Help with one-pipe boiler heating system

Fus1982

Hello,

I'm looking to add a section of baseboard to a small addition that was added on by the previous homeowner years ago. I have a single story ranch with a full basement. The heating zone is a one-pipe/monoflo system that is fed with a 1" pipe and then hits a 1"-1"-1/2" monoflo that feeds the baseboards above. My question may be dumb, but here it is... In this particular zone, all baseboards are cast iron (some other zones have fin tubes). I'm looking to add about 16' of fin tube baseboard to this added room. The fin tube has a 3/4" pipe running through it, so should I install a 1"-1"-3/4" monoflo? The existing rooms with fin tube baseboard have 1/2" branches off the monoflos, but also have the 3/4" pipe running through the baseboard.

One other question while I'm here.. I noticed that the monoflo is at the feed side of the baseboards, and just a regular tee on the return side which I'm assuming is correct and is what I should do here?

What should I do? I may have butchered some of the terminology here, so forgive me. Thanks!

EBEBRATT-Ed

Normally a monoflow tee is installed on the baseboard return and a regular tee is put on the supply.

But it will work with the monoflow on the supply and a regular tee on the return as long as the monoflow tee is in the correct orientation.

If your heat loss for this room is 15,000 btus or less (about 27' of total baseboard) then 1/2" copper should be ok. Anything over that should be 3/4"

The reason you have 3/4 baseboard on 1/2" Monoflo system is that 3/4 baseboard is much more common....and the supply houses only want to stock 1 size. 1/2" fin tube is available but most do not stock it.

The monoflow tees and regular tees are sized based on the room heat loss and the btus of the baseboard connected to it.

bburd

If the other radiators on that zone are cast iron baseboard, you would be wise to use the same for your addition. Cast iron has a much higher thermal mass than fin tube. If you mix the two types in one zone, the rooms with fin tube will tend to underheat.

Since additions are often built and insulated differently from the main building and have a different heating load profile, it's usually best to put them on their own zone. In that case you could use fin tube in the addition.