May 05, 2020     Heat/Defrost - (30 hours)       Category: Heat/Defrost

We decided not to buy and install the heating/defrost air control offered by Glasair Aviation. Our custom heating and defrost system involved designing a sheet aluminum heating/defrost control box. After initial design sketches, engaging construction by a sheet metal expert, followed by tedious and extensive modification, and finally fitting and installation on the cabin firewall just to the left of the "dog bowl" projecting aft in the firewall. The control box fastens with screws and hi-heat self-locking nuts through the firewall. We applied a red silicone seal to prevent air leakage at all seams of the control box. The pivoted flapper valve connects to a push-pull Belden cable control mounted to a bracket on top of the front center tunnel for easy reach by the pilot or copilot. Pulling the control out feeds the increasing flow of defrost air to two 10" wide plenums on the pilot and copilot sides of the glare shield. This will offer so much more defogging and defrosting capability than many GA aircraft. The control box also directs heated air down to a metal 2" Y fitting which feeds air down.

Stratford designed a heater control mounted on the firewall in the engine compartment using aluminum control boxes similar to what is common in RVs. The heat for our Sportsman is produced by two muffs which are part of the dual, left-right Vetterman tuned exhaust system we were lucky to get with the 850-hour engine we bought from an RV-6A builder. We chose to not buy the Glasair factory 1 1/2" diameter heater duct/control system which would have been much simpler to install. Stratford's design using 2" SCAT ducting will produce a larger volume of heat for the pilot and copilot defrost/defog use as well as extra flow aimed at Stratford's cold feet! We will control the heat/defrost system with two push-pull controls, one for heated air volume and the other directing heated air to the two, long lovers in the glareshield or, in varying flow, or downward to. the floor area.