The size of the blower whether 1400cfm, 1200cfm etc has nothing to do with the high speed heating airflow.. If the second stage airflow is waking you up either you are a light sleeper or the velocity of the airflow for the 2/stage is high due to a undersized ductsystem or the unit is too large for the home or atleast the ducts..Load calculation??? Duct calculation???
A variable speed motor will try to move the correct cfm whether or not the ductwork will carry it, if duct can not carry the cfm it can make the velocity of the air thru the duct to become too high which can lead to objectionable airflow noise...
If you have a infinity control the TESP can be checked to see if it is running too high at that cfm..
This objectional airflow noise can also happen in cooling if the cooling cfm needed is the same or high than the cfm needed for the high speed heating..
As stated the TESP need to be checked and if too high, the ductwork needs to be checked and upgrades are needed to lower the TESP to an acceptable level which will also make the airflow go thru the ducts at the appropriate velocity, this will allow the unit to be as quiet as possible..
Also when the TESP is high the VS will ramp up to a high rpm which will cut any savings advertised with a VS,, this may also lead to premature VS failure..
I hope some of this info may help..
P.s. A totally correct TESP would be .5 at the highest cfm the system will operate at.. However, I have found that these unit are still quiet in most instances if the TESP is below .7, anything over that the airflow starts to get alittle noisy..
[Edited by Advanced Response on 02-19-2006 at 12:16 AM]