Part: Espar Airtronic D4S Superseded by M2 D4R

For our coach air heater, we have an unusual Westfalia specific Espar D4S and not a regular Espar D4.

From Wasaabi and others, we know we have a Westfalia specific circuit board in the heater which can communicate with the windshield central computer console. From OneManVan, we know that not all Espar controllers are compatible with our heater.

The "S" version of the D4 allows for longer and narrower ductwork.

Released in 2019, Espar has replaced the D4S and D4 Plus models with a new M2 D4R (recreational model) (the standard D4 model has also been superseded by M2 D4L???).

https://www.heatso.com/espar-eberspacher-airtronic-d4r-recreational-12v-4kw-heater-kit/?aff=6

The nomenclature is a bit unclear with a "M2" label in the model name which would seem to suggest a marine application.

From the description of the new heater, the service life is now 5,000 hours versus the previous 3,000 hours. Noise level is also reduced. High altitude adjustment is automatic.

Note: There may be some good sales on the superseded D4S model. One might use our original Westfalia circuit board in a replacement D4S if the circuit board is good.

There is also a replacement for the smaller D2 Airtonic model, the S2 D2L model. Don't know of any Westy owners who have replaced their original heater with a smaller heater.

https://sprinter-source.com/forum/showthread.php?t=75153

Good news to see Espar improving their line, and good for Westy owners looking for a replacement and upgrade (especially now with built-in altitude kit). Checking out the site I see they also have a new line of “EasyStart” controllers/timers. Search for “easystart” to see various models. The simple thermostat and timer seem backwards compatible (although not with the D4S and Westfalia-specific ECU, which can be replaced). An interesting option is the radio remote which allows control of the heater from 1000 meters away.

Actually the simple EasyStart control and timer, I suspect, is backwards compatible with the D4S even using the proprietary Westfalia ECU so long as you don’t expect the diagnostic function to work. Not sure of this, but it’s likely due to the fact that our Westy D4S’s can also be controlled by a regular electronic thermostat (as discovered by PNWsquid). Good to have backup options in case of trouble with the Westy main controller by the windshield.

Wasaabi said:

Actually the simple EasyStart control and timer, I suspect, is backwards compatible with the D4S even using the proprietary Westfalia ECU so long as you don’t expect the diagnostic function to work. Not sure of this, but it’s likely due to the fact that our Westy D4S’s can also be controlled by a regular electronic thermostat (as discovered by PNWsquid). Good to have backup options in case of trouble with the Westy main controller by the windshield.

Click to expand...

I doubt any Espar controller is - or ever will be - compatible with our Westfalia specific D4S ECU. It's a custom ECU designed to only work with our Westfalia Central Electronic Control panel.

For example: I purchased a Digi-Max D1000 and connected it to my OEM Westfalia D4S. It did turn the heater on - but it never turned it off - regardless of how low I set the desired temperature!

Espar basically uses three wires to control the heater. The Yellow wire is call for heat. When 12vdc is applied to this wire a relay inside the heater is energized which powers up the ECU. The other two wires are basically desired & actual temperature. I compared the voltages on these wires. The Espar Digi-Max controller and Westfalia Central Electronic controller output very different voltages. Their method of control is different - IE: incompatible!

Any basic thermostat can be used to control any Espar heater. Simply apply 12vdc to the Yellow wire ( call for heat ). The other two wires going to the heater - IE: desired and actual temperature are left disconnected.

However - beware the heater will run at a fixed power output level. IE: it won't adjust the blower motor speed or dosing pump pulse frequency. Some consider this an advantage as it helps eliminate the problem of soot build up when running at the lowest power level.

Thank you for correcting that, it’s been some time since I had to dig into the Espar. I do have a replacement non-Westy ECU in my D4S along with the D-1000. This controller does very wide temp swings which is a bit uncomfortable but is supposedly to reduce build up. Regardless, I like to blast the heater for a minute or two before shutting off in hopes of burning off whatever has accumulated.

As a side note, my D-1000 recently displayed the “maintenance required” reminder. The default for the reminder, which I never changed, is at 1000 hours. The strange thing is I doubt I’ve used it anywhere near 1000 hours. I’m not sure if this “clock” is stored in the ECU or the D-1000, but I’m going to check if there is a way to get current runtime so I can track it for a while and check if it’s correct. If anyone knows off-hand let me know.

Manuals, including info for the M2 D4R which replaces the D4S.

https://www.butlertechnik.com/technical_library/m2-d4l-airtronic-d118

Heatso.com blog post:

https://www.heatso.com/blog/upgraded-espar-eberspacher-airtronic-units-arrived/

[Selected portions of blog post.]

The new Espar Airtronic S2 (D2L) and M2 (D4L) autonomous heaters: A review


Ten years after their release, Eberspacher / Espar Airtronic D2 and D4 have finally received an update. Named Airtronic S2 (D2L) and M2 (D4L), the two new heaters pack state-of-the-art technology in the same footprint, while significantly reducing fuel and electricity consumption. However, can they be called worthy successors to the last-decade’s heaters of choice? Let us find out.

. . .

Here is a quick summary of the improvements in Airtronic S2 (D2L) and M2 (D4L):

- Same case, easier installation

- Much quieter pump

- Integrated altitude kit (up to 3,000 m -

- Life span doubled to 5,000 hours

- Stepless control of heating performance: from 850W to 2,200W (From 2900BTU to 7500BTU) for the S2 and from 900W to 4,000W for the M2 (from 3070BTU to 13650BTU)

- More environmentally friendly

- Starts at up to -46° C

- New and more intuitive Easystart Pro control

- CAN bus protocol with simpler error codes

Conclusion

It is time to return to our initial question: can Eberspächer Airtronic S2 and M2 be called worthy successors to Aitronic D2 and D4? In our eyes, absolutely. While not exactly revolutionary, they manage to improve on almost all of the important areas, providing a natural continuation to a respectable line of products. If you are looking for a quiet, reliable, and convenient air heater, Airtronic S2 and M2 should prove an enticing choice for protecting yourself from the elements.

[END]

Heatso.com price is $1598, including the Pro Timer control, fuel pump, wiring harness, etc. Shipping additional.

https://www.heatso.com/espar-eberspacher-airtronic-d4r-recreational-12v-4kw-heater-kit/?aff=6