My house has 2 zones for air conditioning (Upstairs & Downstairs) with 2 different air conditioning units.
We have Nest energy saving thermostats, which are great for keeping track of energy history, and I noticed that the downstairs AC is virtually never on, and the upstairs AC is on almost constantly.
This is mysterious to me because we clean our air filters constantly (Including the outdoor AC unit itself (Once per season). NOTE: I live in Suffolk County, New York
Observations:
0) There is cold air coming from the upstairs vents, although it isn't at a very high rate. There are vents downstairs that have far higher (Around 2x) air flow.
1) The thermostat can't reach its set point temperature. This situation lasts through the day (Check History for more on this):
with the upstairs temperature never reaching the set point, and always staying above it. (Note the 80 on the side is the current temperature)
2) The downstairs thermostat is in sync with the upstairs thermostat usually. (They are also both on at the same time) to minimise heat gain die to convection.
AC History:
Upstairs:
Downstairs:
Specifications:
Unfortunately, there are no records of the AC system that I could find, but I did manage to get this from the back label of the AC unit that is always on: C 249534. I don't think I can get more information without actually taking the panel off.
There is also some kind of machinery on the inside (I'm not entirely sure what it is):
Further Away: (The top panels say Ultra 80 & the bottom labels say Armstrong Air
There are also electro-static filters (Which according to my dad contain the only filters in the system, although he might be mistaken, I'm not sure)
Are there any obvious red flags with this set up? What is the most likely cause of failure given the set-up of the system? Are there any additional filters that I didn't know about that aren't being cleaned? Are additional specs required?
Best Answer
It looks like the air handlers are both in the basement. There will be a fairly significant friction loss due to the added distance of the second story air ducts. If the ducts weren't carefully sized and balanced from the beginning, this could impede the airflow.
Another factor could be the return air. If the upper story does not have its own return air, then the returns will be sucking air from upstairs down to the lower floors when the system is on.