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AS Boiler (G-606) Pressure Control/Thermo.Rad.TrapTesting

Joe Grosso
Joe Grosso Member Posts: 307
a version of Vapor which has to be limited to about 8 ounces max pressure. This is because, as you observed, there is no Return Trap on this system to allow the water to return to an over-pressurized boiler. The best pressure control for this is a Vaporstat, get the version that cannot be set higher than 1 PSI.

Tempilsticks are nice, but there's an easier way to look for bad traps: Just feel the dry (overhead) return line. There should be no steam in this line if the traps are working. Dunham still exists as part of MEPCO so original-equipment parts for those traps are still available. It might be best to just rebuild all the traps since they're all the same age- if several are malfunctioning now they all will eventually.

You may need to add venting capacity to the steam mains however. The "crossover traps" on the ends of the steam mains simply route air from the steam main into the dry return, from which it vents thru the air eliminator. In the coal-fired days their size wasn't as critical as now, since a coal fire burned all the time. But with on-off oil and gas burners, more venting is often needed to get the steam to the ends of the mains quickly so all radiators will get steam at the same time. Measure the length and diameter of each steam main and we can tell you what's needed.

If the leak around the boiler is a crack in a section rather than a rotted-out return line where it connects to the boiler, a new boiler will be needed. But if it's a pipe leak the pipe can be replaced. A-S boilers of that era were built like tanks and lasted a long time. Whether or not you replace the boiler, the job is not finished until you do a combustion analysis with a digital analyzer. This will ensure the burners are running at maximum efficiency and not producing Carbon Monoxide.

When this grand old system has had the needed repair work done, it will last at least another 80 years and provide a level of comfort and efficiency that's hard to beat.

I'm in Baltimore, so let me know if you run into any problems.


    JJJJJ Member Posts: 12
    Boiler Pressure Control and Thermostatic Radiator Trap Testing

    How do I determine what the pressure cut-in and cut-out's are for this boiler? How are the settings changed? The outside of the boiler has an Internal Syphon Compound gauge manufactured by Marsh Instrument Co. The gauge ranges from 30 vac to 30 press. It is wired to a small American Standard box (pressuretrol, I think) inside the outer jacket of the boiler. It is summer now in Pittsburgh, so the boiler has not fired recently. The gauge now reads 8.5 on the vacuum side. Also, the boiler has a slow leak, which leaves a puddle. It is possibly near where the wet return
    enters the boiler.

    I would like to test the Dunham Thermostatic Radiator Traps
    because there is occasional water hammer (banging) in places when the boiler runs. I want to use a Tempilstik to test each trap. How high should I set the thermostat to test? The temperature generally reaches the mid 80's around this time of year. What temperature of Tempilstik should I use? The only temperature ratings I can get without special ordering are 200F and 225F.

    Here is some background information about the heating system:

    The house is approximately 75 year old house with the following American Standard Gas Boiler (Series 2B-J3; Boiler G-606), installed in 1967. The house has a two pipe steam heating system. It has three types of radiators: plain pattern cast iron (U.S. Radiator Corp.), concealed radiators (McQuay Radiator Corp. probably), and two Base Ray's. Each radiator has a Thermostatic Radiator Trap (C.A Dunham Co. No. 1A) and a Dunham Packless Radiator Valve. The house also has two steam mains with a Dunham 1E trap installed near the end of each main. The dry returns connect the wet return through an Air Eliminator (Dunham Type No. 220).

    I assume it is a vapor system, since there is no vacuum pump apparent, and a gravity system, because condensate doesn't appear to return by any mechanical means.
  • Big Ed
    Big Ed Member Posts: 1,117

    JJJJJ Member Posts: 12
    American Standard G-606 Boiler and Thermostatic Radiator Traps

    In regards to the venting, here's the length and diameter of the steam mains:

    Main #1 = 70 feet, 3 1/2 inches
    Main #2 = 45 feet, 3 1/2 inches
    Main #3 = 41 feet, 2 1/2 inches

    Note: the mains are insulated with asbestos, as are the wet returns, and some other piping.

    The main reason I would like to test the thermostatic radiator traps with a Tempilstik, is so that I can test all of the traps at the same time. I ordered a 206 degree F Tempilstik. I could also order a 213 degree F Tempilstik, or other temperatures, if that would be more appropriate.

    I have a source for replacement sections and push nipples for the American Standard G-606 boiler. This boiler has an AFUE of 80. I'm inclined to keep it, since it really is well built compared to the newer ones, and the near boiler piping could remain unchanged.

    I am calculating the total load in square feet of Equivalent Direct Radiation for the house to try to determine if the boiler is really oversized. I will post questions about radiator ratings in another post.

    I still haven't determined the exact source of the boiler leak. It looks like I would have to remove the low water cutoff tapping in front of the boiler. I can't remove the back cover because the wet return pipe and wall are in the way.
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