As the days get shorter and temperatures turn milder, most HVAC systems are taking a well-earned vacation. For a short while, a cool breeze through open windows will be enough to keep us comfortable in our homes. But soon, homeowners will switch their thermostats from cooling mode to heating mode, and some of them will unfortunately discover their HVAC system does not heat. It's time to pull out those extra blankets and make the call to a service professional sooner than expected.
There are many types, manufacturers, and sizes of commercial HVAC systems which can make it difficult to create general guidelines for repair procedures and estimates for hail-damaged units. This guide uses the most common "light commercial" rooftop units (RTUs), which are 5-tons, 7.5-tons, and 10-tons in capacity, for estimating time to repair or replace.
Residential indoor air quality, historically, has not been a major concern because the envelope and window leakage provided inhabitants with sufficient outdoor air. Older residential buildings are sufficiently leaky such that infiltration alone can meet the minimum outdoor air requirements for residential ventilation. In an increased environmentally conscious society, many individuals have become more aware of their resource consumption, and are implementing enclosure draftstopping, attic insulation, and window replacement.
Mechanical ventilation systems have evolved from passive gravity vents (circa 1900) by adding modifications to improve comfort, occupant health, and energy efficiency. Early on, the maintenance of the system basically related to making sure the furnace was on and the windows would open. If you were lucky the school might have draft deflectors on the windows so the wind would not blow directly on your head.