See inside a packaged rooftop unit
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If you’re the kind of pro who likes to understand the mechanics of the technology you use or specify, this video is for you. In Building Operating Management, expert Ryan Hoger opens up a packaged rooftop unit (RTU) on video to show how both the heating and cooling components work.
After explaining the cooling operating of the unit, Hoger gives an in-depth description of how the propane- or gas-fueled heating section works. The heating operation includes several key parts:
- A gas valve controls the flow of the propane or gas. It can be a one-stage, two-stage, or even a modulating valve, and it controls the flow of gas into the burner.
- The inducer motor’s job is to pull air through the combustion side of the system. Air goes through the heat exchanger and then comes out through the inducer motor.
- Burners convert the fuel into flames that heat the air.
- Safety features include a pressure switch that shuts the unit down if air can’t move through and a limit switch on the heat exchanger that shut the unit down if it gets too hot.
- The heat exchanger includes five tubes of combustion air that exchange heat with the air that heats the building.
RTUs are a common way to provide heating and cooling for large commercial buildings, and in areas without access to natural gas, propane can fuel these high-powered units. That was the case for the Dutchess County Society for the Prevention of Cruelty to Animals in New York’s Hudson Valley. The 11,000-square-foot main building uses propane water heaters and is heated by propane packaged rooftop units. A new 2,000-square-foot addition will use a 7.5-ton propane RTU along with an energy recovery ventilator.