Well let's see, I guess that I am the guy to answer this one, not real sure myself on the 20 year but I do know that most everything in life is Pro-Rated, there are wear items on the boiler that have limited warranties such as refractory, we will warranty it for 2 years and it should last 5+ years, we don't really know, Electrical is 1 year as with most electronics, we don't build those parts and must rely on the manufacturers warranty, no it does not cover on site repairs other than welding if needed and that would be contracted to a local welder, you mention Wood Doctor, I can tell you that at one time I sold for them and left for exactly that reason, the warranty sucked, this is not one of those companies, I personally am in Greenfield NY (Saratoga Springs), we just replaced an Auger on one of our chip boilers that the homeowner admits was their fault, they are being billed for my travel time with a spare Auger that I had in stock, we do pride ourselves on our common sense approach on warranty issues, do we give away the farm? No we do not as that would be bad business practice but we certainly do work with the customer to try and resolve the issues that will eventually arise in any mechanical device. I sincerely hope this helps in your decision.