This unit has a new heat exchanger, Inducer, board, pressure switch.
The pressure switch stays closed with about .60" cold but slowly drops to .32 when the burners fire up. Not enough for the .45 required.
I tested this with my Amprobe electronic manometer. i T'd into the pressure switch hose and used the (-) port on the manometer
After this pressure issue, i went as far as removing the plate that the inducer mounts to and hi-temp siliconed it taking care not to block the little groove at the bottom for moisture to go.
The inducer gasket is the new one that came with the inducer. This improved my pressure slightly but did not fix the problem.
The gas manifold has a perfect 3.5" when fired up.
I also replaced the pressure switch with another new one in case I was just crazy. Also the instructions for the psi switch mounting are unclear. The best position i could find was wire terminals facing up.
Could it be something I did when replacing the heat exchanger? I installed it the same way that it came out.
I Need Help. Any Suggestions??
The unit had major problems with the heating and cooling side so we had to replace a lot of parts including the compressor.