Our house has a solid fuel back boiler as our only form of heating / hotwater and we now use smokeless coal exclusively.
Intially we had a 50/50 mix of smokeless and house coal as thats what the people that moved out left us. We have tried the following:
House Coal / Cheap Coal / B and Q / Petrol Station Coal on its own:
Cheaper for coal with a like for like quantity than smokeless (direct from the coal merchant), burns colder and quicker so overall more expensive. Generates a lot of dust in the house, generates a lot of ash, leaves deposits all over the boiler. Can be trouble to keep it lit overnight. Can be lit directly and easily with fire lighters.
50 / 50 mix of smokeless and house coal.
All the down sides of house coal on its own with the exception that it stays lit longer. Slightly warmer fire but not as much as you would expect.
Smokeless coal on its own:
Costs me £15.50 for 50kg delivered, gives out a fierce heat and will stay lit for a good 12 hours. Less ash as it burns “cleaner” and overall less mess in the house. Very hard to light, you need to make a fire with kindling to get the fire and chimney warm and then slowly add the coal. (Also you can use whatever sprays you have in the shed for the bikes and cars if your desperate. Clutch cleaner is v.good). Overall cheaper. Ash pan needs emptied twice a day, sometimes three times if your going mad with the burning of the coal.
If its a decorative little fire then I would burn the cheap stuff, its not important really how much heat you get as it will heat the room anyway. If its to do proper heating or hotwater then its worth sticking with the smokeless coal, once you get used to lighting it the difference is night and day.