I have a hot water heating system with steel fin convection baseboard radiators. I am trying to replace a 4' run of these with a panel radiator that is about 16" wide and 27" high. This is in a very small bathroom (about 25 sqft) that was created by carving up a bigger room, so the 4' baseboard was overkill (left over from the remodel). The heating capacity needed is small.

I want to essentially build a panel radiator out of copper fin tubing. My question is: should I use a series or parallel connection? What I mean by this is should I connect 4 16" sections of fin tubing in series using a zig-zag pattern, or should I run feed and return tubes vertically and run 4 sections equally spaced off these vertical pipes (a parallel connection)?

There is enough pump pressure and the supply lines are 1" diameter. The fin tubing will be 3/4". The original heater has a valve on it, so I assume that the underlying design is somewhat of a home run design since the radiator can be shut off without affecting the rest of the house.

I can't advise on building your own radiator. I just will say that it seems like a lot of work for 25 sq ft, and in linear feet it's more than the 4' baseboard you took out.
I put in panel rads in a large room at the end of a run of rooms with baseboard. It is recommended by the panel manufacturer (Runtal) that it be at the end, I assume because of the smaller diameter.
Were I doing a 5 x 5 seldom used room I would put in an electric recessed wall heater with a timer, or just put the 4' baseboard back if it's part of a run anyway.

I can't put the 4' baseboard back because the space where it will go in the remodeled bathroom is only 20" wide. I have looked at Runtal and Myson products, but they don't quite fit the space. 3 or 4 runs of fin tubing will work nicely and fit in the existing cut out under the window.

The plumbing is such that each radiator on the second floor, where the bathroom is, seems to be on its own feed. This is an 80-year-old house - well made.

All I need to know is what is the best layout to use for my 16" sections of tubing - series or parallel.

I am leaning towards doing them as a parallel connection because this makes for a cleaner grid. However, water circulation won't be equivalent in each of the parallel segments. That might cause problems. Series, on the other hand, means a large heat drop from the beginning to the end.

Some people run baseboard innards under the toe kick of cabinets with a decorative grill.
Unless your window is in the middle open space.
How about one of those tiny cast iron box radiators? Not 27" high, but I think 16 - 18" wide.

Hi Picone

I've worked with the steel fin tube... I understand what you mean when you say, "overkill". The copper fin tubing should work a nice balance in your plan.

I would run this in series. Here, you would just start at the feed pipe (install shutoff) and run the copper fin tubing back and forth on itself until you connect to the return end. Install a key vent (coin vent) at the highest point and that should be all required here... ;)

Questions? Let me know, OK?

Mark

Have you considered simply cutting down the finned tubing and cover to fit the available space?