I've found that housecoal burns the best on our back cabin range and have had the same 'experiences' in using it. I accidently discovered a way of getting rid of the tar, I left the damper open too long one day, when lighting the fire, and set fire to the tar lining the flue pipe! Apart from completely covering the marina with a thick, black smoke-screen there were no untoward effects. I just shut the damper and the sizzling in the fluepipe and the smoke died down almost straight away!I still burn housecoal, but often mix it with phurnacite or preferably, small anthracite nuts.