Cabin heating System

My Andair On/Off selector valve needs to be accessible from the pilot seat. After sitting in the plane I found a spot that works well, the valve has to be pointing sideways for open and my elbow can’t notice it. When its in the OFF position I can feel it.

That’s a good choice. I carefully marked it out and spent some time inlaying the valve body so it would be flush as you see in Pic 2. Nice job eh?

Pic 3 is me later filling in the valve position with pour foam. This position thing turned out to be very tricky. The valve is made to turn a certain way and that was not matching my plans!

More modifications are required.

You could say this is part of the fuel system rather than sitting in the cabin heater logs. Ok, you are right. My thinking is that this was part of the work flow as the heater has to play nicely with where this valve goes.

Andair selector parts

Inlayed body

Fill and try again

Now for lots of little details. Pic 1 shows that I’m setting up the heater box and have found the extension to operate my Andair on/off main fuel valve is too close to the box. See the purple rod almost touching the box?

Everything is tight here so that I retain the maximum possible space for the passenger.

This was an easy fix.I lopped off the corner then later floxed on the flat piece of glass you see in pic 2 and then a tidy up.

Oh you might notice I now have a pipe inlet opposite where the eyeball hole is on the back seat. This was about three cure cycles over a day or so. I had to make the glass shape from my pipe form, clean it up, flox it in place, clean up. You know the routine, right?

Too close

Lop off the corner

Glassed and sealed

After making more pipe…. Really I had a long piece made with the pipe form and I’ve been cutting lengths off as I go. I only needed two long bits and I made several fittings from these.

Pic 1 shows I’m ready to fit the passenger or PAX outlet. You can see I don’t need the extra plastic on the valve. Pic 2 and I have ground it all off. Less weight added you might say. You can also see how well the valve closes one side completely.

Pic 3 and I’ve floxed it in place. Glass to this black plastic works really well.

Looks like excess material?

More weight reduction

Floxed in place

Here are pics of the system from the expanding duct which is fed by the floor NACA (not shown) to the trap door on/off box then the heat exchanger and then to the outlets.

You can see in Pic1 I’ve really tried hard to make the profile as thin as possible.

Does it all make sense now?

Top profile view

The system

Another view

A few more oil heat system pics.

Inlet pickup on the bottom

Outlet at the top

Side view

After ensuring the bottom slot was cut and clean I proceeded to flox and tape on the lower fitting as you see in Pic 2.

Pic 3 and this is my heat exchanger with Y valve at the top. This directs the warm air either forward, back or a mix of the positions.

Access slot cut

Glass and flox for the bottom

The basic unit revealed

With my Y valve firmly floxed to the top outlet piece you can see I get unrestricted airflow in Pic 1.

Pic 2 and the task of joining the top piece. Many of these jobs I did on the same day. I’m using West System with the fast cure for many of these parts and just afterwards I make a crude box in front of my gas heater and run it full blast – good thing its winter here! Parts are sufficiently cured in a couple of hours to work on the next thing.

Pic 3 shows the bottom outlet fitting ready to be floxed in place.

Full flow outlet

Glassing the outlet in place

Bottom fitting

Pic 1 is my plan for getting the air into the radiator box. I ended up going to a rubber and hose outlet with my half made parts in hand and I just bought a few big PVC pipes to see what might work.

I used the plastic pipes as a form or mold to produce my own inlet fittings. You see one of them in Pic 1 on the left. These end up being floxed to the main heater body as my ‘fittings’ The hoses fit together and make a seal yet are also easy to get apart. Perfect.

Pic 2 is where I have sealed up the ends in separate layups with Pic 3 giving an idea of how I’ve treated the ends. Its fun and fiddly work.

You might notice a nut and bolt too. I found two spots on the Heater that were perfect to drill through for fasteners.

Inlet plan

Sealing the ends

In-Out close up

By the way, before I joined the halves together I cut out exits for the inlet and outlets as you see here. Pics 1 and 2.

Pic 3 is the first stage of joining the halves.

Outlet slot

With radiator installed

The sealed unit

Cutting the Heater box open was done very slowly with a little exacto hobby saw. The same one I used to cut out the ailerons and rudders.

Once opened I cleaned out all the packers and fillers and removed the duct tape release medium. All was good as you can see.

Next up was to keep the heat in. I had some special reflective tapes that I had used in my cowls on JZE to protect the glass from exhaust pipe heat. It is proven and works and has an adhesive side to boot.

I laid this into both halves and then used some high temp RTV to seal all the gaps and as a joining medium.

Opened cover and cleaned

Heat reflective lining

Hi-temp RTV dams

Time for the lower or input duct for the oil heat to radiator section.

While the shape was more complex that the upper duct having done it once this was easier and more fun. Instead of micro I just used duct tape for the release as you see in pic 2.

Pic 3 and it’s out of the form and a very nice part. All good.

Formed duct shape

Glassed over the duct tape

Part cleaned and nice

Quite some work finally got the shut off box in place as you see it in pic 1. As it turns out it needed more modifications later but I was at least at a point where i could see it working.

Pic 2 shows roughly where it will sit.

Pic three and I have modified the Y valve to be a part of the outlet duct. I ground a lot of it away so it could sit easily. Some flox to hold it and I was still getting good weight reduction from this part. Or less weight added depending on your viewpoint.

This plane will be for flying at flight levels where it is cold. Heating is a safety matter.

Pic 3 also shows where things are going to fit. By raising the heat box/radiator my ‘wires’ will still fit underneath and it looks like the extended valve rod is going to work. I spent a couple of hours positioning that too.

Shut off box

Sitting in the corner spot

More layout testing