Espar / Eberspaecher D2 Heater Installation in a Sprinter

After many cold nights without a heat source in our Sprinter, we finally bought and installed an Eberspaecher Airtronic D2 heater. We chose to do the installation ourselves, and while time-consuming (probably 10 hours of labor), it is definitely a doable project and we recommend doing it yourself.

We bought our heater at Heatso, based in the UK. They’ve been very responsive, and shipping from the UK took only one day! They’re knowledgeable and can give great advice and information. We’ve found them to be the cheapest distributor online, so check them out. Full disclosure: They also helped us out with a discount on our heater.

In this blog post we’ll lay out how to install the Airtronic D2. Our kit included the heater with installation kit, floor mounting bracket, EasyStart Select controller, remote temperature sensor and high altitude sensor. The temperature and altitude sensors are optional, so if you don’t need them, you can save yourself some of the wiring.

Installation kit

Installation kit

We’ve found a few sources to be helpful in the installation process, as the instruction manual that comes with the heater is lacking in some respects. Here are the key references we used:

Tools required:

  • Screwdrivers
  • Ratchet with metric sockets
  • Drill / drill bits
  • Hole saw (1-⅛ or 1-¼ inch diameter)
  • Crimping tool

Things to buy:

  • 12” of 5/16” ID fuel line (auto parts store)
  • ¼” male-to-male barbed fitting (hardware store / Amazon)
  • Splice connector (Amazon)
  • Cable staples to route wiring (Amazon)
  • Primer
  • Muffler putty (Amazon)

Installation process

The basic steps to the installation are: 1) installing the heater in its physical location; 2) routing the fuel lines and installing the fuel pump; 3) routing the electrical connections. Easy enough!

First, you need to find the best location to install the heater. You’ll roughly need a space that is 7 x 18 inches in footprint. Ideally you would want a location that is close to the van floor, minimizes duct length for the heat output, and most importantly, where the van floor is not obstructed from cross members or the vehicle frame. Many people install the heater under the passenger seat in the Sprinter, but we already had our auxiliary battery system in that place and weren’t going to change that. The second best option in our view was to install it on the passenger side between the sliding door step and the rear wheel well. Given our bed frame construction, it left us with the ideal space to fit the heater without much modification of our setup. We removed one small wooden crossbeam from our bed frame for easy access to the space. The only downside to this location was that our wiring harness to connect to the battery wasn’t long enough – more on the solution to this further below.

1) Install heater

With the location identified, you need to drill 3 holes into the van floor: 2 holes are 1-⅛ inch diameter for the intake and exhaust hoses, 1 smaller hole for the fuel line (diameter depends on your exact setup). The holes are a total of about 3 inches apart. So with the location identified, get under the Sprinter and check the underbody of the van. In our case, when mounting the heater behind the sliding door step, going from front to rear of the van, you’ll find: a cross member (6 inches), then 6 inches of unobstructed van floor, and another cross member right in front of the rear wheel well. The goal is to put the holes right in the center of the 6” unobstructed van floor.

Back at the top of the van, mark a line on the floor that is 6 inches behind the sliding door step – that’s where the crossmember ends. In our case, our wooden van floor overlaps the rear of the sliding door step by about 1 inch, so be careful to account for that. Double check everything to make sure you get it right. Next, mark on the floor the center of where you’d plan to put the first 1-⅛ hole and make sure it is at least ½ inch behind the crossmember line you just drew. Take a small drill bit and drill a hole through your floor, then check under the van to see if you did it right. If not, the hole will help you adjust and will probably be cut out of the floor later on (unless you were way off).

With the first hole location verified, now mark where the 2 other holes need to go. If you’d like to make sure, drill another pilot hole at the center of the second 1-⅛ inch hole.

Use a hole saw to drill 2 holes through the floor at the exact location where you pre-drilled your pilot holes. The sheet metal is thin and it shouldn’t take much to get through it. Finally drill the remaining hole for the fuel line.

When installing the heater, we chose to have it 2.5 inches off the van floor because it fit better into the space (part of our bed frame was in the way. If you’d like to install the heater as close to the floor as possible (which is a good idea), you should now proceed to cut a hole into the wood floor (not the sheet metal) to accommodate the mounting bracket. You can find good documentation from Traipsing About. In our case, we built a small enclosure from 1x3s that raised the mounting bracket off the floor.

With the holes drilled and the mounting bracket location prepared, remove any burrs from the sheet metal and apply primer. Once the primer is dried, We applied exhaust repair paste to all exposed areas that will be in close contact with the hot exhaust pipe. You can also get heat resistant stove pipe sealer at your hardware store.

Get the heater, the mounting bracket, 4 nuts and washers, the transparent fuel line, 3.5mm rubber hose (the thinnest from the installation kit), 2x 9mm clamps, the exhaust and air intake hoses and 2 clamps. Place the mounting bracket on the heater and mount it down using nuts and washers. Stick the fuel line into the rubber hose and make sure it is inserted far enough to butt up against the fuel intake line on the heater. We’ve found that heating up the rubber and using WD-40 helps. Attach the rubber hose to the fuel intake and attach the 2 clamps. Then attach the air intake and exhaust with clamps (make sure you get the order right, there are small arrows on the intake and exhaust that show direction of flow). Now route everything through the holes in the van floor and place the heater in its spot. Mount down the bracket to the floor to secure it.

We found a spot under the van floor to easily mount the muffler. Cut the muffler pipe to the appropriate length, drill a hole for the muffler mounting bracket, attach all using clamps, and route the remainder of the exhaust pipe to point away from the van.

2) Prepare the fuel pump system

The NCV3 Sprinter (2008+ model years) comes with an auxiliary fuel tap from the factory, which makes this job a lot easier.

To prepare all the fuel lines, we went with the advice from Traipsing About and  narrowed down the fuel intake from a 5/16” rubber hose, to a ¼” barbed male-to-male fitting, to a 5mm rubber connector, to the black fuel line. You need to clamp all the connections. Use a 14mm clamp on the 5/16” hose, and an 11mm clamp on the 5mm hose. It took quite some time to get the 5mm hose on the ¼” fitting. Apply heat and some WD-40 to make it a bit easier.

With the fuel lines prepared, it’s time to move under the van floor. Identify a good mounting location for the fuel pump (and note that it has to slope upward at a 15-30 degree angle). If you need to drill a hole, make sure to apply primer. Then mount the fuel pump in place.

Now lay out the routing of the fuel line. Try to make the rise of the transparent fuel line from the fuel pump up to the heater as gradual as possible, attach the fuel line using zip ties, then cut it (with a blade) so that it butts up against the upper end of the fuel pump. Attach a 3.5mm rubber hose with 2x 9mm clamps and then join the fuel pump and transparent fuel line.

Next, lay out the black fuel line (as prepared above) from the Sprinter fuel tap to the fuel hose. When adjusting the length of this hose, try to shorten the wider part first. In our case, we kept about 5-6 inches of the 5/16” hose. Clamp the 5/16” hose to the fuel tap using a 14mm clamp. Then route the fuel line towards the bottom end of the fuel pump, cut it (with a blade) so that it butts up against the fuel intake. Then attach the 5mm rubber connector and 2x 11mm clamps, and clamp everything in place.

Pay attention that all the connections butt up against each other, to prevent air bubbles in the fuel line.

3) Connect the wiring harness

Now for the most confusing part. The installation kit comes with a multi-purpose wiring harness (that can be used with different heater models), so you will not need all the wires. The wiring harness starts with the heater connector plug, and has 3 strands that go to the controller, battery, and fuel pump. Identify the mounting location for your controller. In our case, we installed it next to our light switches on the driver side of the vehicle.

We ended up routing all our wires to the driver side of the vehicle. The battery wire was not long enough to reach our fuse box or the battery, but we did have existing unused wiring in place at our light switches. So our battery cable and controller cable went to the storage compartment where our light switches are attached. The fuel pump wire we routed along the driver side wall to the front of the van.

Battery wiring

The battery cable comes with 4 wires. 2 thick (10-12 gauge) wires – one red and one brown, 2 thin (16-18 gauge) wires – one red and one red/white. Insulate off the red/white wire with electrical tape, you won’t need it. The brown wire goes directly to your negative battery terminal. The 2 red wires should run through fuses (individually) before they connect to the positive battery terminal. You could either do this through an existing fuse box, or use the 3-fuse box from the installation kit. The fuse box will need a 20A (thick red wire) and a 5A (thin red wire) fuse in a 12V system. Don’t insert the fuses just yet, this should be the final step of the installation.

Battery cable wiring

Battery cable wiring

Fuel pump wiring

The fuel pump wire needs to be routed to the fuel pump (obviously). It has 2 wires – green/red and brown. We opted to route as much of it through the interior of the van, although that’s not necessarily the only way to do it. Because we didn’t want to drill any additional holes into the van floor, we started searching for preexisting openings close to the fuel tank. The best one we could find sits in the cable channel between driver and passenger seat. To get to it, remove the passenger side floor mat, and then unscrew the black covering that sits on top of the cable channel. You’ll find it a few inches right of the driver seat box, covered by some tape.

Route the fuel pump cable to this spot, then add one of the grommets from the installation kit, and put the cable through the floor. Then go along the fuel tank (behind the rock guard) and zip tie the cable along the way. You can cut it to the appropriate length at the fuel tank.

To finish connecting to the fuel pump, strip the wire, then crimp it to the connector that will insert into the fuel pump plug. There are several similar connectors in the installation kit, make sure you take one for a thin gauge wire that will fit into the plug. Once crimped, insert the 2 wires into the plug (either way is fine), then insert the plug into the fuel pump. Now you’re done crawling under the van.

Controller / Remote temperature sensor / high altitude sensor

The most complicated part of wiring is the controller end. The harness has 10 wires of which you’ll need 7: red, brown, yellow, blue/white, grey, grey/red, brown/white. Isolate the others with electrical tape (blue, black, red/white).

The remote temperature sensor has a brown and a grey wire. Use the 2-wire plug from the kit to connect the brown to brown/white, and grey to grey. In addition, you will have to splice the brown/white wire with the grey/red. I bought a simple plastic splice connector for the job, it makes the job very simple. If you do not have this sensor, you need to simply connect the brown/white with the grey/red wire.

The high altitude kit comes with a harness that sits between the harness and the controller. Crimp the wires from the wiring harness to the pre-existing connector of the high altitude sensor (you just match the colors: red – red, brown – brown, yellow – yellow, blue/white – blue/white). If you do not have a high altitude kit, connect the wiring harness to the controller directly.

The controller has 4 wires: red, brown, blue/white, grey/black. You will not need grey/black, it is used to connect to the ignition system (you want the heater to work without the ignition being on). So using the plug from the kit, connect red – red, brown – brown, blue/white – blue/white. Note that this only applies to the EasyStart Select controller. If you have a different one, check the wiring diagram for your model.

Start it up

With all wires connected, the fuel pump installed and the heater in place, it’s time to start the heater up. This is a bit nerve-racking after all this work. Plug in the 20A and 5A fuses (be careful not to switch them). You should see the letters ‘ini’ on the controller screen. The heater should start running, slowly, with cold air. After about 60 seconds, you should be able to hear a clicking noise from the fuel pump. On the clear fuel line you will be able to see some air bubbles progress towards the heater. Given that initially there is only air in the fuel line, it will take a bit of time for diesel to reach the heater. For us, the heater shut down after 2 cycles of fuel pump clicking. We pulled the fuses and reinserted them to restart the heater, and the whole process starts over. On the second fuel pump cycle of the second attempt, the fan sped up, we started to hear some exhaust noise, and warm air started flowing. Success! If it doesn’t start up, try for a 3rd or 4th time, check the controller screen for information, check the fuel line for air in the hoses, and check the manual. Luckily we got it right on the first try.

Once running, test the remote temperature sensor by heating it up (e.g. breathing on it). The controller should show the adjusted temperature within 30 seconds or so, and the heater should adjust its fan speed.

And that’s it! The heater makes a world of a difference, especially on ski trips. It easily keeps the van at 70 degrees, even if it’s 20 degrees outside. There’s also no condensation in the van in the mornings. We can leave Leika in the van for a few hours in freezing conditions without having to worry about her. So while we were skeptical of making the investment (and we didn’t have a heater going to South America), we’re pretty happy about the new-found comfort.

Heater in a box

Heater in a box

Posted in Van Build, Van Information and tagged , .


  1. you guys are my hero’s!!!! hahaha I am about to embark on installing mine and wouldn’t you know you guys brought this up in the nick of time!!! This makes it look much less intimidating but I am still not sure if I will try it myself of go with a pro install… I have a 2015 144 and I know it should be easy but something about wires just gives me the hibbe jebbies hahaha anyway if I do end up doing it myself I will be all over your blog thanks again for being awesome and keeping the van life going!!! such an awesome community!!!

    -Perry Driver of “The Bumble Bee”

  2. Another quick thing I just thought of is that my kit did not come with a mounting bracket like the one that you guys have… I am ok with just mounting it directly to the floor if that is ok but I just want to make sure that the heater will function properly that way… any advice??

    • Perry,

      Thanks for the nice comment, we always like hearing that our articles are helpful. On the mounting bracket, I would say you should be able to mount it directly to the floor. The heater has 4 threaded rods on the bottom that we used to attach to our metal mounting bracket, which you can probably attach directly the van floor. Alternatively, you can just make up a simple mounting “bracket” by using 2 pieces of 1″ wide steel (from a hardware store) that run lengthwise along the heater. You just need to drill 2 holes in each of the steel pieces to attach to the heater, and then screw the contraption to the van floor. Just make sure that none of the materials close to the exhaust are flammable. Hope this helps!


  3. So I ended up having someone install mine cause I figured it would be an easy way to get heat fast and that was a huge mistake!!!! They messed a bunch of things up and I spent just as much time fixing their mistakes as I would have done installing it… I think I’ve got it worked out now but I do have one question mine did not come with a temperature controller it only has the display controller like the one you guys have pictured my heater only has one speed and one heat… HOT lol do you guys know where I could buy just that sensor?? And also could in the picture you have of the controller and the sensor mounted which one of those is the sensor?? Thanks again for your help guys!!! I should have just done it myself lesson learned!!!!

    • Perry,

      Part of the realization of working on our van was that we’ve become very skeptical about ‘experts.’ Without doubt there are people who really know this stuff, but we’re not counting on finding them on Yelp. That’s why our tendency has been to do things ourselves, with the added benefit of saving some money.

      In the picture you mentioned, you can see (from left to right): the temperature sensor, light switches, USB outlets, 12V outlets, heater controller.

      Now as for the temperature sensor, the heater should still regulate itself without an external temperature sensor. As far as I read, it measures the temperature of the air coming into the heat exchanger (the back of the heater) and uses that to regulate fan speed. The benefit of the external temperature sensor is that you can place it where you want. In our case, the external sensor is helpful because our air comes into the heater from our storage compartment under the bed (which isn’t heated), and we want the heater regulated based on the living area temperature. If you have hot air coming into the heater and it still runs at full speed, it might be worth calling Eberspaecher support about it.

      For the temperature sensor, I would just check the Eberspaecher distributors (e.g. online or ThermoKing if you have one nearby). I’ve also read that you could make your own sensor if you want to save some money, some info here and here.


  4. Bonjour et merci. tout est bien sur votre dessin de branchement du contrôleur mais ce dessin est tellement petit que nous n’arrivons pas à lire les couleurs;
    Contrôleur : rouge / brun / bleu-blanc/ gris-noir

    Faisceau : rouge / jaune / gris / blanc-rouge / brun / bleu-blanc / gris-rouge / brun-blanc / bleu / lilas
    quel fil se raccorde a quel fil ?
    Cordialement jean Marc de Toulon France

    • Bonjour Jean Marc,

      Si vous n’avez que le controleur et faisceau (pas de capteur de temperature ou capteur d’altitude), c’est simple: Il faut raccorder rouge a rouge, brun a brun, et bleu-blanc a bleu-blanc. Le gris-noir est seulement pour raccorder a l’ignition. On n’a pas besoin d’autre fil, vous pouvez les isoler.

      Excusez-moi pour mon mauvais français!


  5. Thanks again Jakob!! You guys are what I would call the experts!!!!!! I have definitely learned that it’s worth doing myself every time now… Lol as far as the temp sensor is concerned I think I’m OK now hahaha I’m lying in my van right now in the mountains in Oregon it’s about 25 degrees outside and I’m nice and cozy!!! Not too hot not too cold my controller still reads the same temp and then flashes to a set of lines which is supposed to be the internal temperature I do not have the grey wire connected which according to a Manual that I found is supposed to default to the internal sensor. So for now I think I will leave it and maybe order than sensor from heatso at a later date. Once again thank you so much for all your help I will definitely be sending any friends and fellow DIY sprinter conversion guys your way if they plan on doing a heater!!!


  6. Fantastic post, Jakob! I have the exact same equipment as you. Did you need to disconnect the D2 internal temp sensor, or does the remote temp sensor automatically override it?

    Also, in contrast to the EasyStart Select manual, my EasyStart Select does NOT allow me to program a set run time duration. Does yours?

    Thank you!!

    • Mark,

      Thanks for the kind words, I’m glad people find the post helpful. The external temp sensor is recognized automatically, you don’t need to change anything. It’s easy to check whether the sensor works properly – just change the temperature around the sensor (for example by breathing on it) and see if the heater changes speeds. Our EasyStart Select also isn’t programmable, it only has on / off and selecting a temperature. Given the fuel efficiency and the fact that the heater can run continuously, we didn’t think we’d ever need a timer.


  7. Hey Jakob, I just wanted to say thanks for your detailed write-up! I’ve been struggling to find a reliable/intelligible source for the wiring of my heater/controller along with the temp sensor. Some of the Eberspacher literature seems to have contradicting info and/or fails to mention certain wires or connections that need to be made. Anyways, your site prevented me from pulling out the little of my hair that remains. Thanks!

  8. Very nice write up. I’ll be ordering my eberspacher heater soon from Heatso as well. How is the noise with the unit mounted inside the vehicle? Can you sleep comfortably with it running? Mine will be mounted in a small shuttle bus rather than a sprinter, so I have room to mount it in a box underneath the bus if necessary, but I would prefer to mount it inside.

    • Dan, the noise on the inside is really not bad, it’s quieter than our ceiling fan. On the outside you can definitely hear the exhaust, so I would recommend getting the muffler – makes a big difference!

  9. Thank you! I totally owe you a beer, or tea, or coffee!

    I’m in the process of working through the wiring on my Espar (underseat installation), and got to the gray/black wire on the EasyStart controller. I had no idea what to do with the gray/black wire till I saw your post. You just saved me lots of WTF head-scratching moments.

    Your tip about running the pump wire through the chase between the seats. Saw the hole, didn’t think anything of it till I re-read your post. Thanks again for that as well.

  10. Hi
    Love your posts. Looking to purchase an espar D2 from Heatso. Curious about taxes and duty to the US. Do you happen to remember what they were?
    Thanks so much.

    • Hey Ted,

      I believe it was about $30, but best to shoot Heatso an email as I think they ship to the US regularly. Shipping was with Fedex and we actually got the heater within 2 days, faster than I would have expected shipping from within the US!


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