Research from the Gas Research Institute indicates that some ventless gas heaters are oversized for the rooms they are intended to heat. This can result in flue gas and water vapor emissions in excess of what the area can exhaust through normal ventilation and exfiltration in a certain period of time.

How much moisture does a ventless heater produce?

However, consumers need to know that the combustion process produces water. A 20,000 BTU vent free heater will produce about ¼ gallon of water into a living area each hour.

Do gas heaters create moisture?

Gas heaters cause condensation in winter “Hot air holds a lot of moisture, and at night when the air cools down, the moisture condenses on the walls.