Wasps, mud daubers, birds and rodents pose a serious threat to the furnace or tankless water heater on your RV. They can enter through the furnace or water heater vents and cause serious damage by building nests that interfere with air flow. Camco 42144 (Model FUR 500) Flying Insect RV Furnace Screen fits Atwood Hydroflame furnaces that do not have access door, and the exhaust vent of Girard tankless water heaters. As Camco offers several furnace and water heater screens, consult size and photos to confirm this screen will fit your furnace or water heater vent. This easy-to-install screen will help ensure that your furnace or water heater vent stays free from costly invasion by unwanted pests.