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shelf-spare for millivolt gas valve?

Binnacle
Binnacle Member Posts: 126
edited November 2014 in Gas Heating
Have a superlative 50+ year old gas-powered steam
boiler driving a 90 year-old radiator system, all with
essentially one moving part:

Honeywell thermopile gas valve "Powerpile" VS8187A 1003 2

The system is amazing and the thought of changing the
ingenious control to a "modern" 24v setup makes my
head rotate 360 degrees. I'd rather pay the extra $7
a month to to run the pilot in the winter knowing I will have
heat again the next time a hurricane takes out the
electric for 10 days.

I'm thinking I should stockpile a spare valve (or two) in case
this one fails. Hate to be cold, and it appears millivolt
systems are fading away and parts for them are becoming
increasingly hard to obtain. In addition, replacing the
badly adjusted Pressuretrol with a finely tuned Vaporstat
has resulted in the gas valve cycling up to six times per
heat cycle, compared with once per cycle in the past.
So the old valve is experiencing a elevated degree of
wear-and-tear.

New and used VS8187A valves can be purchased
on eBay, and an outfit, Keith Specialty, is selling
new VS820A valves indicating they are the current
model substitute.

Please anyone with experience and an opinion
on the subject chime in with thoughts, comments
suggestions. I'm quite interested in knowing
how likely these gas valves are to fail.

I have already decided to stockpile two thermopiles
since these definitely do go. The existing one
reads 0.50 volts instead of 0.75 volts so it could
already be near done, though I have not yet
checked the voltage with the thermostat wire
disconnected and can't be 100% sure the voltage
loss is not a result of wire resistance.

Also see a gas-pressure regulator. Replacing
that seems less of a worry if it fails. Any thoughts?

Comments

  • why has the cycle timing changed? Could it be short-cycling for other reasons? Even these old millivolt valves would prefer fewer cycles!
    certainly having a boiler which will keep going during power outages is a real plus.--nbc
  • Binnacle
    Binnacle Member Posts: 126
    edited November 2014
    burner/gas-valve cycle ≠ system cycle

    The system is not short cycling.

    Per my comment, the pressuretrol was
    badly adjusted. Prior to my owning the
    house the system would run up over 4psi
    with half the pipes banging, one radiator
    gurgling and wailing though possessed by
    a demon, and the temperature swinging
    ten degrees. One big bad burn that was
    easy on the gas valve and murder on
    the rest.

    Vaporstat (among other improvements)
    keeps it between 5 and 8oz and it runs
    like a dream. But this requires the burners
    to turn off and on and therefore the gas
    valve must close and open. The valve
    is a mechanical device subject to wear
    --more now than before. Possibly the valve
    is as old as the boiler which was manufactured
    in 1961 and presumably installed soon after.

    Perhaps the boiler is ovresized (have not
    yet calculated radiator surface area), but
    this is moot as there's no chance I would
    replace a slightly oversized but otherwise
    perfectly excellent boiler just because the
    gas valve might wear out.
  • Tim McElwain
    Tim McElwain Member Posts: 4,506
    Have a superlative 50+ year old gas-powered steam
    boiler driving a 90 year-old radiator system, all with
    essentially one moving part:

    Honeywell thermopile gas valve "Powerpile" VS8187A 1003 2
    NOW OBSOLETE IF YOU CAN STILL GET ONE ON EBAY GRAB IT UP. IF NOT THE VS820 IS A GOOD REPLACEMENT JUST WILL REQUIRE REMOVING THE GAS REGUALTOR THAT IS AHEAD OF THE VS8187 (THE VS820 HAS A BUILT IN REGULATOR IN THE VALVE)

    The system is amazing and the thought of changing the
    ingenious control to a "modern" 24v setup makes my
    head rotate 360 degrees. I'd rather pay the extra $7
    a month to to run the pilot in the winter knowing I will have
    heat again the next time a hurricane takes out the
    electric for 10 days. NEVER GET RID OF THE POWERPILE AS IT MEANS YOU WILL ALWAYS HAVE HEAT IN A POWER FAILURE AND NEW 24 VOLT SYSTEMS ARE NOTHING BUT TROUBLE COMPARED TO POWERPILE.

    I'm thinking I should stockpile a spare valve (or two) in case
    this one fails. Hate to be cold, and it appears millivolt
    systems are fading away and parts for them are becoming
    increasingly hard to obtain. In addition, replacing the
    badly adjusted Pressuretrol with a finely tuned Vaporstat
    has resulted in the gas valve cycling up to six times per
    heat cycle, compared with once per cycle in the past.
    So the old valve is experiencing a elevated degree of
    wear-and-tear.

    New and used VS8187A valves can be purchased
    on eBay, and an outfit, Keith Specialty, is selling
    new VS820A valves indicating they are the current
    model substitute.

    Please anyone with experience and an opinion
    on the subject chime in with thoughts, comments
    suggestions. I'm quite interested in knowing
    how likely these gas valves are to fail. IF IT AIN'T BROKE DON'T FIX IT.

    I have already decided to stockpile two thermopiles
    since these definitely do go. The existing one
    reads 0.50 volts instead of 0.75 volts so it could
    already be near done, though I have not yet
    checked the voltage with the thermostat wire
    disconnected and can't be 100% sure the voltage
    loss is not a result of wire resistance.
    PROCEDURE FOR TROUBLESHOOTING WHICH I DEVELOPED IS AVAIALBLE HERE ON THE WALL. JUST GO TO THE MAIN PAGE AND LOOK AT THE TOP FOR HEATING MUSEUM THEN TIM MCELWAIN AND FIND "PROCDURES FOR TROUBLESHOOTING POWERPILE SYSTEMS"

    Also see a gas-pressure regulator. Replacing
    that seems less of a worry if it fails. Any thoughts?


    Post edited by Binnacle on 1:10PM

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  • Tim McElwain
    Tim McElwain Member Posts: 4,506
    YOU CAN ALSO CLICK BEFORE YOU ASK AT THE TOP OF THIS THREAD AND FIND THE SAME THING.
  • Binnacle
    Binnacle Member Posts: 126
    edited November 2014
    Tim, thank you for your reply!

    >Never get rid of the Powerpile as it means
    >you will always have heat in a power failure
    >and new 24 volt systems are nothing but
    >trouble compared to Powerpile.

    Never crossed my mind!
    Perhaps I should have been more
    literal rather than referencing a
    scene from "The Exorcist" (film, 1973)

    I learned about millivolt after the
    fabulous surprise of heat during the days
    after Sandy. Had just purchased the
    house and most new-old house
    surprises are, of course, not so pleasant.

    The millivolt control is a thing of beauty
    --elegant and simple. I suspected
    24V is less reliable and you confirm this.

    So I will go hunting for a VS8187A spare
    --one inch pipe as I have learned they come
    in a few sizes. Good to know the VS820A
    will do in a pinch and that the regulator
    should be removed if an 820 goes in.
    If I can't find a VS8187A fairly soon
    I'll purchase a VS820A as the spare
    part.

    >I'm quite interested in knowing
    >how likely these gas valves are to fail.
    >
    >IF IT AIN'T BROKE DON'T FIX IT.

    Not planning to touch the existing
    valve--I want to be prepared if it
    ever does fail. Does this happen eventually?
    Seems this unit may be 50 years old
    (incredible), but nothing lasts forever.

    >Procedure for troubleshooting which I
    >developed is available here on the wall. . .

    Super. I'll read up on it and see if the
    existing thermopile needs replacing
    due to the voltage drop. Thank you!
  • Binnacle
    Binnacle Member Posts: 126
    wow, just snagged a spare one-inch VS8187A on eBay from a reputable seller; feels like good luck as 1" units are not showing in completed listings (though 3/4" is common)

    Now nothing related to heating can ruin my winter!

    (boiler water has been 300ppm OH alkaline since last year and the iron pot no longer rusts)