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Vent damper disabled?

Alex265Alex265 Member Posts: 41
I noticed that the FieldControls GVD-6 vent damper, installed on my gas boiler, was in the 'hold open' mode set by the switch on the damper. I switched it to 'automatic' mode, and it seems to be functioning properly. However, I am wondering, can there be a reason why this control would be disabled on purpose, so that I should not enable it?


  • haaljohaaljo Member Posts: 112
    just a homeowner

    with 1939 National steam boiler with standing pilot gas conversion burner.  I recollect many years ago being told I could not install an automatic vent damper here in Massachusetts. I would like to have that done and maybe the rules have changed? Might be relavant to your question.
  • Alex265Alex265 Member Posts: 41
    This is interesting

    Thanks for the reply. The vent damper has been initially installed with the boiler, and the inspection guy didn't say anything about it. But may be he didn't say anything _because_ the damper was in the 'hold open' mode?

    Not considering legal aspect - is it better to have the functioning automatic damper? Or it depends? Or are there opposite opinions as with almost everything else? Is it possible that damper shuts in some kind of condensation in the boiler?
  • Tim McElwainTim McElwain Member Posts: 3,893
    Someone may have

    inadvertently left it in the wrong position. If it is working now then it is fine. Automatic vent dampers come on many standing pilot 24 volt design gas boilers so they are okay for all states for installation that I know of.
  • Tim is correct,,

    but I would make sure the louver-plug has been removed if it is standing pilot. ;-)
  • Alex265Alex265 Member Posts: 41
    Thank you for your advice

    It is intermittent pilot.
  • icesailoricesailor Member Posts: 7,265
    Disabled Vent Dampers:


    I don't know the answer to this and I don't do Nat. Gas.

    He said that he has an "intermitent pilot". Is it still OK?

    Must the burner be wired so that the burner can not come on if the damper is in the closed position? Should the unit be checked for proper operation? IE: that the damper opens before the burner comes on, and that it closes after the burner stops and whatever?. Perhaps there was a problem with the operation of the damper assembly and someone moved it into the full open at all times mode rather than fixing it or removing it.

    I'm just asking.
  • Alex265Alex265 Member Posts: 41
    icesailor, thank you for your concern

    and I am thinking along those lines too - was the switch left in this position inadvertently or may be there was a reason.

    The control seems to be functioning properly - it opens when thermostat calls for heat, and only after it's fully opened the burner comes on. After thermostat breaks the call and burner stops, the damper closes. Both operations take no more than 15 seconds. I checked all this several times. I would hope that if the control was broken and left in the open position on purpose, then whoever did that would had left a note.

    Is another possibility - the damper does not really help with operations efficiency on this boiler and though it was installed by code, it was left open in order to never cause any problems?
  • Tim McElwainTim McElwain Member Posts: 3,893
    A lot of techs

    do not like vent dampers so they make them inoperative as a matter of practice.

    The damper was part of the design on this equipment and will have redundant end switch contacts both of which have to close before the system will spark and light the pilot and then bring the main burner on.

    From the gent posting it sounds like that is what is happening. The vent damper typically adds about 3 to 5% savings to the operation of the system.
  • AFUE ratings,

    to your unit ONLY apply to your boiler IF the supplied equipment is installed & operating properly.

    So, take whatever course you want. 
  • JosephJoseph Member Posts: 139
    Does your chimney have a stainless steel liner?

    If you have an external clay liner chimney (most older homes have clay liner chimney), the closing vent damper can make the chimney condensate and eventually crumble creating a hazardous condition. If you have a stainless steel liner, then your protected. Could be someone left open damper because you don't have a liner and they felt its safer for you in the hold open position.  
  • Or maybe,,,,

    someone just "muffed-up",,, this thread is getting crazy! 
  • Alex265Alex265 Member Posts: 41
    In fact,

    this is exactly the case, the chimney didn't have steel liner until recently.
  • haaljohaaljo Member Posts: 112
    and my old steamer'schimney does not have a metal liner

    and that is possibly why I was told an automatic damper was no go. Wow, that was over 30 years ago. I remember Comm Gas (Boston area) replacing the rented conversion burner and the Tech telling me I couldn't install a damper.

    If it increases efficiency only 3-5 percent then not a big deal. Writing this, I recollect there were a lot of problems with these dampers back then. Also, remember gizmo's capturing stack "waste" heat and that they were a bad idea.

  • SteamheadSteamhead Member Posts: 11,323
    What kind of conversion burner

    do you have? What model National boiler is it? 
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • Tim McElwainTim McElwain Member Posts: 3,893
    Vent dampers are not

    allowed on conversion burners so that would have been why Comm Gas would not install one.

    Vent dampers are used on most equipment today to get the system above the DOE energy efficiency standard.

    It was not unusual in the past for conversion burners to be installed on systems with unlined chimneys as there was no requirement to line them back then.

    The other things referred to were heat reclaimers which were a real problem as they caused sooting.
  • haaljohaaljo Member Posts: 112
    "National Radiator Corporation

    Heating Boiler - Size 018-6 - Serial 100N711"

    with Economite E20 Burner

    Art Deco Style and Turquoise Color
  • Tim McElwainTim McElwain Member Posts: 3,893
    +Ha Ha now we have it

    the E-20 power conversion burner is not supposed to be used with a vent damper. Someone set it to stay open all the time rather than remove it is my guess.

    Your choice if you want to have it removed would be my answer.
  • haaljohaaljo Member Posts: 112
    Tim, that's crash2009 that has the damper disabled

    and he's got a new system with chimney liner just recently installed.. I was looking to find out why I couldn't put a damper on my E20 on my national radiator company steamer. So far, I got no liner and the E20 is not vent damper allowed. But if it's only 3-5 percent; it's no big deal with the way gas prices are (for now). Seems like it would be a lot more for my old-tme boiler?

  • SteamheadSteamhead Member Posts: 11,323
    With a power burner

    the off-cycle loss without a damper is much less than with an atmospheric, since the air inlet openings are rather small.

    If that's a 3-pass boiler with big flue passages, you might consider having a pro add baffles so the hot flue gases will wipe the cast-iron better. Don't try this yourself, you must verify that the draft over the fire is not impaired. This requires combustion-testing equipment and know-how.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • DannoDanno Member Posts: 1
    Vent Damper on manual overide?

    Mother in law has a 2 yr. old peerless with a effikal vent damper.  it is installed just below the air intake of the flu pipe....we had a couple of problems and a tech told me it would be $1300 to replace vent damper and pipe.  Called another company who told me to leave it in manual overide for ever and it will be fine, just a little more gas will be burnt (5% efficiency)  He said they don't replace them in his shop because they continually break down and are completely unnecessary.  The have been doing this since they came out.  He checked to see if mine was recalled and said it wasnt but he also said he had done this to well over 500 units with no problems.  Is this safe?  Is he right?  He told me if I really wanted it replaced to order the same exact one (he gave me a supply house) and said he would come back for $25 and it would take him less than 2 minutes to unplug the od one and put the new one in...or i could follow the directions and do it myself in 2 and a half minutes.  What do you think?
  • icesailoricesailor Member Posts: 7,265
    Vent Damper/UL Listing:

    I think that there is a UL listing on this application/appliance. The listing includes the vent damper. To disable the vent damper makes it not conform to the listing. If something happens, and it doesn't need to be caused by the lack of vent damper, your insurance company could deny a claim made by you for modifying equipment. It may be BS but it can happen. And the person who gave you that advice is a fool to tell you that.

    That's my opinion.
  • SteamheadSteamhead Member Posts: 11,323
    edited January 2011
    Replacement motors are available for these dampers

    Effikal is now owned by Field, which markets these replacements. If the damper itself is in good shape, it's a lot less labor-intensive to just replace the motor. I think the motor part number is GVD-RMA or something like that.

    Since many of these atmospheric  boilers are hooked up to old chimneys that could develop enough draft to operate a coal boiler, the damper is essential for keeping the boiler from cooling down between firing cycles.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • Mark EathertonMark Eatherton Member Posts: 5,582

    I think I disagree with your statement. Unless the damper bypass switch was installed AFTER the fact, it is not considered a "modification", and the approval agency was aware of the fact that it was incorporated into the logic of the device. Having it turned to the bypass position will not void any warranties or insurance company requirements. It just wastes energy. (maybe 5%)

    What REALLY concerns me, is that the O.P. posted that it is installed BEFORE the draft relief/diverter. Now THAT would cause a raise in my eyebrows...

    The biggest problem I have experienced with the dampers is that either the motor misses the call to open (dead spot on the armature?) or it opens and the end switch doesn't make. If that happens, the switch gets thrown. I have replaced many of these dampers, only to have them fail again in either mode.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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