Sep 06, 2018 - 12:00 AM
We recommend the Hayward Universal H-Series Low NOx Pool Heaters during the winter for your area. For an 18x36 pool, you would use the 250,000 BTU heater. Most heaters, and heat pumps are meant to be winterized. However, you might be able to use the heater as long as you don't allow it to freeze up. A heat pump would have the same recommendations as far as winterizing. The heat pump you could use is the Hayward HeatPro Heat Pump, 140,000 BTU. For more technical information, you could call Hayward.