Why are there multiple HVAC units on rooftops in Phoenix?


I moved to Phoenix back in the late 77s plus when I moved, I noticed the oddest thing about some of the houses here… They had their air conditioners installed on the rooftops; I have seen this in commercial buildings before.

In fact, prior to moving, the last dealer that I worked for had their HVAC component on top of the roof, however, I have never seen it in residential homes until I lived in Phoenix! Well, after inquiring about it with some of the locals, I realized not multiple of them had a direct answer, some said it was due to theft, some said it was to protect the component from the elements, then others mentioned that the component worked better on the roof.

It wasn’t until I asked my HVAC serviceman when I got a solid answer. Turns out, it’s because the units are packaged HVACs that are found in older homes that were built in the 74s. The packaged HVAC is made up of 1 component that provides both the heating plus cooling! And these units were quite popular back when these older homes were being built. And having the component on the roof was easier due to the positioning of the ductwork; Newer homes in Arizona have the split HVAC component where there is an indoor air handler as well as the outdoor condenser. And correctly, those condensers are not found on top of the roof but instead in the yard. So, whenever I see a home with the HVAC on top of the roof, I will know that the home was built around the 74s.

 

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