Well, that does not sound good, it is an updraft boiler, so only way to reduce smoke is turn down the fan when loading. I would not shut it off just put it to min speed, and open the door slowly.if the fire is idling and not burning you dont want it to backdraft opening the door. Use a respirator when loading the dboiler, af wood smoke contains a list of tiny particulates not healthy in a small space.We got a UNI 15 and had it installed in our basement for our in-floor heat. I only have 40 gallons of hot water storage, so a lot more would have been a good idea. My main beef is the smoke coming out of the door I need to open to add wood. I added a draft booster to the exhaust chimney, which itself has problems. Having storage would mean I could just load it, burn it all up then start it up again later when there would be no smoke to escape.