I clean the electronic air filter for my furnace regularly in the dishwasher, but it never seems to work as well as it did when it was new. Do these filters wear out?
Your problem probably lies with your dishwasher and choice of soap. Using the dishwasher to clean electronic air cleaners is not a good idea as the water jets are too strong and the rack can bend the delicate parts of air cleaners. Secondly, most soaps leave a very fine white residue on the plates and wires of air cleaners. This film greatly reduces the effectiveness of the unit. You need cleaners that are good degreasers but, more importantly, rinse off completely, leaving no residue. If you have trouble finding specialized cleaners, concentrate on extensive rinsing with a garden hose and perhaps a little brushing with a soft paintbrush. Let the air cleaner dry thoroughly before turning it on again.