This is my first winter closing the pool with the Hayward H100ID1 NG heater. The system has been disconnected with the pump and filter put into storage, but the manual for the heater doesn't give any detail about winterizing it, which I plan to leave sitting in place beside the pool. There doesn't seem to be a drain plug of any kind, and the way I plumbed the inlet and outlet with PVC suggests to me there could still be water inside the heat exchanger. Do I need to take extraordinary measures to make sure as much water as possible is out of it? Insulate and cover it? What are some suggestions from others with this heater in cold climates?