Just so that everyone is on the same page here because anyone who knows me, knows that I despise HeatMaster, Jake Friesen and Ryan Friesen for what they have done to me over the years, they cost me more money than any of you will ever understand but the big thing that they cost me was reputation and friendship with my customers, I take that very personally and don’t forget! With that being said, ticapa, that stove model was a major issue for them that caused multiple change outs, if the corrosion was caused by moisture then it was likely because the bypass was leaking and constantly drawing air through the stove, it will never be right until the bypass door is sealed permanently. The large space over the refractory and below the firebox bottom was a result of the designers not taking expansion and contraction of the stainless into consideration, believe me when I say that I personally have had to smash many of those refractories out to change them after they cracked to crap, that one seems to have been cut after production. Burning too hot, get the heck out of here, what kind of excuse is that, if the boiler is full of water then how could it possibly heat the stainless steel to the point of compromising that stainless in any way, you would certainly see permanent warpage well before the pitting that we see on that stove! I’m guessing that somebody got a deal on some Chinese stainless. I wish you the best and as long as I don’t get banned again for exposing the truth then I’ll be here to help you with information regarding your boiler.