Heater Installation and Firewal Sealing

Another builder, Dick G, also from Texas, did a great job spec'ing out his heater installation.  When I saw his pictures, I knew I would have to follow suit.  First order of business was to mount nutplates onto the heater unit, which consists of a small heater core mounted to 2 large computer cooling fans, as shown below.

Also appearing in the inlet and outlet barbs are some 1/4 inch aluminum tubing which I pre-bent before installation of the heater hoses.

After determining what I hope to be a good location with respect to the throttle cable and the as-yet-to-be-seen Skyview avionics, I installed the unit with #8 machine screws and aluminum tubes.

The next brilliant idea I also stole from Dick.  He had installed a small ball valve on the passenger side of the cockpit to regulate the effectiveness of the heater from completely off to completely on and everything in between.

Plumbing complete on the return side of the heater.

The return line comes up through the instrument panel shelf, adjacent to the map box (not shown) and exits the firewall via a brass bulkhead fitting, shown below this picture.

Return heater line exiting the firewall.

 The inlet side of the heater as it emerges from the firewall is shown below.  Again, a bulkhead fitting is used to manage the firewall penetration.

As usual, the strain relief for the hose via an Adel clamp.

Firewall side of the inlet heater line.

The proposed routing of the inlet heater hose that will run beneath the engine on its way to the pick up point on the head.

Shown below is the engine being pulled from the firewall, hopefully one last time, prior to sealing all rivets and unused Rotax nutplates.

  

I had reasonably good luck using some shop brushes cut down to about 1/4 inch to apply the Proseal.  I tried a new technique to facilitate spreading it around.  Previous threads on VAF addressed the use of a thinning agent to make for easier application of Proseal.  According to one poster, the manufacturer of ProSeal allows for the use of up to 15% toluene by weight to thin down the product.

After mixing my goo, I put a small bit of Toluene into the mixture and what a nice surprise, the Devil's Snot actually became downright friendly to work with.  Now, if it just cures like the unthinned product, I will be very happy.

Every rivet head and exposed nook and cranny got a dab, more like a brush, of Proseal.

Now we play the waiting game and see if it all sets up as expected.

Fast forward two weeks and the toluene-thinned ProSeal is finally cured...but it took a lot longer than I was hoping.  Nevertheless, it is all good and dry and the final install of the engine and its subsystems is under way.