Sierra Nevada Airstreams

What to do when the furnace screeches?

Here's what we found when the B-Van furnace motor bearings decided that they had had enough.

The first job was to remove the four bolts holding down the couch. You can see the holes in the board on the left side of this picture. The heater duct to the bathroom runs beside the generator box, through a bulkhead, beside the wheel well and on to the rear. The transfer switch for the generator is on the forward side of the bulkhead near the center of the picture. The converter is at the left bottom of this picture. The seat belt is draped over the generator box.

Dropping nuts and washers was a problem so we replaced them with nuts that dug into the wood. Then we had to push them out and reset them when we re-installed the couch in order to get them in the right places.

Here's what the generator transfer switch looks like. There is a relay for each side of the power line.

We found that the 2x2 mounting boards for the couch had separated from its mounting. The walls of this box are something like 15/32” ply with the woodgrained finish. The 2x2's had been stapled to it. Now they are screwed in place. That firmed up the couch quite a bit.

The main reason to remove the couch for this episode was not the furnace. The previous owners had put a safe in the cabinet under the couch and that was being removed. As always, a few other things were discovered along the way. The big one was that the heater duct to the bathroom had been disconnected. That's not good for furnace air flow.

The bolts through the floor that held the safe were sealed with some goop to make sure exhaust gases could not enter through them.

As you can see in the top picture, there are wires running all over the place. some to the transfer switch, some to the converter, some to switches elsewhere in the rig, and who knows what went where. You'd think documentation would be something worth doing. The guys that made the transfer switch provide the example of how it should be done. Why couldn't Airstream follow their example?

The furnace can be pulled out by removing the screws holding it to its facing from the front. The exhaust and fresh burner air ports are simple slide togethers. You can see the ducting that is mounted to the side of the van for them between the bucket and furnace.

The bucket was to keep track of all the parts. You can see the main blower at the top of the pile in the bucket. The blower had been in that hole in the furnace you can see at the top center of this picture.

You can also see the duct port near the front of the furnace had been blocked off. This is where the duct to the bathroom was supposed to be attached. It had been disconnected and blocked to allow other stuff under the couch

The controller board is mounted to its cover which was opened to remove the burner motor wires. You can see the holes for the screws that hold the furnace to the facing on the flange.

The blower motor had two wires running to the front to be unplugged. After several sheet metal screws holding shrouds in place were removed, it could be pulled from the furnace with its two blowers, one for heater air and the other for burner air. Each blower had its own sized allen setscrew to hold it to the motor shaft. Hydroflame - Atwood rv furnace parts provided a new motor for $90 plus $10 S&H or so.

Since we didn't tackle the motor until right before a rally, we put some ATF in the bearings of the old motor to lubricate them. That lasted two of the three rally nights.

When Dave re-installed the blowers on the motor, he made sure they were straight. The burner air fan is an impeller type and easily bent. After bolting in the motor, clearances were checked to make the blowers didn't scrape on anything.

You can see the propane fitting near the middle of the furnace going out to the left. Make sure you have the propane turned off before disconnecting the line! After reconnection, turn on the propane and use soapy water to check for leaks.

Here is some of the wiring above the converter, include some relays behind the transfer switch. You'd think someone would provide some documentation or wiring diagram.

The furnace had two extra ground wires. One was a short stub. The other went all over the place before it ran into the converter. Now why was that?

At least now we can get a warm and quiet night's sleep – at least until the battery doesn't go dead and the propane lasts.

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