I have a Keystoker A-80 and use it November through about May. Once the heating season is over, I do absolutely nothing with it until late summer when I thorougly clean/vacuum out all the fly ash, and with a putty knife, I scrape the ash scale from the inside of the fire box and ash pit door, and the small amount of scale in the heat exchanger. Way up on top on the inside of the heat exchanger, I use a old broom with a shortened handle to brush down the fly ash from there. Underneath the ash/scale is next to no rust at all. I have had a little trouble with the door latch on the ash pit door, but after the first year I learned to oil that up once the fire's out, and then a few times throughout the summer. This will be my third winter with my Keystoker, and it sure beats all the work and dirt, bugs, etc of wood. A cold boiler, however would be another matter, as I'm sure it would attract a lot of condensation over the damp summer.