RH Humidity Problems - Help!
I'll try to keep this as short as possible.
I have a 3,000 sq ft ranch style home in western Canada. We had new AC system installed 5 years ago, including ductwork in the attic of our home. 2 AC units were installed, (both 3 ton). One provides cooling for the LR/DR/Hallways and Den and the second does the bedroom wing. From day one we got extremely cold air and excessive cycling. In addition, the RH was never lower than 62%. After some discussion with the contractor, it was discovered that the manual J called for 4.2 tons (Supplier of the equipment did the manual J but didn't provide it to the contractor, just the recommendation for 6 tons) . The contractor discovered that the air handler for the LR unit was sized for a 4 Ton unit as was the duct work. The bedroom air handler was for a 3 ton and the ductwork was also sized for a 3 ton.
After a meeting last month the contractor said the following was the fix:
1. Remove the bedroom 3 ton unit and replace with a 1.5 ton unit and matching 1.5 ton air handler;
2. Remove the 4 Ton air handler from the LR unit and discard. Use the 3 Ton air handler (from the bedroom unit) connecting to the 3 ton outdoor unit - existing (this set up will give 4.5 ton of cooling capacity);
3. Balance air flow and adjust ECM air handlers to optimum speed.
With this new setup, cooling comfort has improved. Airflow has been reduced significantly and we no longer feel blasts of cool air (the "meat locker" effect). There was some discussion during the recent installation that we might not have enough "static pressure" with the new setup given that the ductwork was 3 ton for a now 1.5 unit compressor (bedrooms) and 4 ton for 3 ton compressor (LR/DR/Den). We had no further discussion on this.
I had asked the contractor to make sure they sized the new units correctly and asked that they upgrade me to 2 stage units. I reasoned that in off peak running times, the Rheem units running in stage 1 would dehumidify without lowering the temperature much below the set point on the thermostat. They said the cost would be excessive as their remediation plan involved using some of the same equipment, wiring, setup, etc.
I don't know where to turn at this point for a solution. I feel the RH of 63% when the outdoor is 60%RH (+28C) is too high. Crackers in our cupboards are soft and it just feels "wet" in the house.
Anyone have ideas as to what is wrong with out setup and what it will take to correct it?