Medium Size 15 Ton RTU – Video Transcript:
I want to give a brief rundown of a rooftop unit or RTU heating and air conditioning unit. Basically, it’s a package system that has everything for heating and cooling for a building, in one package. We have several of them on this roof these of the smaller ones and we’ll just go through quickly a medium sized this is a 15-ton York/Johnson control rooftop unit. We have an intake air hood for the economizer here. There’s a discharge air hood/relief hood for letting out excess pressure from the building, mounted on the return air duct. This particular unit is ducted off the front horizontally and into the building. Inlet air comes in through here. There’s an outdoor air damper and a return air damper, a set of filters just before the airflow goes through the evaporator coil, evaporator coil here. The fan motor draws air through the evaporator coil. There are two thermostatic expansion valves on the refrigeration system connected to two separate coils that are actually in that one coil. This unit has two separate cooling systems in it. We have the blower motor, the blower here, motor drive here, variable frequency drive and this helps us to I reduce inrush current, helps take a little wear and tear off of the fan by not starting it all at once quickly and also gives us the ability to regulate the speed of the fan so we can precisely dial in what the air temperature differences are across the piece of equipment. In either heating or cooling mode, the fan blows in across the heating heat exchanger which we can’t see without disassembling a whole lot more. This unit has one induced draft fan. This is a two-stage heating unit, so it has two separate ignition modules, two gas valves, and two burner sections. The power and control portion is in here and this is what we refer to as the brains of the system, this is York/Johnson controls Simplicity Controller. It controls all the functions of the unit. This unit has two separate condenser coils, two separate condenser fan motors, and two separate compressors for the cooling, 2-stage. That’s a brief overrun of a medium size 15-ton package rooftop or RTU.