Runtal. Hands down.

Thank you. Just to clarify, do you mean that Runtal heats better, hands down?

I have both and I'd say the Runtal can heat better only because you can stack more of them and they look nicer, but of course it'll be pretty costly. But unless you're willing to get more of them, I'd say the Runtal doesn't heat any better than the cast iron. That's my experience tho.

It's more controllable, faster, warmer, and non dependent on supply issues from the pipes. Superior in every way.

Is it a Base-Ray? What is the size of the powder room? You need to do a BTU calculation for the powder room then compare it to the BTU output of the radiator.

The current radiator is the powder room is a 24” Base-Ray. The powder room is always cold in the winter as it appears to be an addition or a porch conversion and only has a crawl space under it. The room has a large window and is next to the back door and entryway which also contribute to the cold. I will do the BTU calculation. Thanks

Do you have steam or hot water? Below is the estimated BTU/ft for the Base-Ray:

Once you calculate the BTU needed for the powder room you will have some idea if going to 48” will be adequate. Also, note that the connection for the Runtal is 1/2” pipe.

Never mix cast iron and any other kind of radiator/baseboard. You'll never get them to heat correctly. Runtal is heat fast/cool fast; cast iron is heat slow/cool slow. Every HVAC contractor knows not to mix this stuff.

Hmm, I belive you are thinking of the copper fin tube (Slant Fin) baseboard which cannot be mixed with cast iron radiators. Runtal specifically says it’s product can be used as a direct replacement for cast iron baseboard. The OP can call Runtal directly (I’ve found them extremely helpful - we are using Runtal panels in two bathroom renovations). You are correct, the OP should also check with a heating specialist. In our area at least, HVAC companies do not deal with steam or hot water heat - you need a plumber who specializes in this type of heating.

Thanks for the help! I will call Runtal. I’m wondering if someone has experience with having installed a Runtal radiator in one room and the regular cast iron radiators in the other rooms.