Air Pressure drop across evaporator coil

[Kelly]

What is the typical range of air pressure drop across home evaporator coils? Assume the coils are clean.

[HVAC Guy]

Do yourself a favor and remove any baffle plates mounted under the evap coil that forces *ALL* airflow through the coils. This will reduce the resistance to airflow that exists UNNECESSARILY during the heating season caused by the coils and associated baffle or restrictor plates.

I did this a few years ago in my furnace, leaving only a couple of thin brackets to support the coils within the plenum. Even for summer A/C use, this does not seem to have an impact to household cooling, and the reduction in resistance allows more airflow during times when just the fan is running, which by itself is able to cope with our now cooler summers in the great lakes area (if not most of the mid-west).

So stop wondering if your coils are causing too much restriction and modify the situation so you allow more airflow around them, if only during the winter heating season.

I'm surprised that even modern furnaces, with the insane lengths they go to with sensors and expensive control boards to maximize efficiency, don't allow for or have built-in ducting that can be switched in and out as needed to duct air around the coils when cooling isin't called for.

[TimR]

Some commercial equipment has bypass dampers. Not so much in residential I guess.

Remember any air that did not touch your coil did not get dehumidified.