I grew up in a house which had a single pipe steam radiators, but my knowledge in limited.

My understanding is the variable vent allows you to control the speed of which the radiator will become hot from one end to the other. The idea is a big radiator has more air which must be evacuated versus a small radiator. The variable vent allows you to have all the radiators heat up at the same time. I am not sure how effective this will be with your situation. The valve is easy to install so you may want to try this.

I have no experience with the thermostatic valves. I saw a This Old House video where Rich Trethewey installed one on a radiator.

Have you tried turning off the radiators in the rooms which are too warm? You may get enough heat from the surrounding rooms and piping.

Do you have a smaller radiator in another part of the house which you can swap with the radiators in the warm rooms? This is a way of balancing the heat distribution.

Radiator covers will also block some about of heat. They usually are custom made and expensive, but it is something to consider.

Thanks for the reply. Already have the VariValves installed. They just don't seem to have any effect, although my plumber had expected they would. Shutting the radiators off entirely might work, but the thermostatic valves mentioned on TOH sound pretty good. Just looking for any feedback on them.

goto www.thisoldhouse.com and click on Heating

or

http://www.thisoldhouse.com/toh/video/0,,20258687,00.html