We had an AIRTRONICS D5, 24v, with an H-kit stamped on the data plate, installed in our boat with an 801 controller. This worked well because our heater pulls outside air into the boat, and room temperature modulation was controlled by the 801 integrated temp sensor. This was all fine and good, except that the 801's rubber buttons have aged and no longer work. I also desired the timer functions, so the EASYSTART TIMER seemed to tick all the feature and compatibility boxes. I got the EASYSTART TIMER, installed it, bridged the D5's GRRD + BNWH wires, and it works perfectly, reporting the D5's inlet air temperature sensor. All fine and dandy except our heater draws *outside air* into the boat and has no way of sensing the room temperature as the 801 so wonderfully did. I am a bit perplexed as to which model Eberspacher external room sensor I need and where to connect it: Is it one sensor lead to the bridged wires and the other to the solid gray wire on the D5 loom, OR to the EASYSTART TIMER's loom? I am unsure if this is even possible at all, as the literature does not show my configuration very well. Out of curiosity, I have tested connecting an NTC 10 kΩ thermistor to the D5's loom and also tested connecting it to EASYSTART TIMER's loom, both times I cold restarted everything, and in both cases the D5 didn't regulate off of the NTC thermistor. It may be I'm using the wrong thermister spec or this connection architecture simply isn't supported. Can you tell me which Eberspacher room sensor I need, and let me know how to connect it? Or, if what I am doing is a "Mission Impossible" case? For the love of Pete, why didn't Eberspacher include a room sensor in the EASYSTART TIMER as they did on the 801?

Question

We had an AIRTRONICS D5, 24v, with an H-kit stamped on the data plate, installed in our boat with an 801 controller. This worked well because our heater pulls outside air into the boat, and room temperature modulation was controlled by the 801 integrated temp sensor. This was all fine and good, except that the 801's rubber buttons have aged and no longer work. I also desired the timer functions, so the EASYSTART TIMER seemed to tick all the feature and compatibility boxes. I got the EASYSTART TIMER, installed it, bridged the D5's GRRD + BNWH wires, and it works perfectly, reporting the D5's inlet air temperature sensor. All fine and dandy except our heater draws *outside air* into the boat and has no way of sensing the room temperature as the 801 so wonderfully did. I am a bit perplexed as to which model Eberspacher external room sensor I need and where to connect it: Is it one sensor lead to the bridged wires and the other to the solid gray wire on the D5 loom, OR to the EASYSTART TIMER's loom? I am unsure if this is even possible at all, as the literature does not show my configuration very well. Out of curiosity, I have tested connecting an NTC 10 kΩ thermistor to the D5's loom and also tested connecting it to EASYSTART TIMER's loom, both times I cold restarted everything, and in both cases the D5 didn't regulate off of the NTC thermistor. It may be I'm using the wrong thermister spec or this connection architecture simply isn't supported. Can you tell me which Eberspacher room sensor I need, and let me know how to connect it? Or, if what I am doing is a "Mission Impossible" case? For the love of Pete, why didn't Eberspacher include a room sensor in the EASYSTART TIMER as they did on the 801?

This question is related to Eberspacher heater Easystart 7 day timer | 221000341500.

View product

Answers (3)

Answered by Butler Technik's David Butler
Posted 12th January, 2026 at 16:57 by David Butler

You require to install in addition an Easystart timer temperature sensor

https://www.butlertechnik.com/item/Eberspacher/Espar-Temperature-sensor-for-Easy-Start-Timer-Pro-and-Remoteand-221000342200/5XM

Yes, I agree, be so much easier if the integrated sensor in the timer unit could be used to modulate room temperature. Unfortunately not. In fact the large majority of Eberspacher controllers are designed out the box to work with the heater inlet air as the room temp reference - so remote temp sensors such as this are nearly always required for boat applications. The now discontinued 801 controller was the exception to the rule, having the very useful integrated temp sensor to utilise if required. Thanks

Posted 26th January, 2026 at 10:31 by Tony Gagliardo
With the EASYSTART TIMER and remote temp sensor, should I leave the GRRD + BNWH wires bridged and connect the temp sensor to the EASYSTART TIMER .....OR.... to the heater?
Posted 26th January, 2026 at 14:18 by David Butler

Hi Tony, please can you provide your Butler Technik order number for sensor? Thanks

Post a reply

Your name may be viewable as contributor - please leave blank if you wish to remain anonymous.

Please read our privacy policy for more information about how we protect your personal data.