On 9/28/2019 12:11 PM, Davej wrote:
I hate to interrupt the ongoing political trolling but...

If an HVAC system was "appropriately" sized, what maximum duty
cycle should be seen? In other words if my upstairs AC runs
continuously -- that probably means it has a problem or is
undersized. But then, if it was working correctly and was properly
sized -- what duty cycle range would you expect? Thanks.


Depends on a lot of factors. Upstairs tends to be hotter for two
reasons, heat rises, also it is directly under the roof and solar load.

What was the design criteria? Phoenix will have a different mas
temperature than Concord NH. Was the appropriate temperature used?
Most units are sized for a 20 degree drop from maximum expected.

On the hottest days of summer I'd expect it to run near constant, less
so at night. Cooler days can easily get down below 50%.

Check to see what is running. It is possible the blower is not shutting
off yet the condenser outside is cycling as expected.

What is the thermostat set for? What is the actual temperature?

Also, if it is 90 outside and the thermostat is set to 55, it is not
going to shut off and it won't get down to 55 for another couple of
months, depending on location.