Two years ago I replaced an older ('89) heat pump in a condo that I rent out. At the time, the salesman recommended increasing the tonnage of the unit to 3 tons, but he didn't do a load calc or balance that I'm aware of. I did specifically ask if the duct work was adequate for this increase and he said it is. (If I were to do this again, I'd sure insist on duct sizing and load calculations with hardcopy handed to me, so I could verify the recommendations... live and learn!)
The tenants at the condo have had problems with the system off and on during these 2 years. Several times now, the system has frozen up on especially hot days, or when they've returned from vacation and tried to bring the air temp down from a high, mid to upper 80s setting, to a normal setting, 77 or so.
When the AC tech has come out to investigate, he's simply said they need to do a better job of cleaning the air filter, and shouldn't run it for too long at a time. I happen to know for sure that the air filter is being kept pretty clean - they replace it every 30 days like clockwork (better than most people, including myself!)
Also, last week, when it hit 105 there, the system froze, even though it was a brand new filter.
Now I'm in a debate with the AC company, where I am stating that I think the return duct was undersized, but they insist it is not, and the problem is dirty filters and poor maintenance.
Here are some of the facts and figures:
Rheem RBHC17J furnace/blower
Rheem 10PJB36 heat pump
1100 sq. ft condo with vaulted ceilings in half, lots of single pane windows and sun heating. Located i nSaanta Clarita CA, where it is typically 95+ and sometimes 100+ during summer.
The air return is a 14 x 25 inch grille leading into a 14" round flex duct, with a pretty straight 6 foot run into the plenum.
So, I have a few questions:
1) Is the 14" flex duct air return adequate? What additional info is needed to answer this question for sure?
2) The maintenance manager for the AC company is meeting with me on Thursday to inspect the system. What should I request at that meeting? Static pressure and air flow measurements? Inspect fan settings and coil cleanliness?