Applying masonry stove principles to traditional Kiva fireplace design


We are installing a traditional kiva fireplace from Adobelite (UL Listed) in a commercial venue at 7000 ft. For wood energy efficiency and thermal performance, I wanted to apply some masonry stove/rocket stove principles including: a serpentine flue by pass, secondary gas combustion in secondary chamber with glass window, preheated secondary air, and one serpentine flue channel descending down through a bench and then up and back to the main 12" chimney. I am curious if anyone has had success at elevation with these design principles. I am particularly interested in what I can do without including a draft inducer, however I would use one to accomplish the project. I understand that I would need to seal the main firebox with a door to control/limit combustion air, and have any hope of visible gas combustion in the secondary combustion chamber.

@LivingArtSystems, thanks for posting this interesting question.

You are correct that having a firebox door would be the first step towards being able to achieve the possibility of a longer heat exchange pathway for the smoke to travel before leaving the building. An open fireplace does not provide enough of a funnel for the air coming into the systems and combusted gases and would likely smoke back if the smoke is challenged to go through a longer pathway.

A bypass damper would be the next step where you could toggle between a direct exit for an open fire and where you could easily induce draft in the chimney, and a masonry heater mode where you could close the doors and send the combusted gases through a longer masonry heat exchange flue path to extract and store the heat generated so that it could continue to radiate in the space long after the fire has gone out.

The basic idea would be, very conceptually speaking:

The drawing lacks necessary clean outs and the shut-off damper may be optional with an air-tight door and clean outs.

One challenge that you would have would be maintaining the UL Listed quality of the original unit with these adaptations. Another challenge is the lack of readily available parts, including the inline bypass damper, to make this work.

If I was to approach this project, I would approach it more as a masonry heater from scratch with the kiva design in mind as I create the heat exchange pathways and final plastered volume. I would design it to meet the masonry heater code in the building code and therefore not require a UL Listing.

It is a neat product and cool how they provide you with the pre-made ferro-cement skeletons.

My two cents. Anyone else?

The corner heater configuration is the more traditional starting place for a masonry heating approach. Stepping in the facing volume and plastering with the clean lines would approach the kiva style.