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  1. #1
    Join Date
    Jan 2018
    Location
    Danbury, CT
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    fireplace make-up air

    I have read a few articles on this subject already but cannot find an answer that will solve my problem. I have a center chimney colonial that was totaly rebuilt. Spray foam, new windows doors... It is a very tight house. The chimney was rebuilt with modifed rumsford fireplaces. I have two fireplaces on the first floor and two on the second floor. The large fireplace in the kitchen is 5' wide, 42" tall. When I start a fire in the kitchen fireplace smoke pours in the second floor bedroom chimney and fills the room. I have top seal dampers on all flues but the smoke is getting in anyway. If I open a window in the bedroom the smokes appears to slow down or stop. All appliances are off, exhaust fans, dryers... The only thing running is the forced hot air system. How can I supply make-up air while the fireplaces are running? I have seen the make-up air kits for the exhaust fans but what about for the air loss up the chimney when the fire is on? They installed small air vents in each fireplace but I do not think they are working. I do not feel air flow out of them. Does a system exist that can sense the pressure differential between inside/outside and turn on to compensate automatically? How can I resolve this issue so I can use the fireplaces without dying?

  2. #2
    Join Date
    Aug 2004
    Location
    S.E. Pa
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    7,262
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    Whomever steered you towards open hearth fireplaces in a very tight home did you no favor. First of all, the home must meet the ASHRAE 62.2 minimum ventilation std. of 0.35 Air Changes per Hour (ACH). Next, you probably will need additional MakeUp Air (MUA) especially for that massive kitchen fireplace. It alone probably exhausts about 1,200 CFM. Where's that coming from? Forced air heating that has imbalanced ducts can easily over power any open hearth fireplace. Have a certified technician actually measure and balance your ducts so they do not create pressure regimes that result in negative pressure zones.

    As for MUA systems in residential applications, there isn't much out there. The trigger pressures are so tiny: negative 3-5 Pascals, there aren't many systems that can sense that low. Worse, since this pressure gradient fluxes constantly, you would need a switch that averages over a reasonable time so the MUA system isn't switching on and off every second. There are passive MUA systems that rely on negative pressure to feed itself. These are wholly unreliable as proven by a study conducted by ASHRAE that showed passive MUA systems don't work reliably. The powered systems are better suited for applications such as energizing when a furnace or boiler control calls for heat to supply MUA for that one appliance in a confined space mechanical room.

    Rumford (loose the 'S') fireplaces do perform better than modern fireplace designs but are not bullet proof as you've found out. My question is about the chimney: were they built from scratch or relined and are the flues listed stainless steel or traditional terra cotta tile lined? Regardless you need a Level II inspection with a video camera to ensure the integrity and suitability of those chimneys. This would also include checking the measurements of the flues to the fireplace opening.

    There are only two F.I.R.E certified inspectors in CT: in Windsor and Middletown. There are about 45 CSIA certified sweeps in CT. Look for one who's taken the Chimney Physics course.

    HTH

  3. #3
    Join Date
    Jan 2018
    Location
    Danbury, CT
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    5
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    Thread Starter
    The chimney was a tear down and rebuilt with terra cotta flues. The chimney about 5 years old. The mason was not the sharpest tool in the shed. It was very expensive to put in. The large fireplace has two (2) flues. The upstairs fireplace with the smoke issues flue is right next to the two flues from the large fireplace. I would love to use the fireplaces and cannot afford an expensive rework. Has anyone worked with a reliable certified chimney sweep in the Danbury CT area?

  4. #4
    Join Date
    Aug 2004
    Location
    S.E. Pa
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    Regardless get a Level II inspection with video camera. Make sure they consider the presence of a 4" wythe between flues and calculate the flue sizing.

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