I've recently purchased and installed a Heatmor 100CB for my home. This model claims to be a coal boiler, but the dealer I purchased from said most people just burn wood in it. To burn coal, you buy shaker grates and then you can use coal. This will be used to heat my 2200 sq ft home. My question is - Does anyone have any input as to using a coal outdoor boiler? How much coal do you go through a winter? Wood is free, but time is money. Is coal worth it?