Thank you for you using Aprilaire in your home comfort system.
I am somewhat perplexed that your system had been operating for 14 years with insulation restricting the air flow. Normal installation does not necessitate the blockage of air into the humidifier. This may have been done to prevent water leaking from the humidifier in high static pressure within the duct system. I would recommend having an HVAC contractor look at the system to determine the reason for the use of insulation; it was not for filtering the air.
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