A knotty problem. Even intermittent dry heat can cause condensation, as us humans loose moisture to the air, along maybe with your timber store, when switching on heat raises the air temperature. Warmer air holds more moisture, and when you switch off and leave you may well get condensation on heavy metal - a cast iron table, say. This can also happen with changes of outside air temp. if the building is not insulated.
My favourite is a dehumidifier of the dessicant variety (Meaco Zambesi). This also generates a bit of heat as a by product of dehumidifying. Not too expensive to run, and works even when the air is cold. It also samples the air briefly every 30 mins, and if not needed goes to sleep for another 30 mins. Keep relative humidity below 60% to prevent rust.