump and then have 2 zone valves. how will that work?

tim smith

changing radiators

If you want to make zones, you will have to repipe at the boiler to allow for boiler protections. ie primary/secondary piping. Then yes you could have one floor of cast iron and one of baseboard. PS Rather than baseboard fin tube, look at Runtal UF series steel rads. Quiter w/ better output in same dimension and also look quite a bit better. Closer to cast temps also than fin tube. Good luck, Tim