Two Compressors One handler & thermostat

Good Afternoon All,

I am located in Houston where it is HOT, HUMID, and A/C is critical. I have only been inspecting a little over a year and only have 150+ inspections so I’m sure there is a lot I haven’t seen. Anyway, I came across something new today…(and I see a lot of HVAC units down here even with my limited experience.) There were two condenser units and only one thermostat. It is a 2 story house, thermostat was downstairs near the bottom of the stairway…stairway is open to both levels of house and the only return air vent is at the top of the stairs. (One furnace/handler in attic.) Both compressors were running, differentials were great both upstairs and downstairs. House was very comfortable at 2:00pm with temps in the upper 90’s and ridiculous humidity. (Feels like temp over 100.) The house is vacant and close by so I can go back and look at stuff if needed. My questions: What am I missing? What am I not seeing that I should? What type of set up is this and is it common? (Oh…house was built in '77…one condenser is 2003 and one is 2014…both Rheem.)

How many coils of what size did you see? What were the sizes of the condensing units? What was the size of the furnace/AHU?

Photos would be useful.

Yes, we have occasional instances of combination units here, though they seem to be becoming less common. It’s been a few years since my last one, which was a commercial 3-phase condenser mated to a pair of siamesed AHUs.

Thanks Chuck,

I will look through my pics and pass along for clarification. If you haven’t seen one in a while I’m not surprised this is my first.

How many refrigerant lines present at the condenser and how many at the air handler. If you have 2 sets at the condenser and only 1 at the air handler then there probably is another air handler. You would not believe some of the places I have found air handlers hiding.

I would have been looking forever lol…I haven’t seen one air handler and 2 condensers yet

At the air handler, did you have 2 A coils or just one set of lines? I have never seen this configuration out here in CA. Now in my home I have 2 air handlers one upstairs and one down on separate thermostats. Outside is a single cabinet with 2 separate compressors.