I have an older house which is not equipped with conventional ductwork. This makes it very difficult to heat in the winter. In the kitchen, we’ve installed a compact, natural gas heater. This heater is a ventless, single-stage heater. Because it is ventless, it creates an oily film on the windows in the kitchen. I have a pair of antique French doors which each have twelve small windows. These windows are time-consuming and aggravating to clean. In the summer, I rarely need to worry about them. During the winter, they are forever cloudy and in need of a thorough scrubbing. Because the heater is a single-stage unit, it blasts heat at maximum capacity unit it achieves the thermostat setting. It then shuts down and cools itself by blowing cool air. The constant on and off cycling results in unpleasant temperature swings. The ventless heater is also very temperamental and requires constant filter cleaning. At least once per week, I need to remove the two filters and meticulously clean them. If there is any debris clogging the filters, the warning light on the unit starts blinking red. When this happens, the heater will no longer shutdown. It keeps running on maximum capacity, and I worry that it might overheat. Overheating could damage the heater or even present a safety hazard. Once a year, the filter cleaning is not sufficient, and I need to take the heater apart and clean it with high pressure air. The pressurized air removes any buildup of dust. Unfortunately, this dust then fills my kitchen. I should perform this task in the summer, as a proactive strategy, when I can open the windows. Instead, I always wait until the heater refuses to operate properly, in the middle of the winter.