The honeywell IAQ will run the blower motor in first stage and will allow between 1 to 3 degrees of over cooling to satisfy dehumidification setting.(1-3 degrees past set point) Slowing down the blower allows the system to remove much more moisture.
Heaters (elect, HP or Gas) do not dry out the air... where's the condensate in heat mode? People get this perception when the unit runs a lot because the air gets dryer... but actually it's the other way around. When it is cold outside, the humidity is much lower and as a result of the low temperature outside the heater runs more. The air is dryer because of low outdoor humidity.
Now, cooling is another story... One solution to excessive moisture removal in cooling could be to increase the airflow... assuming it will increase. The new 5 ton system on the old 3.5 ton duct may be have restricted the airflow to the point of excessive latent moisture removal.
Low airflow can also exasperate ozone production in EACs.
Until I see some actual humidity and temperature numbers posted, both indoors and out, I would attribute the "dry" symptoms to something other than actual low humidity levels. It just does not ring true, from a psychrometric standpoint, that a heat pump system running in a humid climate like Florida is causing a house to dry out to where it irritates nasal passages and throats. If this is indeed a heat pump, we do not even have combustion air issues to discuss. Leaky attic ductwork, perhaps, but even so I'd want to know what the outdoor dewpoints are running at when the "dryness" complaints are lodged.
I would be looking for other irritants.
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.
I have to agree based on what the OP stated and the fact that with the clean effects turned off the symptoms abated, I lean toward O3 sensitivity.
Originally Posted by shophound
I think we should revisit the cause of high ozone. In my opinion it is low air flow thru the air cleaner due to the up sizing of the equipment and not upsizing the duct size for the higher air flow.
IAQ in residential ?
Originally Posted by ArmyMom&Wife
Thought you might want to read this before you make any harsh decisions.
What ever happen to fresh air ventilation and a good simple air filter? We have to make it so complicated and we do not even supply any fresh air! This is sad story. All indoor air quality experts agree the very home needs a clean, fresh air change every 4-5 hours when occupied. The indoor humidity should be <50%RH.
Check out ASHRAE/EPA/American Lung Ass. web sites for info. Regards TB
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"