HI. I am a Wooddoctor retailer in Oneonta/Milford NY. I have sold several convertors and have two in stock for sale. I have other wood boilers for sale. I have heard nothing about needing a welder related to Wooddoctor. Thats false. They are boiler plate. Warranteed for 30 years. Two blowers. One forces fire down thru fire brick. Second blower pulld smoke thru chambers. This unit is 2 times as heavy as Global Hydronics version. That must be converter needing plumbers. That one is Eco Burn. Anyone needing info , please call 607-286-3474. Frank Gambardella. Merry Christmas.