Sprinter van: Diesel heater installation

Hoo boy, this was a project. 

Second to designing, sourcing, and installing our van's entire electrical system, installing a diesel heater takes second place as the most involved project of our build. After a few weeks of work and crossing fingers the heater would fire up, I'm stoked to say we officially have heat in our van! It's at least as big a day as the one when I tested our electrical system and, by golly, it worked.

This post will be pretty detailed (read: long) with the intent of saving someone time that I spent going down rabbit holes, worrying about and researching some facet of the design, and redoing things. It'll be both specific to our T1N Sprinter (2006, so 2001-2006 Sprinter years) and general to diesel heater installations. I'll do my best to outline the considerations, the steps, and the details. 

Starting with our considerations:

• Our 2006 Sprinter does not include an auxiliary fuel line so we had to drop the fuel tank and drill into the fuel sending unit to install a standpipe before running the line from the tank to the heater
• We opted to put our heater (like most) inside the passenger seat pedestal which, in a 2006 Sprinter, only leaves a small (but workable!) space to install it
• We just couldn't justify the 10x price difference between a reputable brand diesel heater (Espar, Webasto) and a CDH (short for "Chinese Diesel Heater") so we sourced a cheap Chinese heater
• We did swap out some key parts in the Chinese kit, namely the fuel line and hose connectors, exhaust pipe, fuel standpipe, and fuel filter (we had justifiable reasons and more on these details later)
• We wanted our thermostat/controller to be located mid-van/driver's side where the rest of our electronics are and at about chest height so it would read the temperature where we'd be feeling it

I think that about covers our considerations. Now, to get them out of the way, I'll go into mistakes we made and what we did to solve for them.

1. Originally, I used the metal plate that comes with the heater and is used to mount it as a template to drill through the van's floor (even sourcing a specific hole saw down to 1/8" accuracy)… Only to realize the exhaust pipe will get hot and with it basically touching the van floor and almost 20 years of grime on the undercarriage of our van, I then cut a large rectangular hole into the floor
2. When I originally ran all the wiring for our electrical system, I didn't think to check the amperage a diesel heater draws when it fires up (to warm the glow plug), which is around 8-10 amps, so I had run 16-gauge wire for about a 40' run to/from the fuse box above the rear driver's side wheel well… Way too small of a gauge. I went back and strung a 10-gauge positive lead from our fuse box to the heater and a short 10-gauge negative/ground lead to the factory grounding point under the driver's seat (because our fuse box is grounded to a negative bus that is in turn grounded to the vehicle chassis, the grounding loop is complete)

Those two mistakes cost significant time, I'm not gonna lie. If I had discovered the too-small-of-gauge wiring while I was running 20-gauge, 3-conductor wire for the controller from the heater back to above our counter (which is close to our fuse box), I could have saved a decent amount of time and effort. Oh well, these are the joys of figuring everything out as we go. Even after spending dozens and dozens (and dozens) of hours researching before we began and while we were doing the project.

For the sourcing specifics, we went with these items. This is detailed but not exhaustive. This is a massive project that required lots of odds and ends in the tool and accessories departments.

• HEATER: 2kW CDH from Amazon

The brand is irrelevant. These are all made in the same factory and come with the same kit of parts. The size (in kilowatts) is not – it's very important. These heaters come in 2, 5, and 8kW versions. Our Sprinter is a 140" Super High Ceiling with a decent amount of insulation. From the vast amount of information I read, 2kW is all we'll need to stay plenty toasty down to 20 degrees or less. Getting a larger/higher-output heater would likely cause issues of soot buildup and poor burning because it wouldn't need to burn as hot to keep our van comfortable.

Once the kit arrived, like I mentioned we swapped out a bunch of things for Chinese knockoff Espar parts. Afterall, the CDH design is a knockoff of the now-expired Espar patent.

•  FUEL LINE, FILTER & HOSE CONNECTORS: Espar knockoff from Amazon

Everything I read unanimously mentioned ditching the green fuel line that CDHs include and getting a clear, stiffer line. The Espar knockoff also has a smaller diameter which is important for conserving fuel and delivering the proper amount of fuel to the unit. The hoses are sized differently for different sized heaters (i.e. the 2kW and 5kW models I've read are identical, but the 8kW models use a larger diameter hose). The inner diameter of the fuel line is 3mm. This is important when matching up replacement parts! That kit also included a slightly beefier filter which we appreciated, so we didn't use the cheesy filter included with the CDH. Also, this kit included rubber hose connectors and matching fuel line clamps. MUCH better than the cheap clips the CDH kit comes with (and it doesn't include rubber hose connectors). Every installation I looked at seemed to use the rubber hoses to connect to the clear fuel line. Every single one, and the internets never lie.

• EXHAUST PIPE: 1-meter Espar knockoff from Amazon

The main reason I "upgraded" the exhaust pipe is because the CDH pipe didn't allow for a section to come after the muffler. I didn't want the muffler to be the final piece of the exhaust system sticking out from under the van and a lot of installs I saw used the Espar pipe. To be safe, I ordered the 1-meter length (vs. 24") although I only used about… 24". It was only a few bucks more.

• FUEL TANK STANDPIPE: Espar knockoff from Amazon

This one was more important than the exhaust pipe: after seeing photos of a 2006 Sprinter fuel sending unit, I realized there wouldn't be room to mount the giant washer that came affixed to the standpipe included with the CDH. The Espar knockoff had a much smaller footprint (so to speak). It also had a smaller inner diameter that matched the Espar knockoff fuel line (3mm). All of this is not just important, it's critical for a successful installation and operation.

• HEAT SHIELD WRAP FOR FUEL LINE: Flexible split sleeve protector from Amazon

This part is also very important. For our plan, running the fuel line from the tank on the driver's side over to under the passenger seat requires crossing it over the exhaust heat shield. Rather than risk melting our fuel line over time, we spent $20 on a sleeve protector. I also used it to wrap all the electrical cables within the passenger seat pedestal.

Those are the important (and dare I say critical) components. Even with those costs, the Chinese knockoff version of an Espar comes in at way too many factors less expensive than a legit Espar and we just couldn't justify the cost. As my wife reminded me when we were first building out our Sprinter, we have a beautiful home. She was right then and still is. This is just a van.

Ok then, with all of that covered, it's time to get to the actual installation. This took some time. Like, a few weeks of time, tinkering with it some days and spending hours on other days. Sure, I'm meticulous, but I'd clock this project around 60 hours if I had to go back and look at a time card. Who knows. It was significant.

Also, so worth it.

I'll list the steps out in order, including the steps where I ended up redoing (namely, carefully drilling the holes in the floor and then going back and cutting a big ol' rectangle). Speaking of…

Step 1: Measure and make the cutout(s) for the heater intake and exhaust hoses and fuel line

Like I mentioned, space is tight for this critical piece of the installation. Specifically, underneath the van there's about 5" of space between the step and an impenetrable frame member that runs the length of the van. Here's the space, first zoomed in and then zoomed out for context. Remember this is backwards/reversed to what it looks like looking down at the passenger pedestal. That frame member is on top in both pictures.

I tucked the placement of the bolts as close as I was comfortable to that frame knowing I'd need to get a socket on the nut to tighten it (so they needed to be far enough away to fit a socket). The catch then lies inside the seat pedestal. Given the constraints underneath the van, there's not enough room for the the metal mounting plate inside the pedestal. After much measuring and consideration (and wanting there to be more options), this is the only spot under the seat where a 2kW heater (and maybe 5kW, but the 8kW I believe is much larger) would fit (on the other side of that frame member is the exhaust heat shield).

Quickly, here is the original attempt after drilling 1-1'8" holes for the hoses and the other holes for the bolts and fuel line.

As I mentioned though, when I thought I was almost wrapped with this project I discovered I should probably have a larger cutout so the hot exhaust pipe doesn't essentially touch the van floor. So I broke out a cordless cutoff tool. BTW, I highly recommend one of these! It's a tool that has come in very handy for a lot of automotive and house projects (as well as for this project). Just saying. In order to get the mounting plate flat against the van floor, I had to cut away whatever material is adhered to it. I think it's some kind of vibration damping material. Whatever it was, it was rock hard and took a hammer and a putty knife. Sheesh. I scored it first with a utility knife.

The key to this placement is shown in the third photo above: the mounting plate fits under the lip of the pedestal. There's just enough gap for the thin sheet metal of the plate to tuck underneath, essentially holding that side in place. That said, I also had to cut off (with a, wait for it… cutoff tool!) about 1/2" of the plate in order to get it to fit.

I then drilled and installed M4 rivnuts (shown in the 4th photo above) and used accompanying bolts to hold that side of the mounting plate in place. It felt solid. Not perfect, but unfortunately in these particular Sprinters there just isn't a great solution for mounting them under the passenger seat. I didn't see any better designs. In fact, I never came across anyone putting a heater under the passenger seat in a T1N Sprinter. Hence, figuring a lot of this out as I went. Last thing, I painted the edges of every screw hole and the big rectangle I cut. No rust.

With that done, redone, and ready for the heater to be finally installed, it was time to shift gears and move onto the fun part: the fuel line.

Step 2: Install the auxiliary fuel line

This is where things got interesting. Fortunately, or not, we had experience dropping the fuel tank when we installed a passenger seat in our cargo van. Yay! So we knew what to expect. Mostly. At least for the dropping the tank part. Drilling into the sending unit would be an adventure. So then, the process for dropping the tank is a little involved. Cumbersome, but not impossible. Remember it's just a big plastic jug. Speaking of big plastic jug, I drove the van until the gas light came on so it'd be as light as possible.

DROP THE FUEL TANK

Step 2a: Remove the hose clamps holding on the filler hose and vent hose (driver's side). To make it a little easier, I also removed the Torx bolt holding on the fuel filler cap. It made the hose a little wobblier to help easing it off the port it connects to on the tank. First photo shows the filler hose, the second the vent hose, and the third of course the fuel filler.

Step 2b: Loosen/remove the (2) 13mm nuts holding the tank to the straps and get the tank out from underneath the van.

Before doing this, I built an "I" shaped platform out of scrap wood to the size of the tank and set it on a floor jack tucked up against the tank. It sort of worked. It didn't hurt, let's put it that way.

Once the tank was loose but not fully lowered, we had to finagle it up on the driver's side to lift and extend the straps in order to remove them and get them out of the way to drop the tank on the ground. Here I said "we" because this job is certainly easier with a second pair of hands.

This was a little tricky but again, not impossible. Then we could finally lower the tank to the ground. At that point, I had to break the clamps on the fuel sending and return lines as well as disconnect the electrical connection for the fuel pump. Breaking the clamps was a pain but, yep, also not impossible. I used a wire cutter and pliers. Thankfully, the tank then slides out from underneath the van without having to lift the van on jack stands or ramps.

Beautiful. FWIW, here are a bunch of photos of what between the top of the tank and the underside of the van looks like. They may be helpful to orient and see what's all going on.

The cables in the split loom tubing in the last photo above are the positive and negative 4-gauge cables for our 40A DC-DC charger that powers our house electrical system.

INSTALL AUXILIARY FUEL STANDPIPE

Step 2c: Drill and install an auxiliary fuel standpipe in the fuel sending unit.

With the tank revealed, it was time to pull out the sending unit and have a look. I'd read absolutely do not drill into the fuel tank! Instead, drill into the sending unit. Seemed like good advice. First, I plugged all the fuel hoses and cleaned up the top of the sending unit. 

Then I unscrewed the plastic retainer (ours came off easily although I'd read some say they had to hit it with a piece of wood + hammer to loosen the retainer).

Having read what info I could find about this critical (and a little intimidating) step in the process, I knew there was only one place to drill for the knockoff Espar standpipe. The orientation of the hose bib would also be important. A tip I had read to locate the spot to drill was to shine a light up through the lid of the sending unit. That revealed the plastic ribs underneath and made finding a spot to drill a piece of cake. Good tip.

The nut is the actual nut for the Espar knockoff pipe. This is why we couldn't use the standpipe that came with the CDH: the nut that would hold it in place was 4x the size of the Espar. I then drilled progressively bigger holes until I was at the 9/32" bit I used that perfectly fit the outside diameter of the pipe. I duct taped an empty cottage cheese container beneath the sending unit lid (just something that fit between the lid and the rest of the components of the unit) to keep the plastic bits from getting into the sending unit.

Worth noting: there weren't any instructions for how to install the pipe and I couldn't find anything definitive about how to install it. Specifically, did the O-ring go on the outside or inside of the unit. In other words, did it seal the top of the standpipe or the nut underneath. There seemed to be a depression in the underside of the hose bib that fit the O-ring perfectly, so I made the executive decision to sandwich the O-ring between the bib and the top of the sending unit. (read: on the outside). That left a bare nut to tighten on the underside of the sending unit lid. I needed to use a 1/4" 10mm socket and a needle nose locking pliers (plus adjustable wrench to hold the bib and keep it from spinning) to sufficiently tighten it because I couldn't get a socket wrench to fit. The last detail was the orientation. With all the other connections on the top of the sending unit, there really was only one way to orient the bib: parallel to the sending fuel line. Basically, pointing squarely across the van to the passenger side. It works great in that position for routing the fuel line to the heater.

For the last part of this step (2c, for those of you paying attention), I had to measure the precise-ish length I wanted the standpipe to be after bending it to fit alongside the body of the sending unit. To bend it, I had some spring pipe benders from a bathroom remodel long ago. I know those are used to bend rigid supply pipes without crimping or collapsing the pipe. I used the smallest diameter one to bend the standpipe around the body of the unit.

Then I measured the depth of the tank from the top of the lip where the sending unit screwed onto. It was 9" deep.

Here's the catch I read: the sending unit has springs and actually depresses when it's installed in the tank. Also, just as critical, I didn't want the pipe too close to the bottom of the tank. I'd rather us be able to start our van after a night of running the heater vs. a comfy van. Basically, I didn't want the heater using the last drop of diesel. I'd read 25-30mm (read: about 1") from the bottom of the tank is a good margin of error. These heaters sip fuel. With those measurements in mind, I checked and rechecked before cutting the pipe with a hacksaw. Note: I tried pipe cutters but they couldn't get small enough to fully cut the pipe. The hacksaw did fine.

Then checked my work. First, with the sending unit not compressed.

Then, with the springs fully compressed.

INSTALL FUEL FILTER (optional, but highly recommended to keep gunk out of the diesel heater)

Step 2d: Attach the fuel filter to the standpipe stub out with a rubber hose connector and short piece of the clear plastic tubing.

***Note: For the entire length of the clear plastic knockoff Espar fuel tubing, I encased it in the heat shield wrap I mentioned in the materials list above. It's easy to work with and is split lengthwise so the tubing can be easily inserted.

After tightening the fuel hose clamps, I felt good about that so I reinstalled the sending unit into the tank, making sure the retaining ring was threaded correctly and was tight. This took a few tries until I was convinced it was good to go. I also attached the fuel filter and rubber connecting hose for the next part of this step, which would be running the fuel line to the pump and ultimately over to the heater.

VERY IMPORTANT: The orientation of the filter. FUEL FLOWS INTO THE FILTER AND AROUND/THROUGH THE BASKET. In other words, the basket is connected to the lid of the filter on the outflow end of the filter! The manual for our CDH actually had it illustrated backwards (the basket on the inflow side) which led me to question this. Stupid manual. They're notorious for being poorly written and missing information. 

INSTALL FUEL PUMP

Step 2e: Attach the fuel pump to the underside of the van and run the remaining fuel line to the heater.

From the filter, it was onto the fuel pump. Yet another critical component of this installation. For our 2006 Sprinter, running a line from the fuel tank across to the passenger seat, there's a folded metal seam with holes every six inches or so running right to left just over the transmission crossmember. Perfection! I cleaned the section where I'd mount the pump in the center of the photo below. It made the perfect location to mount the pump and then run the fuel line directly over to under the passenger seat. 

The key to installing a fuel pump is the angle of orientation. For a CDH, the pump needs to be installed at a 25-35º angle with the outflow side of the pump higher than the inflow. Our manual stated 45º which I've never read needing to be the case and wouldn't have worked anyway using that folded seam. That seam does work to get the pump up to about 30º with which I felt good. I used the supplied rubber mounting gasket, bolt and nut to secure it through one of the holes in that wonderful metal seam.

Here then are a couple more photos showing the fuel line and filter coming out of the standpipe in relation to the pump (before lifting the tank back into place––it's still sitting on the ground). Note the orientation of the filter: the basket is attached to the output end (right side of the filter in the two photos below) going off to the pump. I left enough slack in that fuel line between the filter and pump to allow for the tank to be dropped (since it was still on the ground) without putting strain on it. This section of fuel line is about 3' (1 meter) long.

From the pump, I ran the fuel line (along with electrical cable for the pump, see below) right up against the underside of the van––over the driveshaft and exhaust heat shield. I used zip ties every hole along that seam until I met the longitudinal framing member next to the heater location above. Be sure not to tighten the ties too much or risk pinching the fuel line! I had to loosen all four Torx screws (I used a 12" extension on my 1/4" socket drive with a T20 bit) holding the exhaust shield in place to push it out of the way and access the holes in the seam. The last bit was running it down and around the frame and back up to connect it to the hose bib extending from the bottom of the heater. I was concerned whether or not this would work, pushing fuel down and back up the 3" to clear the frame, because there was no other way around. I spent time researching this only to find out––once installed––it works fine. Don't sweat it.

RUN FUEL PUMP ELECTRICAL

Step 2f: String the electrical cable with the fuel line between the pump and heater and make the connection to the pump

When running the fuel line from the pump to the heater, it's easiest to also run the electrical connection. The heater doesn't need to be installed at this point but the electrical cable for the pump does need to be threaded through the rectangle/holes drilled through the floor of the van! I ziptied the extra as shown in the photo above.

Okay, congratulate yourself. You've accomplished a lot and are possibly on the home stretch. Reinstalling the fuel tank involves reversing the steps needed to drop it. 

Before lifting it back up:

1. I reattached the two hanging brackets on the driver side so they were ready to have the tank lifted in place and then secured to the hanging bolts with the (2) 13mm nuts
2. I connected the wiring harness and made sure it was secure (listen or feel for a click)
3. I reconnected the fuel supply and return lines and secured them with fuel injector clamps like these (these ear hose clamps would also be acceptable, but I wanted to be able to remove them easier in the event we have to drop the tank for a third time––it is NOT recommended to use the more common hose clamps because they could cut into the rubber hose and don't squeeze with equal pressure around the circumference of the hose)

As we lifted it back up––BUT before it was all the way secured (i.e. there was still room between the top of the tank and the undercarriage of the van):

1. I popped the supply and fuel return lines into their respective clips attached to the undercarriage
2. Made sure the new auxiliary fuel line and filter were situated/not kinked/good to go (as I placed them they're still visible even with the tank fully secured)

Congratulations! If the tank and all of your hose clamps are secure, the filter and pump are oriented properly, and you have the electrical and the fuel line over to the heater, you can celebrate the fact you now have an auxiliary fuel line. Along with that comes the convenience of never having to fill or worry about a separate fuel tank or jug. It's a good feeling.

Step 3: Wire the electrical

This step is only as complicated as your electrical needs dictate. Very likely it's simpler than running the auxiliary fuel line. Unfortunately, with the mistake I made initially stringing 16-gauge wire from our fuse box to under the passenger seat as well as wanting our controller mounted pretty far back in our van, ours wasn't terribly straightforward. Also, since we have walls, galley cabinets and overhead cabinets, I had to remove several wall panels, three cabinets, the plastic trim piece behind the driver's seat, the driver's seat, and the floormat. Because of how we built our van, the wall panels don't remove nicely to get access where I needed it for the electrical. So I had to loosen them as much as I could and work behind them. All that to say, ours was a bit complicated. Bother all.

Like I mentioned, this part of the install won't be specific to any other build. Unlike the auxiliary fuel line which, if placing a heater under the passenger seat in a 2001-2006 Sprinter, will work exactly as described. Still, for ours we used:

• 10-gauge wire for the positive/negative power and ground connection
• 20-gauge 3-conductor wire to extend the length of the connection to the controller
• Heat shield covering for the wires under the passenger seat and between the pump and heater
• Since our 12v was coming from the fuse box (20A fuse that was supplied with the heater), I cut out the inline fuse that was part of the heater's wiring harness

That said, regardless of setup, there are three pieces to a CDH heater's electrical system:

1. The 12v power connection and ground (with 20A fuse, either inline or from a fuse box)
2. The fuel pump (completed in the previous step when routing the fuel line between the pump and the heater)
3. The controller (3-wire)

Finagling wires from the rear driver's side wheel well to the passenger seat took some work. Here are some photos in case they're interesting or useful. These first handful of photos are for wiring the controller.

To run new 10-gauge cables from our fuse box, I had to get creative. NOTE: since this run was about 20' from the fuse box to the heater, I opted to run a short 10-gauge negative to the factory grounding point under the driver seat.

The photo above shows the wire routing (along with lots of other wires from our electrical build for USB and 12v chargers mounted on the passenger pedestal as well as speaker cables from our rear 6x9 speakers we installed with our audio system) from behind the vertical plastic trim behind the driver's seat.

The last two photos above show the grounding point and the short, 10-gauge negative lead I ran from the heater. It was only about 4'. Having 12v power coming from the fuse box but not returning the ground to the fuse box only works because the box is connected to a negative bus that in turn is grounded to the van's chassis in the rear. If the fuse box was not grounded to the chassis, we'd have to return the negative wire to the fuse box. This is important! 

The last photo shows the cables protected by the flexible heat wrap. It may be overkill since both the factory seat mounts and the swivel seat bases we installed have a large cutout in the front that allows a lot of air in/out of the pedestal. If anything, the wrap kept the cables a little tidier.

Here are some photos of the heater electrical stats.

• At startup, drawing 7.57A (note the red glow plug symbol is illuminated at the top left-ish of the heater graphic on the control panel and the amp reading is bottom center of the Renogy battery monitor):

• Once the heater settled into maintaining the set ambient temp, it draws significantly less amperage (0.37A):

With the electrical complete, it was time to finally mount the heater before installing the final two pieces: the intake and exhaust pipes.

Step 4: Install the heater along with output hose, intake pipe and exhaust pipe

This really is the homestretch. Still, there are a few important considerations:

• Keep the exhaust pipe as short as possible
• Mount the CDH muffler with the drip hole facing DOWN so water that accumulates in the combustion process can drain
• Maintain a downslope throughout the entire run of the exhuast piping so water can drain (if it cannot and pools somewhere in the drain pipe it will eventually rust)
• Make certain the drain pipe sticks out from the side of the van so carbon monoxide does not build up under the van
• Avoid making any sharp bends in the exhaust pipe
• Do not point the intake pipe forward to avoid sucking in bugs and dust whilst driving

Even given those considerations, the intake and exhaust were straightforward. This would work for any T1N Sprinter installation where the heater is under the passenger seat. I extended the intake straight down from the heater, made a bend and secured it to the underside of the step. For the exhaust, I ran an 18" section to the muffler which I also attached to the underside of the step, then clamped on an additional 6" to extend it slightly from the underside edge of our van. For the muffler, I used the supplied bracket and sheet metal screws (with nylon washers).

Last came the output hose. That's right, the thing that actually brings heat into our van (!). Though installing a heater under the passenger seat of a T1N van left only literally the exact position where I mounted it (no right/left wiggle room, and I had to balance allowing some space for the air intake at the front of the heater while keeping in mind the output hose), I was a little concerned the output hose wouldn't make the bend to the outlet that really could only be mounted in the small depression on the backside of the seat pedestal. Sheesh.

To mount the hose, I first drilled a 2-3/8" hole using a hole saw and some cutting oil, followed by 1/4" holes for the bolts. Then I painted the edges of the cutout before mounting the outlet. I had to source the #8 bolts and nuts I used (they weren't supplied in the CDH kit).

With the heater mounted, I used (yep) my cutoff tool to shave off 1" increments from the outlet tube until I felt confident it would comfortably make the bend without any kinks. I didn't want kinks in case that caused a buildup of heat back inside the heater, triggering an error code and/or shutdown. In the end, though stiff, the tube made the seemingly impossible bend easily. I'm not sure if it would have worked to position the outlet on the right side of that depression, but I chose the left side to put it that much closer to the center of our van as well as give the tube the best chance of fitting.

With that, it's the moment of truth. Yikes. After however many hours, days, weeks, maybe months… it's time to see if the heater fires up! Since our fuel line was about 8', I knew I needed to activate the manual pump mode on the controller. Before doing that, I installed the fuse and watched the controller light up. First success! Then I engaged the manual pump mode and listened to it start clicking. I crawled under the van, pulled back an inch or two of the heat wrap so I could see through the clear pipe, and waited for the telltale sign of fuel and bubbles moving slowly up the line.

And waited… and waited. I ran the pump a second time, then a third. At last! On the third cycle, I saw fuel working its way past the pump. I then pulled back a bit of the wrap just beneath the heater. Once I saw fuel at that point, I shut off the pump to avoid flooding the heater. I then turned on the heater, at which point the pump engaged to push the diesel the last bit up into the heater. After another couple of anxious minutes while the heater did its startup routine, it started blowing hot air! Success!

I let it go for a good fifteen minutes while I checked some of the heat output with an infrared thermometer at various points in the system.

• Output tube: 150º
• Heater casing: 110º
• Exhaust pipe close to the underside of the van: 100º
• Exhaust pipe at its end: 90º

Based on these findings (primarily the readings on the heater casing and output tube), and arguably a little overkill, I took the side plastic cover for the seat pedestal over to our router table and turned it into a vent. It's not my finest work but honestly, at this point I was ready to be done with this project. Routing thin plastic is a little, well, jumpy. Also, this'll do the trick. In hindsight, it would have worked better to place a piece of scrap wood underneath the plastic cover to keep it more rigid while routing.

The final, final step was having my inspector come in to sign off on all the work. She's a tough one to please, but ultimately gave me the thumbs up. Phew!

With that, we now will have heat in our van. Glorious heat. Like I said at the start, this project was massive. It's also one I've been wanting to tackle for a few years now. Heck, since we first built out our van. I can think of so many nights spent in the van where having a heater would have been glorious, as well as all the nights we didn't spend in the van because it was, well, winter.

Again, some of this post is very specific to a T1N van (please benefit from all that I learned and screwed up!) as well as generic to any diesel heater. Time will tell if my installation is truly successful, but given all that I learned, did, and redid, I'm feeling confident.