Vapor system questions

culdog

Hi Folks this is my first post so please be gentle. I'm a plumber up in the Boston area about to help a friend with an old vapor system. I haven't done many steam boilers to begin with and never a vapor setup. Basically I'm tackling a quagmire.The house itself is a big old Colonial that HAD a 2 pipe vapor steam system, I say had because some radiators have the old ball and elbow elements (not sure exactly what the're called), and some have therm. traps. The boiler is an oil fired Weil McLean installed about 25 years ago, it has a pressuretrole that never reaches 1 lb. The whole system heats terribly. I guess some of my main questions are Can this system be converted to a modern gas fired 2 pipe steam using thermo. traps? My buddy is against installing forced HW because of so much remodelling involved.Any help will be greatly appreciated

Joe V_2

Sure.

I did mine.  Look at it sysematically.  Some of the biggest offenders that cause terrible heating are:

Improper near boiler piping

Bad or inadequate Main venting

Bad or missing steam traps at radiators

Over sized boilers.

Lack of pipe inulation.

Vapor steam heating should be supreme to other forms of heating, quiet, efficient, and very comfortable. 

culdog

Vapor system questions

Thanks Joe V. for the quick reply. Your near piping statement leads me to ask if using a drop header is ok here?

Jamie Hall

Joe V

seems to have hit the high points.



Vapour systems do, however, benefit from intelligent contemplation, and a somewhat leisurely approach.



First off, you can indeed switch to a modern gas fired boiler as your heat source.  No problem at all.  Furthermore, piping it with a drop header is a very good idea indeed.  Main things with making that replacement are first, to install that new boiler so that the new water line is within an inch or two of the old water line.  You may find that you need to raise it on blocks to do that, but it really is important.  All sorts of very odd things can happen out in the system if you don't!  Second is to follow the manufacturer's instructions as to number of risers and sizes of risers and the rest of the near boiler piping -- but to take them as minimums.



Then... install a vapourstat to control the system.  Costs a little more, but it's worth it -- particularly with the type of outlet controls (ball and elbow) which you have on some of the radiators.  They simply don't work right at much over 12 ounces pressure.



Venting can be a bit odd on vapour systems, and it is rather important to do it right.  Many (not all!) vapour systems depend on crossover traps at the ends of the steam mains.  These are thermostatic traps, just like a radiator trap, but installed above the steam main and dry return (you go up and over 90 into the inlet of the trap, then down from the outlet of the trap to the dry return).  These work splendidly well, assuming they are working at all -- and it's well worth checking them.  If that is your setup, there will be main venting on the dry return(s) right near the boiler (there will be anyway) but no main vents on the steam mains -- the crossover traps do the job.  The main venting must be good sized; it's venting everything.



Check all your radiator traps and radiator control outlet elements.  Some may need replacement.  Water and air should get by -- but steam never should.  You can replace the ball and elbow units if you need to, but you may not need to.



Boiler size as Joe noted is important.  Size it based on the total EDR of the connected radiation, not on building heat loss or anything else.



Pipe insulation is also important -- insulate everything you can.



And follow up with more questions or thoughts as you get into the project!

Joe V_2

Yes

I installed one on mine.  The bigger, the better to slow steam down and send out dry steam.  There are many photos on this board of nice looking headers. 

Fizz

Do you know who was manufacturer

of system?  As Jamie stated, not all vapor systems have crossover trap at end of mains.  I am home owner and have a Richardson System which has ball in elbow as you describe, with levered supply valves on each radiator.  When I first took over home, some rads added-on had traditional traps and packless valves, but they also had air vents and didn't work so well.  Removed air vents and throttled-back valves, now they work fine and traps are rarely used except on long-run sub-zero or near zero days.  By the way, the only reason I did what I did is because of the fine folks, pros and knowlegeable steamies, who provided insight.  Also added vaporstat.  Good luck with your job! 

culdog

Richardson traps

Hey Fizz, the older traps are indeed Richardson, is that an indication that the whole system was by Richardson?

Fizz

You have a Richardson

System.  The supply valves should be graduated,  packless, operated by levers.  The system is vented solely by an air expeller at the end of the air return line and is usually located above the boiler.  A great resource is here on this site.  Click on Resouces above, then Library, then Old steam heating systems.  All the steam systems from years ago, including Richardson are described with tecnical data.  Good luck!

JStar

Richardson

We work on a few Richardson systems. They are very simple and make for a very nice system. An absolute MUST is to operate at 5oz of pressure or less. A 2-stage gas valve would be perfect for this system as well. If the original pistol-shaped air eliminator is still there, there's a chance that you can maintain vacuum as well. Lucky homeowners!