dirty filter and condensate management

[John Dirks Jr]

Could an air filter that is really restricted with dirt cause the system to mis- manage condensate?

For instance, the system would be so hungry for air that it would pull a significant amount back through the condensate drain line and thus cause condensate leaks through the system cabinet.

[Marc]

I've known a few primary drain pans to overflow because of a combination of restriction at the drain opening and blower suction. Shut the thing off and it drains like Niagra Falls.

Unusual for sure.

[John Dirks Jr]

I've known a few primary drain pans to overflow because of a combination of restriction at the drain opening and blower suction. Shut the thing off and it drains like Niagra Falls.

Unusual for sure.

Thanks Marc. I did a bit more searching and found one source that said the evap core freeze up caused by dirty filters can melt off in a manner that bypasses the drain pan. That could do it too I suppose.

[Marc]

Its common here. When it freezes up, the ice can expand beyond the dimensions of the pan which means that when it melts the ice water misses the pan and floods the bottom of the air handler (for horizontal flow units). The insulation at the bottom gets wet and will never insulate well again, even after it dries. In the summer season, you can identify the ones with a history of freezing up by the condensate dripping from the bottom 2 inches of the AH.

Marc

[inspector57]

Yes, John, dirty filters can cause both overflows and freeze ups.

Was this coil on the pressure side or the suction side of the fan?

[Tom Raymond]

This is what the aftermath looks like.

Dirty filter. Frozen coil. Primary drain was a pump, it failed. No secondary drain.

Click to Enlarge

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Who puts a pump on an overhead unit? Knucklehead.

[John Dirks Jr]

Yes, John, dirty filters can cause both overflows and freeze ups.

Was this coil on the pressure side or the suction side of the fan?

The coil was on the pressure side as usual.