Honeywell Perfect Window HR150 Product Data page 12

HR150, 200, 205; ER150, 200 PERFECT WINDOW™ FRESH AIR VENTILATION SYSTEMS
Inspecting Exterior Hoods
Inspect exterior hoods at least monthly. Be sure exhaust and
fresh air supply hoods are not blocked or restricted by leaves,
grass or snow. In winter, be sure snow does not block hoods
and frost does not accumulate on wire mesh bird screen.
68-0171-9
IMPORTANT
Blocked hoods can cause house/building pressure
change that can lead to possible combustion product
spillage from heating appliances.
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