Multiple timers for Webasto US market heaters


Yes you can have multiple timers on your US market Webasto Airtop 2000 st! Here's how:

WebastoTech USA (and Canada) is clueless about any of this, which is silly, because its really quite simple. First you need 3 parts. The Multicontrol itself (9030910D) , the Unibox/Multicontrol wiring harness (9031714A) , and the Unibox (9029784A). The unibox converts the digital signal to an analog one. The Multicontrol is what you want, as opposed the SmartControl. The difference between the two is that the SmartControl does not have the timer function.

The harness comes with a few ends which have plastic connectors, and one end that just has loose wires. The only wires you need from the loose ones are red (positive) and brown (ground). One hangup I had was getting the connector from the harness properly attached into the Unibox. There is a plastic clip which works like a gear to get the harness properly seated in its port on the Unibox. It is easy to only clip this in half way. It must be pressed in all the way in order to work. To get it all the way in, take the clip and rotate it so that it is 90 degrees all the way back, parallel with the top of the connector itself. Then press it into the port and rotate the clip upwards until it is perpendicular. Now the only other connector you need is the Blue black white and red plastic connector, which should have an obvious mate coming out of the heater unit. If you want the vent option, you also need to connect the pink wire coming out of the heater to the loose red/white wire on the harness. Now everything is connected.

You also need to change the settings to work with your heater. To do this, hold down the center button and the power button for 3 seconds. Then a menu will come up and you can select 2000 ST UB. Now everything should work!

Another thing to note is that even though the unibox changes the control of the heater unit, any change for fuel/O2 mixture you have made for altitude will still work. It took waking up in the middle of the night to call the UK to figure much of this out. I hope this will help others not have to do the same.



Hey jaross, nice build info,
As you know, you have to do all the compatibility work yourself. We needed a Tstat for our Thermotop C. Webaso offered the 7 day timer(useless and overpriced) or the Multicontrol, annoying interface and turns out not to work with the Thermotop.
After a lot of digging we found that the canal boat groups in the UK are using the Heatmiser Slimline N to control their Webasto units.
It works flawlessly as a Tstat for Thermotop with full features including frost setting(keeps cabin above 5C to prevent freezing.
I cannot confirm compatibility with Airtop.