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If you’re gonna have a fireplace….

davidmeiland | Posted in Mechanicals on

I looked at a house today that has a couple of wood-burning fireplaces. They are back to back in separate rooms. One of them has metal-framed glass doors that are tight fitting but not gasketed; the other has mesh curtains. They both have old-school metal dampers right above the firebox, the type where you can reach in, grab a short metal arm, and open or close the damper by engaging notches in the arm on a pin. They both have small make-up air inlets in the firebox sides that are run to the exterior. They both have stubs for gas log lighters. The chimney they share appears to be masonry all the way up to a metal cap and spark arrestor–I stuck my head in and looked up, and there’s no metal pipe in sight.

The general complaint in this house is air leakage, and of course the fireplaces are part of the problem. I’m going to test the house next week and I’m sure I’ll be able to pull plenty of air in thru both of them.

My specific question: what, if anything, is state of the art for a fireplace and chimney set-up like this, in terms of dampers or other means of preventing air infiltration when they’re not in use? I know that glass doors on the one would help, but would like to have other suggestions as well. This is new construction, so taking down the chimney is not in the cards!

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  1. Danny Kelly | | #1

    Not very state of the art but for $20 you can get an inflatable chimney balloon. Assuming you are not going to use them much, install the balloons and will keep the air from escaping. If you do want to use them occasionally, deflate the balloon and reinstall when finished. Installs and removes in minutes.

  2. Riversong | | #2

    There are at least a couple chimney top gasketted dampers on the market. But those chimneys need to have refractory flue tile or SS liners for wood burning.

    It may also be possible to have them reconfigured into Rumford fireplaces by a skilled mason, which is the only truly efficient fireplace.

  3. Daniel Ernst | | #3

    I'll second Robert's post.

    I've used the Lyemance chimney top damper. It's typically installed on an 8" x 12" clay flue liner (note that the sizes of these liners depends on the supplier, there is quite a bit of variation). As Robert noted, they sell a conversion kit also---for an 8' round double-wall stainless chimney pipe.

    It's spring loaded system (normally open). You run a stainless steel wire down the flue liner, install a handle and locking mechanism at a location convenient to the fireplace or woodstove.

    The damper has a silicone gasket that is compressed against the metal frame (knife edge). This compression is adjustable at the locking mechanism; you slide a set screw and bushing along the stainless steel wire to increase or decrease compression.

    On a side note, how will you handle the intake? Potentially, that's another big item. Can you install a valve on the supply pipe, somewhere close to the fireplace?

  4. 2tePuaao2B | | #4

    When you say that they have stubs for gas log lighters does that mean that they have gas lines supplying them?
    I just completed a project in MD that had 3 corner masonry fireplaces, all using 1 flue. We added stainless 3" flex liners ~ one to each FP and installed rather efficient Mendota gas FP inserts. These units draw outdoor air, are sealed at top and bottom of flue as well as at the FB face.

  5. Danny Kelly | | #5

    Robert - have you had success converting a convential firebox to a Rumford? I would have thought there would be an issue with flue location, size or something like that.

  6. Riversong | | #6


    I was part of a renovation crew that rebuilt three fireplaces and converted them into something approaching the Orton variation of the Rumford. Orton popularized Rumford fireplaces in his book The Forgotten Art of Building a Good Fireplace and added the slanted back. The real key to the Rumford, in addition to the proportions, is the gently curved throat to create a laminar air flow so that the room air acts as a smoke screen. It's possible to convert a conventional fireplace into a Rumford, though the chimney flue may have to be reduced or lined.

  7. Riversong | | #7

    Here is one of the conversions:

  8. Riversong | | #8

    Here is the second:

  9. Battic Door | | #9

    How To Reduce Your Energy Bills / Energy Conservation Begins at Home

    Imagine leaving a window open all winter long -- the heat loss, cold drafts and wasted energy! If your home has a folding attic stair, a whole house fan or AC Return, a fireplace or a clothes dryer, that may be just what is occurring in your home every day.

    These often overlooked sources of energy loss and air leakage can cause heat and AC to pour out and the outside air to rush in -- costing you higher energy bills.

    But what can you do about the four largest “holes” in your home -- the folding attic stair, the whole house fan or AC return, the fireplace, and the clothes dryer?

    To learn more visit

    Mark D. Tyrol is a Professional Engineer specializing in cause and origin of construction defects. He developed several residential energy conservation products including an attic stair cover and an attic access door. Battic Door is the US distributor of the fireplace plug.

  10. Danny Kelly | | #10

    Thanks Robert - impressive. Didn't think that was possible.

  11. Riversong | | #11

    Battic Door,

    If you want to place an ad here you should pay for one.

    I ordered one of your EZ hatches, which was not sized as advertised and would not fit between standard 24" oc framing. I was not impressed with the quality or the value for price. I would not buy from you again.

  12. 2tePuaao2B | | #12

    Nice looking work Robert. How old is that property?
    Did you use a plywood template on edge as a guide for the back curve or did you put "the good eye" to it?

  13. Riversong | | #13


    I didn't do the masonry work - we had an expert take care of the fireplace restoration.

    I don't know the vintage of the building, but it was the only historic restoration project I had the pleasure to be part of. It was on the common in Walpole NH and at one time was a dentist's office. We did the work in 2003 and it was a $400,000+ renovation for a new Boston owner.

    Interior walls and ceilings were replaced with blueboard and plaster - brown coat on the walls for texture and hardcoat on the ceilings. All interior moldings were reproduced in poplar with custom-made shaper knives, and I fabricated and installed all of the built-in cabinetry as well as those cedar window planter boxes that the owner insisted on reproducing.

  14. Frank Casini CT. | | #14

    Re; Orton's book and the slant version of Rumfords
    I am a 3rd generation mason who has building rumford fireboxes with slanted backs.I first started building them when a customer handed me a Vrest Orton book on fireplaces around 1972 and have had great success.
    There are those whom frown on the slant as they believe Count Rumford advocated only the straight back. Though he built just one slant version which was almost at the end of his fireplace repair career,he wrote how it amazed him as the best heater of all repairs he ever did.
    He noted how he was going to set up experimentation and reveal his findings he never did which is what some use as a rejection stamp for the slant version, rather I attribute the non interest and silence on the emergence of the Franklin Stove.
    Those who insist on the straight back due to their claim that their throat is shorter thus uses less house air for draft but I have proven the longer throat can be cut down to a constant 2-3/4" via a adjustable damper,where as the straight back has to stay fixed or risk smoke.
    I have photos and a video I took this Christmas showing my home's FP burning at this 2 3/4 setting and anyone interested can leave comments .!/pages/Casini-Masonry/159609824086030

  15. user-1067183 | | #15

    Well seems like a good top damper is key here.
    I haven't seen any mention of chimney liner though? Seems to be a good idea in masonry chimneys -,

    So, how did things turn out?

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