Upgrading a 2 pipe system

You are going to have a good time!

and save yourself a bundle of cash by the time you get done!

First off, buy yourself Dan's books on steam heat (available right here on this site!).  They are worth their weight in gold...

But there are several things to do or look at while you are waiting for them to come.

If, in fact, there are no traps on any of the radiators, the chances are you have one of the various vapour systems which didn't need traps (there are some which did, too).  First thing to do is to check the pressure at which your boiler is running: on any vapour system (traps or no traps) the "cutout" pressure should not be more than 8 to 12 ounces per square inch pressure (that's ounces, not pounds!).  It is unlikely that the gauge on your boiler will read that accurately, but you must keep that gauge; it's required by code.  If you are fortunate, the boiler pressure is controlled by a "vapourstat", which works well at low pressures; otherwise, it will be a pressurestat, which doesn't.  For the time being, if it's a pressurestat, set it to about 1 pound cutout and live with it.  Until you have read the books!!!

Second, if it is one of the systems which does not have traps, be very careful about fiddling with valves.  Those systems came in two flavours: some controlled the amount of steam in a radiator with an orifice on the outlet elbow, but a number of them controlled the steam with a calibrated valve or orifice on the INLET side.  Changing that valve or orifice can have lamentable results.  If, when the system has been running for a while, the radiators are pretty well hot all across, but the return pipes are only warm (they might be quite warm, as in hot water warm, but not yeeouch wam!), you are probably in decent shape regarding control of steam to the radiators (I'll get back to too hot).

Third, check the venting.  Somewhere on the steam mains (and the returns) you have to have main vents.  They allow air out when the system starts up, but not steam.  If you do not have vents, or have inadequate vents, the system won't heat evenly no matter what you do to it.  Take a look and see what you have, then get back to us on it.  You may very well have to put in bigger or more vents.

Once you are sure that the venting is good, and the pressure is right, and the radiators all get hot pretty evenly, then you can being to think about cooling off the bedrooms (or heating up the downstairs, which amounts to the same thing in the end).  But first things first here...

And let us know how it goes!

Sounds like it might be a Tudor system

unless there's something like a water seal inside those return ells or the bushings they're screwed into. Any strange-looking devices in the piping around the boiler? Any names on the original radiator shutoffs? Can we get some pics? Where is the job located? 

That inlet valve

looks like a newer type without orificing capability, it was probably replaced at some point. Are there any others that look much older?



The return elbow in the pic is for a hot-water system, it has a built-in flow adjuster. Again, are there any originals still in place?

If that one is any indication

You have two possibilities: 1- there is a water seal in the eccentric bushing at the radiator outlet, or 2- there is nothing in the return connections at all. #2 is the more likely.



My guess is that you have what we call a "vernacular" Vapor system, which was something put together by a local practitioner out of whatever parts he could get. Most of the ones we've seen did not use traps or water seals. As long as the local guy had some idea of how Vapor works, these systems were fine.



Start with a Vaporstat at the boiler instead of a Pressuretrol. Keep the pressure at a half-pound or less, tweaking it until little or no steam appears in the dry returns. This will minimize the chances of banging.



If you can't keep steam out of the dry returns, you can install orificing valves on the radiators. These are still available from Barnes & Jones or MEPCO, and allow fine-tuning of each radiator with an adjusting screw while still allowing you to shut off or turn the radiator down with the handle. Alternatively, you could use orifice plates with the present valves, but you'd have to drill them out to the proper size.



When you're finished, you'll have a fine example of a system that has the fewest moving parts possible.