servicing Trumatic E-3300 Furnace

[Mlw]

I know this forum is mostly looked at by Americans but there are also still Winnebago's in Europe.

I found out that Winnebago's for the European market were adjusted to European measuring standards so appliances came from the European market. So I have a Trumatic furnace instead of a Coleman, a Siemens Fridge instead of Dometic and a ENO stove instead of a magic chef.

I know the Trumatic E3300 well as I've found them aboard boats as well during my time at the Yacht broker.







These furnaces are famous for their extreme reliability during their very long lifespan. People only let them go because parts are not available anymore. Eventough the furnaces of Truma are still highly respected, they just aren't build as this beast and therefore will never meet the reliability or make the lifespan of these.


The furnace is actually one of the very few things the former idiot didn't touch and it looked like I'm the first to open it up since it's installed 42 years ago. Removing the cover of the furnace revealed a blanket of dust in certain parts, wile other areas probably still had the air of 1979 in there 
It really is saying something about the reliability of these furnaces.

I would have serviced it anyway as it certainly not the first time I see a furnace in a state like this. The problem however is that the Furnace shuts off within 10 seconds and the red error light lights up (Störung). This means the airflow is not sufficient anymore. It is actually the first one of all E-3300's I've encountered in my life that isn't working. 

There are 3 ways the Furnace will not work.

Shutting down within 10 seconds, Error light burning: Insufficient airflow.
Shutting down in about 50 Seconds, Error light burning: There is no gasflow or the battery is under 10.5 volts

You just gotta love the simplicity of the '70s 



A word of caution in advance if you do decide to service your heater yourself. As is is a late '70s build from Germany it is extremely over engineered and you will need a lot of patience finding all the bolts you need to remove just to take away the covers.



Next to that you need to treat the furnace very delicately as the wiring to the fanmotor is extremely thin and therefore extremely fragile.



Removing the top gets you to the fan immediately.



The plate covering the ventilation shaft and gaspipe is fastened with 7 screws you will find easily.

Then you need to remove the 3 bolts that hold the fan-motor.

Here it gets tricky, you will need to bend the wiring to the white resistor, or else you just can't remove the plate it is allready enough to give you a nervous breaksdown 


A Tip
if you can solder, see if you can shift the plastic coverings over the yellow and blue wire down and disconnect the wires from the resistor. This way you can prevent breaking the extremely thin wire to the fan motor like I did.



There are two things you need to pay attention to. The wiring and the airflowplate. This is just a thin tin plate that works the switch that controls the 10 sec. error mode. You see it hanging over the fanwheel in the picture underneath,




You still can't remove the fanwheel now, you first need to loosen the coverplate that's between the fanwheel for the aircompartment and the fanwheel for the outlet. You do this by loosen two tiny screws you see on the bottom just underneath the fanwheel.






After you removed the screws and the clamps holding the separation plate in place you can remove the whole shebang.

And here I went horribly wrong
I didn't pay attention to the markings, so I spend an hour to fix the unbalance again. So if you are going to do this, do pay attention to the markings. It will save you a lot of time, reassembling and disassembling and therefore breaking wires  W%

Now I unfortunately forgot to take pictures removing the seperation plate but it pretty much shows itself when you have the sepaeration plate holding the wheel and fan motor out. Do pay attention how the plate was assembled

Then you need to remove the screws holding the fanwheel to the fan-motor axle. You do this with an Alan key.


Before you loosen the screw note the marking on the bottom of the wheel. Place this marking on a spot that you later can use as reference to place the wheel back. Loosen the screw with an allan key and remove the wheel and axle by an upward movement and NOT by twisting. When you don't placed the wheel back on exactle the same spot you will get unbalance!!!

Better be safe then sorry so make a picture of the position of the axle thru the whole on the bottom and notice the marking on the wheel. again Put this marking on a point of reference before you loosen it. You really don't want your wheel touching after assembling or unbalance so you need disassembling everything again.




the blades of the fanwheel were completely caked with dust and sound insulation residue .

Remember?
The Heater you isolate with sound isolation so more heat comes out of the air hoses. You just stuff the space the heater is in until there is no room left, Only problem, the stuff doesn't like dry heat an disintegrate so all hot air hoses are now full with the stuff. Cleaning it up was also a real challenge cause as soon you touched the stuff it fell apart.

Thoroughly washing it with dishwashing liquid made it look again like this. Again, you just gotta love the '70s. It's 42 years old, gals and gents.





After this it was reassembling, resolder the wire I broke, and finding out I didn't go at it the right way, but hey "Everybody's gotta learn sometime".




Tomorrow we go further at it.

[Mlw]

After replacing the airwheel and testing the furnace out of it's covers it functioned fine.

I heard the gas valve open, the ignition was working and withing about 50 seconds it shut off as it should because I didn't connect the LG yet. 

Replaced the cover, Put the heater back in its place, reconnected the outlet and the LG line, and..... shutting off after 10 sec.      N:(

As I first tested it without the cover on and holding the sail "open",



Next I tried with the cover on but not screwed tight. the build in safety for the airflow was just touching the fanwheel when starting up and shutting down.




This part is known to be extremely fidgety once it starts malfunctioning (due to my own mistakes as I bend it removing the airflow wheel.

It is known that mechanics just short circuit the switch, but of course the safety is there for a reason.


So next procedure,  do short circuit the switch, see if it's working then and go from there.

More to come next week, as duty is calling again.

[AOBrodie]

At first glance, I thought it said "Traumatic".   D:oH!

[Mlw]

well....... (sound of crickets)

Maybe that's why they've changed their name from Trumatic to Truma 

[Oz]

"Still has the 1979 air in it"...

[yellowrecve]

Normal is the fan comes on, fan air flow closes the "sail" switch allowing electricity to open the gas valve and ignite the gas. The fan switch is bent to adjust and operate the switch it is attached to.

[Mlw]

Nothing to say against it

I worked in bars and nightclubs for decades and cleaned a lot of fan wheels in that time. the difference you can achieve by just cleaning is (literally) mindblowing.

I looked on the internet everywhere for a manual or tutorial, but alas, nothing. Going at it blindly you are bound to make mistakes.

I expect that the heater will work as soon as I short circuit the switch, as it did when the cover was off. Then it's re-adjusting the sail to the right specs again. It will be alright.

[Mlw]

I see that I still have to close off this topic.

After opening up the heater again i saw that the fansail was working AND... this time the heater worked as well 

I can't remember but maybe I closed off the gas valve for the heater or opened the one for the refrigerator.

But till now everytime I start the heater up it lights thus so far, Problem Solved.

[Oz]

Well, you did a lot of servicing on it, so that's done.  As for the actual fix... yeah, it happens a lot to may have been something simple that we didn't even think of.