This is the first thread of a series of threads that I plan to post that explore the furnaces in Trillium
trailers. I plan to dissect the furnaces for both the 1300 and the 4500 trailers. Unfortunately, I don't have any examples of the earlier furnaces, so I will concentrate on the later, models.
This thread is actually about something most will never have seen before, but I think is way cool, the optional 9-3608 blower assembly. This unit adds some fan powered air flow to the gravity flow. It is ironic that I go on and on about how I love the Trillium
furnaces because they are practically silent, and don't require any electrical
power, and now I have a blower for one.
I powered it up. It is still quite quiet, and it moves a respectable amount of air.
I looked at the three furnaces that I have in Calgary, they all have mounting holes on the back of the furnace
for this unit. Two are near the top of the furnace
, above the gas valve, and one just above the gas valve. The design is a bit strange. It sucks hot air from the top of the heat exchanger and blows it out the front. I would have designed it to blow cold air across the heat exchanger, but what do I know. This unit can be powered by either 110VAC, or 12 VDC. I understand that there is another version that only has a 12 VDC power supply. This unit has its own converter built in.
The first picture is the back of the termination cover. It has a circuit diagram. This diagram is not quite complete. There is a push button that is not shown. It shorts across the fan control. Sort of a manual override. The switch selects between 12 VDC, Off, and 120 VAC. The transformer has black and white primary wires, and red and blue secondaries. Judging from the circuit diagram, the secondary winding is set up like an Edison 3 wire circuit. The middle of the winding is the negative, (neutral, sort of) with the blue wire. The ends of the winding act as two separate, and inverted from each other, hots. The diodes give an output that would look just like a full wave bridge. The selector switch is used to switch the negative. Not a good practice. It either routs the negative flow back to the transformer, or the negative terminal on the 12 VDC connection. I am sure that there is some obvious reason for the diode on the selector switch, but I don't know what it is. I would think a jumper would work as well