Have to say that the masonry heater that we had constructed in our home is one of the best investments we could have made! Love-love-love it! Heater works and heats as it should.....as long as you never open the doors after the fire is lit. That being said, I have a question for those of you much more knowledgeable than I/we. We have a problem with smoke and ash billowing into the house when the door is opened to add wood. In investigating this, we have come to the tentative conclusion that the makeup air piping of 4" in diameter (which runs under the concrete slab and radiant heat tubing) is not large enough. According to the geothermal heating guys (who we talked to when it was suggested that there might be a negative pressure issue - house is definitely NOT sealed tight yet), a 4" pipe is only capable of moving something like 30cfm of air and what should have probably been installed was more like an 8" pipe which I understand can move an exponentially greater amount of air and would correct this problem. At this point, digging up the concrete slab and severing heat lines is not sounding practical, feasible, or appealing. Do any of you happen to know of some sort of fan or other solution that could be used to boost the airflow to send the smoke up and out?? We have a four socket electrical plug on one side of the fireplace that we could plug into if needed.

Have included some construction pics for reference. Cleanout above mantle and below heated bench on front, electrical on side without heated bench, two cleanouts on back. Top ring has since been attached to ceiling and doors are on.

Hope that all makes sense! Sincere thanks to you all in advance for any help that you are able to offer.

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