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System Improvements

I have a customer looking to make some improvements to his steam system.  House was built circa 1930 and the system is a mostly originaly two pipe.  Boiler was replaced about 10 years ago.  Currently the majority of the steam traps are failed open and the customer is using the radiator valve to control heat to each room (had three of four radiators shut off upstairs- the fouth in the master they open each evening and shut off each night).  Whenever they go into a room they turn up the valve to heat the room and shut it off when they leave.  We just replaced all three main air vents.  The system now seems to be flooding the boiler slightly.

I'm working a quote for all new traps currently.  What are other good meaningful improvements that should be looked at?

Thanks for the input.


  • sreja
    sreja Member Posts: 175
    re: System Improvements

    TRV's have done wonders to improve the comfort and reduce overheating in our building.  i would recommend them to everyone.
  • Hovlandstech
    Hovlandstech Member Posts: 22

    Do TRV's have any adverse affects on system operation.  If they are constantly adjusting radiators up and down, is it changing how the rest of the home heats drastically?  We don't see much steam around here and most of what I know is off the wall.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    steam improvements

    many 2-pipe systems function best on a pressure of 6 ounces, and therefore a vaporstat would be a great improvement, verified by a low-pressure gauge [gaugestore.com 0-15 ounce]. at the very least a 0-3 psi gauge should be installed to get the pressure down below 2 psi. the traps may have been killed by over-pressure. plenty of main venting is needed to let the air out instead of paying the gas company extra to force it out through the constipated little openings of inadequate main vents!

    also check the boiler piping to make sure that the manufacturer's instructions were followed. post pictures here if you need some more opinions on the install.

    if the water looks dirty, as if the replacement work was never skimmed, you can show the owner how to do that.

    when you describe the slight flooding problem, is this because of an auto-fill over-filling because of slow returns, over-pressure stacking condensate in the returns, or wet steam throwing water up in the main?--nbc
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    edited January 2012

    i think that if you get the steam arriving at all the rads simultaneously, and with functioning traps, that their comfort level will be much higher. so i would leave the trv's for later after the system has been restored. presumably the rads were sized perfectly to the rooms, and do a good job.

    forgot to mention the importance of insulating the pipes which the homeowner could do for himself, with guidance from you.

    maybe you can get new insides for the traps, and make the job easier!--nbc
  • Enreynolds
    Enreynolds Member Posts: 119

    May be another solution to look into.  They worked wonders for my system.  Check out this article.  Ignore the 2 PSI suggestion and listen to nbc's low pressure advice.
  • Hovlandstech
    Hovlandstech Member Posts: 22

    Seems to be auto-fill overfilling from slow returns.  We just changed the three main air vents out (2 were stuck) and have yet to see how that impacts the boiler.  Also, the pressure was originally up at 5psi and I have turned that down to keep the pressure low.  Does have a direct return trap on it, but think that has long since been plugged up/ inoperable.
  • Hovlandstech
    Hovlandstech Member Posts: 22

    Would TRV be useful in a situation where the owner likes to use the radiators as their own personal zoned system?  Is there anything out there that I could zone the system with programmable thermostats?  Seems that is ultimately what this customer is after.  I don't know completely enough to advise against that.  All of the supply piping in the basement is well insulated.
  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    Return Trap

    The return trap is critical to proper operation of a 2-pipe system if the pressure rises much over 1 psi.  In a gravity return, the height of the return piping must be 30" above the boiler water line, for every pound of pressure in the boiler.  So, if the boiler gets up to 2 psi, that means it takes a column of water at least 60" tall in the return piping in order to push the water into the boiler.  If your return piping is less than that, all of the condensate will pile up in the return lines until the boiler shuts off, resulting in possible flooding of the boiler.

    Since you have a return trap, I would recommend servicing it, cleaning up the return lines and flushing them out.  The check valves below the return trap are critical to its proper operation and if their full of sludge, nothing will work.  Sludge in the return piping will also slow down the return of the condensate.

    If the system is controlled with a vaporstat set at 8 oz, then you're looking at a 15" head in the returns, which of course is not a problem.  If you repair the return trap and also install a vaporstat, I guess that could be called a belt and suspenders approach.

    One thing regarding traps, if they are all still pretty much original, you can purchase thermostatic elements for many of those still, and it will save a lot of money.  The thing that you really want to be careful of is having a bunch of different brands of traps on the system as they usually vent air at greatly different rates and will cause the system to become very unbalanced.  This is spoken out of experience. 
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
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