Should I replace these radiators?

andrewg

I am remodeling a kitchen, and I would like to know if I should keep or replace three radiators. My steam system is a one-pipe steam system, but it has several of these baseboard two-pipe radiators that are fed using copper pipes from the steam mains. They are all on the first-floor of the house. Our local plumber told me these radiators are really for a hot-water system, but somehow they were made to work on this steam system. They make minor water-hammer noises, but other than that, they work fine. I've attached pictures of them.

The room is 11' by 25', and as part of the remodeling we will be adding foam insulation to the walls and ceiling.

Thanks for your help,
AHG

Fred

If it were me, I'd replace them with Cast iron radiators since you are remodeling. At some point the joints on the copper pipe will begin to fail as a result of expansion/contraction. How do they drain back to the boiler? is there a drain pipe under the side that has the vent on it? If so, you may be able to silence the hammer by pitching them towards the drain pipe. They are probably holding some water.
If they work and you can get them pitched so they are quiet, you can bide your time until the copper joints start to leak and make a decision at that point but you've got things opened up now, so this is a convenient time to make a decision.

KC_Jones

Are the convectors copper or just the pipes leading up to them?

andrewg

Thanks Fred, I am inclined to go with cast iron radiators too.

Fred said:

How do they drain back to the boiler? is there a drain pipe under the side that has the vent on it?

There is a pipe under the side with the vent that connects to the wet return pipe back to the boiler.

KC_Jones said:

Are the convectors copper or just the pipes leading up to them?

Just the pipes leading up to them.

KC_Jones

If the convector itself is steel or cast iron it shouldn't be a problem...the copper pipe is more of an issue than anything. Not sure about the piping set up though...possibly a pro or someone with more experience with these could chime in. Possibly hooked up by someone who wasn't sure what they were doing? Not sure about this particular style, but convectors are used on steam it's not exclusive to hot water systems. They just perform very differently from cast iron radiators due to a lack of mass.

Dave0176

I don't see why they couldn't work properly if installed correctly. As long as their pitched toward the outlet and do drop straight into a wet return they shouldnt make any noise at all.

Jamie Hall

They can be used for steam, as has been said. However... pitch is really critical. First, the convector itself must be pitched so that it can drain to the outlet which you say goes to a wet return, and it must really truly drain. It isn't quite clear to me, but it almost looks as though the centre of the three pipes through the convector in the centre picture may not be able to drain completely. That needs to be checked. Second, the pipe to the vent needs to be pitched to drain back to the outlet -- shouldn't be a problem, but it's worth checking. Third, the line to the radiator from the steam main needs to pitch back to the steam main. Fourth, the line to the wet return needs to pitch (preferably drop!) to the wet return.

Furthermore, those pitches need to be held whether the piping and convector are hot or cold -- and with copper that can be a bit of a problem.

Be sure that the noise you are hearing is really a water hammer, though, and not an expansion noise. Again, with copper expansion is rather large, and the pipes and convector need to be able to move with the expansion.

Get it right, though, and it should work quite nicely.

andrewg

Thanks Jamie, that is good advice. We finished the renovation and kept the two convectors. I switched out the copper piping and made the pitch a little more significant. However, the steam main and wet return pipes are in a crawl space below the room, so the return pipe doesn't run straight down. As a matter of fact, the steam main does a U-turn and becomes the return line as it goes back to the basement.
When we first hooked the convectors back up, they didn't fully heat up - there were cold sections in the unit. The plumber thought that steam might be entering the convector through both pipes, trapping air in the middle. He added steam traps and now the units heat up properly. This was at the end of the heating season so we'll have to monitor them when winter returns.

Thanks again for all the advice.