build masonry FP?

[count rumsford]

Is it possible to build a masonry FP with the chimney already built in place? I have a factory built metal "heat-a-lator" type currently, but it is very rusted-through in the smoke chamber area. I have torn off the brick hearth and face already...and would very much like to build a "Rumsford" masonry FP. Can it be done w/o tearing down the chimney? (Chimney is 12" square clay flue.) Thanks.

[Collin]

Need to check with a mason who knows local codes but I think your flue liner is too big.

[chimney doc]

Contact a reputable chimney sweep in your area. Many have now been trained in how to remove steel form (Heatilator/ Heatform) fireplaces and Rumford-ize them. I recommend you incorporate a stainless steel Rumford throat to a listed chimney liner. For instance, a 36 inch Fp can take a 9 inch stainless steel liner with the requisite insulation and still fit inside that flue without busting out the tile. Don't try to use existing flue tiles. Old, archaic material well past its time. Cannot take the heat, abuse, etc. Joints every 2 feet. Cold, heat sink. Stainless heats up quickly. round liner for better flow. Warm insulated liner performs better with less creosote buildup and easy to clean.

NFPA 211 calls for a 10:1 ratio btw fp opening to flue cross sectional area when sizing rectilinear liners and 12:1 for round. Most sweeps I know who Rumford-ize get terrific results at 16-22:1 ratios!

There is a trick to torching out those old steel fps so don't try it yourself unless the fire dept is standing next to you and you're wearing a hard hat for when it crashes down.

doc