Currently my HVAC system has this inside it: https://www.discountfilters.com/air-filters/bryantcarrier-kfafk0212med-2-pack/p110138/
It's a washable mesh basically...and it doesn't seem to offer much protection from...well...anything. Seems like the only thing it could stop is a golf ball. Says "Merv 4".
I want to get a Merv 13 disposable filter to hopefully help with my seasonal allergies...found one on Amazon that will fit (it has a weird size...couldn't find something that size at Lowes). Seems much more substantial...looks pretty solid from the pictures. My question is will this hurt the furnace at all with the (I imagine) reduced airflow from the new heavier filter?