Had a two story flip today one furnace down stairs in a closet off of a 1/2 bath. Worst mess I have ran across in a while.
The furnace was cycling on its limit switch according to the blinking lights on the control panel (York) I had absolutely no air flow at any register could not feel anything moving. Removed the blower front of the furnace and exposed the filter section above the blower this is a downflow that I am referring to. The filter was hanging down on top of the blower housing and all of the construction trash that you can imagine was blocking the return air duct from above. This home was using the floor space between the two levels as a return chase with return air grills on the hall floor upstairs; two of them. I thought Well I’m done with this one turn it over to the HVAC guys.
I wasn’t done yet my gut was saying look a little closer.
I did not like the way the flue vent was traveling right strait above the furnace and I had already established that the floor space above this furnace was being used as a return chase. So out comes my trusty Co meter and I test low and behold I am picking up a trace of Co all through out the first level. There was a high wall return air grill down stairs living room that allowed me to see inside the chase above the furnace Guess What??? There is the flue pipe inside the return air chase. This Is a NO NO NO. There was a pipe connection visible within this chase I am assuming that was where the Co was escaping in to the return.