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Two-pipe steam system from 1928 - Return gradually becoming 'slow'

I have a steam system original to a 1928 house in Massachusetts. It is a Warren Webster (of Camden, NJ) "Type R System" It is a "two pipe" system (supply and return).
The Warren Webster "Instructions" say:
RADIATOR RETURN TRAPS (Webster Diaphragm No. 7 Traps) provided at the discharge end of each radiator. They are entirely automatic, discharging air and water of condensation silently, but keeping steam in the radiator until its heat is entirely used. They will normally require no attention. (About which I understand, and have been replacing them - have more to replace - further discussion below)
VENT TRAP Water and air that pass through the Radiator Return Traps enter the Webster Vent Trap, which discharges the air into the basement through the vent valve and prevents overflow of water. The Vent Trap is automatic. ( I hear it working - it has a bit of a characteristic 'whistle' when it releases air. "Prevents overflow ..." It has a float ball on an arm in it. I am thinking that when the float rises, it closes a valve leading to the rest of the return system below. As noted below, I don't think the whole return system is working fully effectively. Does the arm of these things get "sticky' after a hundred years?
VENT VALVE ...contains a light-weight hollow ball. To clean, unscrew cap, take out ball, clean any dirt from ball and seat and replace. Care should be taken not to drop this light-weight hollow ball on the basement floor... (Yuh, that things weighs about half as much as a ping-pong ball of equivalent size -- I can't imagine where I would ever get a replacement - that said, configuration considered, the pressure that lifts that thing has to be very little. AND the 'pipes and convectors' side of the system (i.e. the upstairs) often goes into a vacuum as the boilers turns off and steam condenses. There are 'swing' check valves below, but I am not persuaded that the TRAP / VENT VALVE release as much air as soon as the two should.)
BOILER RETURN TRAP is provided to assure positive return of water to the boiler regardless of boiler pressure. It [too] requires no attention, being wholly automatic. Under very low pressures, water returns by gravity direct to the boiler and the Boiler Return Trap will not be in operation. At higher pressures, it will operate as often as required. (.... which is an "explanation" that does very little explaining. Dear Mr. Warren and Mrs. Webster: where does the pressure go, to push what, to make the Boiler Return Trap "operate"? I wish I knew.)

The particular boiler is a 300 or 350,000 BTU gas steam boiler, installed in about 1970-1975. (It hasn't cracked yet) I am the person who opens the blowdown valve (briefly) every ten days or so, empties the boiler and refills it with treated water once a year, changes steam traps, etc.

And, after that excessively long recitation, I try to describe my problem:

It seems to me that the boiler now, too readily, steams itself to relatively low water - that stays too low too long. There is a low water cut-off that is not always tripped, but is tripped now more often than in my years not really understanding this system, but appreciating having it keep me warm.. The boiler has a low pressure switch that turns off at about 1 psi to maybe 1.25 - something like that (there is no problem with steam getting to the upper floors). Part of the return system / path is a fairly long (40 feet) "wet" section that runs only about 8" above the basement floor, and is "wet" in the sense that it is below the in-the-boiler water line (goes up to re-join the other return, run through vent trap and boiler return trap.

My questions, some of them stupid (sorry) - and in no particular order;

- Do radiator steam traps of the Warren Webster "diaphragm" kind (heat expands diaphragm - closes outlet / cooling re-opens outlet) become partial or intermittent? Sometimes just by taking temp of input / output just after startup, one can say the trap isn't closing - that's easy. It is harder to figure out when they are cooled that they aren't not really opening enough to let the water get back to the boiler (without taking pipes apart,etc...)

- What are the chances that the long, low wet loop is by now in fact a long, low 'blockage' more than it is a pipe, that some elbow is just a "rust corner"? I have had thoughts of opening it up in the middle somewhere and putting a small pressure hose (think pressure washer) down it. Reasonable? Dumb?

- After only a hundred years, do those "automatic" Warren Webster bits of apparatus that "need no attention" get to be rebuilt or replaced? If so, are there cleverer pieces of gadgetry with which one can replace them?

- Since the boiler itself is almost half a century old, should I be thinking about turning the whole house into some kind of hot water system anyway?

Many thanks to all who (show pity) and answer.


  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    With regard to last question -- NO! Don't even think about it! What you have is one of the best steam systems made, and any change will be for the worse.

    Now. Having said that, do you have a copy of "The Lost Art of Steam Heating", available on this site from the store or, I think, from Amazon? If not, get one as soon as you can. The entire Warren-Webster system is described in vast and terrible detail, and you should read it.

    In general, steam traps do not fail if they haven't been abused. Overpressure abuses them... It can be a little hard to determine whether they are working, but as a general rule if they fail closed, the radiator won't heat at all or very poorly indeed -- and if they fail open, the return pipe will be steam hot -- not just very warm or hot -- and other radiators nearby may not heat well. It would be beyond rare for a trap to fail partly open, or only sometimes.

    Wet returns, on the other hand, do clog, and if you can figure out a way to flush yours out it will probably help matters. I don't suppose there are any handy unions?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Pumpguy
    Pumpguy Member Posts: 654
    See if you can locate a copy of the book STEAM HEATING, A Manual of Practical Data compiled by THE GENERAL ENGINEERING COMMITTEE of WARREN WEBSTER & COMPANY,copyright 1922.

    I stumbled across my copy at a flea market some years back. Later in surfing the net I found that this whole book is available for viewing online. I thought I had bookmarked the source, but can't seem to find it now. Hopefully a good search engine will help you find it. Almost 400 pages of interesting and useful information.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • BobC
    BobC Member Posts: 5,477
    This is a pdf of that book.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Pumpguy
    Pumpguy Member Posts: 654
    BobC said:

    This is a pdf of that book.


    Thanks @BobC. I hope others will find it as interesting as I have.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • dopey27177
    dopey27177 Member Posts: 887
    Replace the two check valves at the bottom of the returns.
    When they leak the water is pushed out of the boiler into the return piping.