Question: Are there any standards for Coal Quality when used for home heating? Answer: Yes, there are vast differences in ash content, clinker formation, etc. One coal that has always had a great reputation is Old Company Lehigh. Depending on the particular stove, this difference may be accented. For instance, the European hopper-fed coal stoves required a high-quality low-ash coal. Other "batch fed" stoves may be less sensitive. Most companies will give you a chemical breakdown of their coal and explain what the numbers mean.