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Winterizing a 2 Pipe Steam System

JUGHNE Member Posts: 11,111
This is a 1933 school house building. That district has joined with other towns and now have a new school.
1933 owners want to hold on to the building 1 more year as they think they may have a buyer.
But they would like to not heat it and inquired about winterizing.

It is a 2 pipe attic express that down feeds2 floors. 5" + 6" mains in the attic. I have never seen them and do not wish to.

I am thinking all water should drain back (in theory) to the boiler:
except F&T's which are fairly new with drain valves/plugs that could be opened.
Cond pump that would have to be drained.
LWCO's are an easy drain
90% of the rad traps have been emptied of elements as orifices installed in supply valves.
There are about 25-30 drip legs/dirt pockets that would hold water.
The testable back flow device would have to be drained/removed as would the water meter.
There is no fire sprinkler system in the building.

However, there are under floor true dry returns....the boiler is a half level down from grade. These were replaced by someone else and I don't thing they were pitched to drain towards the boiler room.
Evidence being that the system was slow to vent air. Adding BJBM's to the EOM drips improved the steam delivery tremendously.

I am reluctant to shut down the steam system because of the possible water left in the "dry" returns.

Also insuring that the domestic water is totally drained is questionable also.

I am suggesting to leave the steamer on and shut down and drain the domestic as possible. If a break on domestic at least no flooding.

Any other ideas?


    EBEBRATT-Ed Member Posts: 15,849
    I agree with you.

    I would leave the boiler on at say 55 degrees.

    If I was the owner I would look at what the building is worth now versus what it would be worth if they had a freeze up.

    I think burning some fuel is the smart choice plus possible damage from condensation etc.

    I doubt the insurance company would like the idea of a unheated unoccupied building. + the money it will cost to winterize and unwinterize.

    In any event weather winterized or not the building should be checked maybe even daily when the temps are low.

    With the temp set at 55 your probably talking mid November to mid March
  • mattmia2
    mattmia2 Member Posts: 9,981
    Even if you do successfully winterize it (and you almost certainly will miss something somewhere that will freeze and be damaged), the cold temps will damage that plaster and other interior finishes.
  • Jamie Hall
    Jamie Hall Member Posts: 23,675
    All of the above...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 11,111
    Thanks to all of you. That is the response I expected.

    I will suggest leaving steam on 55-60.
    Perhaps disconnect domestic to prevent flooding.
    May have to run a temp CW line just for the boiler.

    Another old building I will miss. Unique steam supply system.
    I have the original prints, they show the radiation EDR down to the fractions.
    The 1933 print shows a 5" X 3 1/2" X 3 1/2" eccentric tee in the attic. I have wondered if it really exists or is built up with nipples and reducers. I guess I will never see it.

    First building burned out in 32, they rebuilt in 33, using remains of footings etc.
    This is the original boiler room. Surprisingly the fire did not start in the coal burning boiler room.
    Today has NG 1973 American Standard 1BJ2--G-10-10/1440
    1.8 MBTUH input, 4563 EDR.
    Sized right for the 1973 building, but now oversized.
    One burner on each end is capped for down firing.
    7 of the 9 are now firing.....17/64" gas orifice spuds.
    Operating pressure is 1.7 to 2.75 PSI with minor short cycling.
    Original design was 106 BTU per sq foot. Plenty of fresh air.
  • dopey27177
    dopey27177 Member Posts: 887
    Leaving an useful building that is temporarily abandoned is a recipe for disaster.
    There are two many things that can happen with pipes,that have some water left behind. two properly protect the domestic water system drinking alcohol and flushing when putting it back in service. filling te boiler and return lines with glycol to prevent freezing an item that steam boilers do not like and willcause problems when put back into service,

    My approach is to operate the system at 50 to 55 degrees to prevent freeze ups.