Why wouldn't Scrooge permit the fire in the counting house?

Coal of the time was quite expensive. Scrooge detested expense and would put some coal on his fire in his room and barely a who lump was aloud on Bob Cratchits . Scrooge would prevent Bob using coal by placing the coal scuttle in his room so Bob did not have access to it. This is why Bob is always portrayed as warming his hands on the candle at his desk to keep warm and why Mrs Cratchit hated Scrooge