I purchased a house with a Vigilant 1400 Multi-Fuel Stove and have been burning wood throughout the winter but noticed the burn will not last for more than 4 hours at a time and I am ripping through wood. I have the shaker grates which limits my space within the stove. Could I remove the coal shaker and be ok building a wood fire directly on the sand on the bottom of the stove to allow for better/longer burns or does it need a conversion kit? It has a fireback but for coal. Not sure if that matters.