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Is it right to equip boiler room chimney with Electrical forced blower for omitting combustion produ

Dear Friends ,

I hope that you all are fine and doing well , as always. Also, i wish that this new year is repleted with joy, happiness, health , blessing and success in life and career for you all .

I have recently visited a boiler room whose combustion noise level is so annoying and problematic for the building inhabitants .The manager was told by the building caretaker that the burner's combustion products cause respiration problem and then the fixed up a roofed Exhaust fan to suck all the products out the boiler . Very soon after the installation , inhabitants have stated of abnormality of this decision in which they could not sleep due to combustion noise effects .

Some one introduced me to the building manager to solve the problem ;so, I have decided to share this scenario with you for your insights into this situation better . How shall we decrease combustion noise level of the sectional floor standing boiler ?

I have attached some photographs of the project to picture the situation clearly ,

Thank you in advance for your permanent support and help,

i look forward to hearing your responses,




  • Jamie HallJamie Hall Member Posts: 12,863
    Oh dear. Well, there are fan kits which can be used to convert some boilers to induced draught -- where there is a fan on the exhaust to pull the combustion products out of the system. This is really what you want. They are made in this country by Field Controls (try this link: but I'm not sure whether they would be available to you.

    Where does the boiler exhaust go now? A chimney? Exhaust stack?

    Exhausting air from the boiler room to exhaust the combustion products with it is not a safe choice. But perhaps it wasn't clear -- is that blower which you pictured exhausting air from the boiler room, or is it connected directly to the boiler's exhaust (I hope not -- that flex coupling isn't made for high heat!).

    And how does fresh air get into the boiler room?
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Tim McElwainTim McElwain Member Posts: 4,365
    It sounds like they should be bring air in not exhausting it out of the combustion zone.
  • RoohollahRoohollah Member Posts: 114
    Dear Jamie,

    Thank you for your complete response . I highly appreciated .

    As regards your questions , I would like to say that the mentioned exhaust fan is taking combustion products out of the Boiler's chimney ; in other words, the blower is directly connected to the boiler's exhaust on the roof . The fresh air for the burner comes from a window which is separated from the boiler room door .

    I have tried to browse the stated link for more information , but I am not sure they will be available on our market .

    Thank you again for your helpful feedback and time ,

    Best Regards,

  • JUGHNEJUGHNE Member Posts: 6,924
    Has anyone considered raising the height of the existing chimney?
    I see there is another building near this one, that most likely is reducing the draft on the chimney.
    Here our rule of thumb is that a chimney should be 2 feet above anything within a 10' radius.
    Is looks like you have a power burner there and that should induce enough gravity flow, IMO.
  • ZmanZman Member Posts: 5,831
    It sure looks like this "solution" is in fact the problem. Do you know exactly why the fan was added on the roof? Is it possible that there were leaks in the vent or boiler that made them think that the fan was a good solution?

    It might help to post the capacity of the boiler as well as the size and height of the vent.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • RoohollahRoohollah Member Posts: 114
    Thank you friends for your time and posts .

    As regards boiler's capacity , I would say that it has capacity of 1470000 btu/hr and the height of the vent is 78 ft . The chimney is rectangular type 30 * 20 centimeter .

    As I asked the manager , They said that " there is combustion products in boiler room" and then they come up with the idea of equipping the boiler with the blower .

    I surprised that they never go for adjusting the burner or matching size of the burner with the boiler and other technical scenarios .

    once more , thanks for your support and guidance


  • mattmia2mattmia2 Member Posts: 1,318
    Is the entire vent all the way up to the roof just a rectangular sheet metal box? In addition to needing to be high enough above the roof to draft properly, if it is just single wall sheet metal it needs to be 6" away from anything combustible which it doesn't look like it is.
  • ZmanZman Member Posts: 5,831
    The vent size sounds close. Can you find the manufactures instructions? Is there a damper of any kind in the boiler room or is it piped straight out.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ZmanZman Member Posts: 5,831
    It looks like you could quickly disconnect the fan on the roof. What does your analyzer read with it installed and without?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • RoohollahRoohollah Member Posts: 114
    Thanks for the posts . I do appreciate such support and friendship.

    As regard to the questions , I must say that there is a damper in the metallic chimney from the rear side of boiler to the main cemental rectangular chimney . I have had two heated discussions with the manager of the building and other inhabitants . Mostly they doubt the offer I handed them in . According to the size of boiler capacity and its manufacturer to fire inside of the boiler only 70 percent of its length , first I must adjust the burner properly after disconnecting of the roof blower and inspecting the inside of the main chimney for any external blocks . Also, sealing the metallic chimney for leakage of flue gas except the damper . Surely, I have learned the mentioned steps after I read the posts . That is why Heating Help is like a global university and newbies like me should educate and sharpen their skills in here .

    Yes, the first thing to do is to disconnect the blower , but about the analyzing of the combustion products , I would say that the device is really expensive here and mostly we do the job according to the color of the combustion and its products smelling .

    Once again , thank you for taking the time to assist me for proper job .


  • icy78icy78 Member Posts: 351
    Can you post a picture of the flue coming off the boiler, to the chimney?
    Is the entire flue intact? (No holes, splits)
    How is combustion air introduced?
    Is it powered into the space? Or just a hole to the outside?
    Do you have a manometer of any kind?
    Is the flue clean?

    I agree, you cant do much with that fan on the roof.
  • mattmia2mattmia2 Member Posts: 1,318
    It would be great if you find a copy of the US fuel gas code and read and follow what it says about fuel burning appliance vents
  • RoohollahRoohollah Member Posts: 114
    Excellent posts . Thank you all for support.

    I have not taken picture from the rear side of the boiler in which clearly would show the connection of the chimney , but as you may see on the picture that I post above , the vertical side of chimney is broken and they covered with piece of metallic sheet which is not sealed .

    The combustion air introduce by the forced burner into the boiler and the air of boiler room comes from the register which next to the stairs .

    No , the previous technician did not install any kind of manometer . mostly the boiler room is operating at the high cost . As I explained the problems to the manager , they get confused .
    I have just inspected the project recently and The fan on the roof is the manager idea . i have two long meeting with them and I explained the posts of my friends to them for arriving at the proper decision . But always budget lead us to the situation not the importance of technical points.

    Once again , I do thank you all for giving me some lessons for better work . Your help is greatly appreciated.


  • mattmia2mattmia2 Member Posts: 1,318
    Might remind them that someone from the government usually suddenly cares when a whole building of people are killed by poisoning, which your current installation has a high likelihood of doing.
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