A wood boiler. It heats the glycol in the house. We save money by burning wood harvested from a slough nearby, Kallie Slough. When this wood boiler burns down to ashes, the oil boiler kicks on. Jay, who is known to disappear for 1/2 hour randomly throughout the day, keeps the wood boiler going as much as he can. When Jay isn't in the house, you can assume he is in the garage, splitting wood, loading wood, or monitoring the wood!