Shawn Forsythe
RIP
Because the accumulation is primarily dust that is carried within the airborne water and air, no screen will be likely to capture that which condenses upon the primary exchanger fins, or the very fine particulate dust, without being also quite restrictive. You can't use traditional filter media without the filter being quite large, and a simple screen won't be fine enough to capture much more than part of it.
The answer is having three things going for you;
1) An easy means to determine when the exchanger is loaded, but not beyond safe levels for all components and/or impinging on performance. (A pressure manometer tapped in before the heat exchanger)
2) A relatively fast and easy process/procedure for cleaning the primary coil.
3) Lessen the amount of contributory "sticky" materials that will end up on the heat exchanger (use your blower lube spray judiciously)
The answer is having three things going for you;
1) An easy means to determine when the exchanger is loaded, but not beyond safe levels for all components and/or impinging on performance. (A pressure manometer tapped in before the heat exchanger)
2) A relatively fast and easy process/procedure for cleaning the primary coil.
3) Lessen the amount of contributory "sticky" materials that will end up on the heat exchanger (use your blower lube spray judiciously)