Improved C-172 Cabin Heat

Power Flow Systems Improved Cabin Heat for Cessna 172/175

May 14, 2020

In accordance with our policy of continuous improvement, we are excited to announce a design enhancement that significantly increases the cabin heat output for our Cessna 172 and 175 second generation exhaust systems (our p/n, PFS-13204).

In the original design (dating from 2003), the cool air enters at the front left of the shroud, passes over the internal collector pipes which serve as heat exchangers, then exits to the cabin on the back left side of the shroud.

Unfortunately, this was almost a direct straight-through pathway. The Cabin heat SCAT hose connection would then come out of the left side and have to snake its way back to the far right side firewall where the cabin heat mixing valve is located. For most customers, the heat output of the Power Flow was considered to be acceptable, but some flying in extremely cold temperatures told us that they wanted an improvement.

With our new design, we have made a vast improvement by relocating the cabin heat output and forcing the air to take a much longer path through the collector assembly which acts as a giant radiator. This forces the air to remain inside the shrouded collector area for longer and greatly increases the available heat inside the aircraft's cabin.

The new design’s output is a 2.0 inch tube that is on the right side of the engine. 2.0 inch SCAT tube, clamps and an adapter to go from 2.0 to 3.0 inches are provided so that the SCAT can travel back in a more direct path to the cabin heat mixing valve on the right side of the firewall.

Our ground testing shows that we increased the heat output by 42% over the original Power Flow Systems design (from 100 degrees F to over 140 degrees) and by 27% over the stock Cessna exhaust (from 117 degrees to 140+).

Power Flow Systems Cessna 172/175 kits have been shipping with the upgraded cabin heat since March of 2020. Existing second generation PFS-13204 operators can purchase a complete improved cabin heat retrofit kit from us - it is our part number PFS-51724 and it is available now in our online store.

For a complete description of this new shroud, please see our YouTube video or watch below.

Old style cabin heat showing the original cabin heat flow design.

New style cabin heat air flow depicting airflow and the relocation of the hot air output.

Bottom view of the old cabin heat shroud design.

Bottom view of the improved cabin heat design.

Cabin heat output differences between our improved cabin heat design and the original cabin heat compared with the stock Cessna cabin heat output.