DIY Diesel Heater In-a-Case

[Wolf Island Diver]

Here’s my diesel heater build. It’s basically an improved clone of a Planar heater. Total cost was cheaper than a Planar but still $500+

First, some quick background. Wabasto had a patent on these heaters which lapsed years ago, hence the cheap Chinese knockoffs. Theres a lot out there and despite different ratings, they’re all basically the same unit. Output ratings are a function of the pump frequency and even those are basically the same when tested. I’m not going into the pros and cons of these or the process to build them because there’s a mountain if information out there.

If you want to build one you need to start with this gentleman’s YouTube page which goes in-depth on everything.

https://www.youtube.com/@johnmck1147

Another source I used is this page:
https://warmda.com/how-to-install-diesel-heater/

Here’s what I did thats notable and perhaps different than many of the ones I’ve seen out there.

1. RotoPax fuel tank. I didn’t want to use the included tank. For one I didn’t want to necessarily store the heater in the truck with the fuel. I also don’t want to have to pour fuel into the heaters tank at camp if I don’t have to. Lastly drilling a port on the bottom of the tank increases chances of a leak, and pulling fuel from the tank bottom where the crud is. My solution was to use a RotoPax and standpipe. This way my heater’s fuel rides mounted on the outside of the truck and I can put the heater wherever. I don’t have to pour fuel. Standpipes are just better and more flexible for alternative fuel sources or depth. It’s not shown inserted here, but when the standpipe is in the RotoPax in place of cap, it’s sealed. When not it use it’s secured on top. All of this is easier to replace and maintain as needed.
   
   
   
2. The heater draws its heating air from inside. This is how heaters should work. If you can run a return from your tent, then it’s fine to penetrate the case and draw air from outside the case from the return. If you’re not running a return, you definitely don’t want to pull in cold ambient air to the heater. That can’t be easily avoided for the combustion air but for the heating (secondary side) air, I draw air in from vents on the case where it’s warmed up by the interior temperature of the box. This has the secondary effect of keeping the interior temperature under control, drawing it out of the case. The risk from CO is not significantly increased. Seal the exhaust well. There are other failure modes of these heaters internally that can create the risk of CO regardless of air source. These are safer than a Buddy heater, but they’re still using combustion. You should use a CO monitor with any combustion based heating including in your home. Additionally, this is essentially the same design as the Planar heater and other clones, which have been proven. This design significantly increases efficiency
   
   
3. Better wiring. I’m not the first to do this but my wiring for the remote and power cables are detachable through waterproof ports. Also I have nice long cables and they’re easier to store and replace. I also wired the plug end compatible with a 12v waterproof plug wired into the bed of the truck and a 12v power plug adapter for running off a Goal Zero
   
   
   
4. Better Intake. The stock thing that comes with these heaters is not a filter. It’s more of a poor intake muffler. Throw it away. It actually promotes insects and debris getting in the heater which can damage it. I used a real filter and upgraded smooth radiator hose for the intake.
   
   
   
5. Better components. I upgraded the exhaust hose and hose clamps (regular hose clamps are inadequate), fuel filter, mounting bracket with a custom fabricated one and screws/bolts
6. Floating fuel pump mount. This moves the fuel pump away from the other components and into a better position, allows for easy maintenance and priming. You should manually prime the pump from the tank up through the filter. The pump is lubricated by the fuel, so you should minimize running it dry. It’s easy to remove the bottom connection from the pump.
7. Better exhaust routing. Because condensation forms in the exhaust, you want to start high and move downwards. I’ve got plenty of room to run a good length exhaust pipe, muffler and tail pipe sloping downward without hitting the ground.

I’ll post a parts list once I compile it.

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[Wolf Island Diver]

Quick update.

I got around to testing and this performs better than I could have imagined.

My priming method with a squeeze bottle worked perfectly.

Secondly, my pump mounting was wildly successful at damping the tick of the pump. You have to be about 6 inches away to hear the pump at all. Beyond that, the sound of the air blowing, which is a pleasant white noise, completely drowns it out. In fact I kept thinking the pump had turned off and there was a problem.

Lastly, internal temperatures remained stable and high temps were localized to the obvious places like the exhaust. On its lowest frequency, this puts out fantastic dry and odor free air. This is going to be great for camping, emergencies or in my workshop in lieu of electric baseboard heat.

 

[ToJTornottoJT]

Excellent. What is a "Standpipe"?

 

[Wolf Island Diver]

Excellent. What is a "Standpipe"?

That’s the copper tubing that goes down into the fuel tank. By drawing from the top you eliminate the possibility of leaking from a fitting drilled into the tank. In other words the tank isn’t compromised. Also you can change out tanks easily since the top of the standpipe seals against standard fuel canisters. I’ve got a typical dual RotoPax mount, so I’ve got two tanks of fuel, but I could also use some other tank if need be. Longer standpipes are designed to go down into the vehicles fuel tank opening to draw from that tank. There’s a single penetration in the case for the fuel line, but overall it’s less integrated. So I could replace all the fuel lines in a matter of minutes if need be.

 

[813 Fabrication & Design]

That’s the copper tubing that goes down into the fuel tank. By drawing from the top you eliminate the possibility of leaking from a fitting drilled into the tank. In other words the tank isn’t compromised. Also you can change out tanks easily since the top of the standpipe seals against standard fuel canisters. I’ve got a typical dual RotoPax mount, so I’ve got two tanks of fuel, but I could also use some other tank if need be. Longer standpipes are designed to go down into the vehicles fuel tank opening to draw from that tank. There’s a single penetration in the case for the fuel line, but overall it’s less integrated. So I could replace all the fuel lines in a matter of minutes if need be.

Any issue with losing your prime when swapping tanks or removing the standpipe to refill the tank? Do you keep the lid a little loose when using the heater so that it is slightly vented to prevent too much suction?

 

[Free2roam]

That’s the copper tubing that goes down into the fuel tank. By drawing from the top you eliminate the possibility of leaking from a fitting drilled into the tank. In other words the tank isn’t compromised. Also you can change out tanks easily since the top of the standpipe seals against standard fuel canisters. I’ve got a typical dual RotoPax mount, so I’ve got two tanks of fuel, but I could also use some other tank if need be. Longer standpipes are designed to go down into the vehicles fuel tank opening to draw from that tank. There’s a single penetration in the case for the fuel line, but overall it’s less integrated. So I could replace all the fuel lines in a matter of minutes if need be.

So the fuel tank is attached directly to the case. Correct? How hot does it get? Or not at all? Curious I'm thinking of doing mine with fuel tank inside separated from the heater by a piece of plywood. Not in a case but in the back corner of the camper under the bench area. In the empty area there

 

[Wolf Island Diver]

So the fuel tank is attached directly to the case. Correct? How hot does it get? Or not at all? Curious I'm thinking of doing mine with fuel tank inside separated from the heater by a piece of plywood. Not in a case but in the back corner of the camper under the bench area. In the empty area there

Basically all of these heaters-in-a-case attach the tank to the back of the case and on the other side of the back wall of the case is the heater itself. Those don’t seem to have issues. They includes the DIY and commercial versions like the Planar. Mine’s different in that the RotoPax mount let the tank stand off slightly from the case and that that RotoPax case itself is way heavier than the cheap tanks that come with the Chinese heaters. Also the heater stands off from the case by about 1/2 inch, so it’s got air flow all around it. Diesel fuel in the truck is moving through lines in hot environments, those hoses aren’t melting and diesel fuel itself is pretty safe when heated. I don’t think heat will be an issue. These heaters are also designed to move air through them which keeps the case cooler as the heat is moved out through the exhaust and the output. They can and will overheat if the fan fails or if you shut them off without a proper shutdown cycle. In that case it’s conceivable there could be damage to the case and tank but that would be an extreme situation.

Despite not being all that concerned based on all the other successful similar designs, I did a lot of checking inside and around the outside of the case with a laser thermometer when testing at temperature and didn’t find heat spikes or heat soak issues. I was more worried about melting wires. The highest heat is inside around the exhaust port on the heater itself and the warm air output.

Your overall use case may be different than mine. I wanted to have a portable case but I wanted to be able to separate the heater and fuel for convenience and safety/mess and so I could pack the heater in the truck without regard for potential spillage. I could theoretically ditch the tank and draw fuel from my trucks tank with the standpipe, but I don’t see myself doing that. In your case you make just want to mount the heater somewhere and the tank where convenient and not even worry about a case. A lot of vans folks mount the heater under the chassis.

I highly recommended watching those YouTube videos linked. That guys stuff is really informative.

 

[chorky]

I bet you could just put one of these inline with that setup.....

https://www.amazon.com/JRL-Primer-R...efix=1/4+inch+fuel+primer,aps,220&sr=8-3&th=1

I like the idea OP has about relocating the pickup to the top of the tank instead of the bottom.

 

[Wolf Island Diver]

I bet you could just put one of these inline with that setup.....

https://www.amazon.com/JRL-Primer-Rubber-Motorcycle-9001080A/dp/B07H2Z6GJ8/ref=sr_1_3?crid=31VDNQO9XAY3H&keywords=1/4+inch+fuel+primer&qid=1693148854&sprefix=1/4+inch+fuel+primer,aps,220&sr=8-3&th=1

I like the idea OP has about relocating the pickup to the top of the tank instead of the bottom.

Originally I was going to use one of these, but that thing is 6 inches long. That’s a huge bulb for this small heater and I didn’t want this huge bubble of fuel sitting in the case. I couldn’t find one that was significantly smaller. It really needs a primer bulb the size of a lawn mower, or weed eater. At one point I was going to fabricate something to mount a lawnmower priming bubble but decided that simpler was better. If a simple squeeze bottle did the trick without making a mess, it would work. The bottle works really well so I haven’t seen the need for something else.

One thing that might work well is a plunger primer for an ATV or Jetski, and those can be mounted.

Carbpro Fuel Primer Plunger Pump Kit 11305/10161-AD With 3 feet Fuel LineSnowmobile/ATV for Kawasaki Skidoo Yamaha https://a.co/d/4CGQeh5

 

[chorky]

Originally I was going to use one of these, but that thing is 6 inches long. That’s a huge bulb for this small heater and I didn’t want this huge bubble of fuel sitting in the case. I couldn’t find one that was significantly smaller. It really needs a primer bulb the size of a lawn mower, or weed eater. At one point I was going to fabricate something to mount a lawnmower priming bubble but decided that simpler was better. If a simple squeeze bottle did the trick without making a mess, it would work. The bottle works really well so I haven’t seen the need for something else.

One thing that might work well is a plunger primer for an ATV or Jetski, and those can be mounted.

Carbpro Fuel Primer Plunger Pump Kit 11305/10161-AD With 3 feet Fuel LineSnowmobile/ATV for Kawasaki Skidoo Yamaha https://a.co/d/4CGQeh5

Good check I didnt even think to look at the length. I bet there is a smaller one available somewheres.

I have been pondering getting one of these. Yes it's a cheapie. But its a good base start and one can always replace the actual heater with a name brand later on...
https://www.amazon.com/gp/product/B0BM5M4BV8/ref=ox_sc_saved_title_1?smid=A26VV9GYKZP35X&psc=1

 

[Wolf Island Diver]

Good check I didnt even think to look at the length. I bet there is a smaller one available somewheres.

I have been pondering getting one of these. Yes it's a cheapie. But its a good base start and one can always replace the actual heater with a name brand later on...
https://www.amazon.com/gp/product/B0BM5M4BV8/ref=ox_sc_saved_title_1?smid=A26VV9GYKZP35X&psc=1

That’s an incredible price. It’s probably just as good as the next one. There really is only one name brand and that’s Webasto. The reason there’s a proliferation of these heaters is Webastos patents ran out. Pretty much all the Chinese diesel heaters are the same. Even the watt rating doesn’t seem to mean anything.

 

[chorky]

That’s an incredible price. It’s probably just as good as the next one. There really is only one name brand and that’s Webasto. The reason there’s a proliferation of these heaters is Webastos patents ran out. Pretty much all the Chinese diesel heaters are the same. Even the watt rating doesn’t seem to mean anything.

Eberspacher is also a well known brand option in line with quality like Webasto.

 

[Wolf Island Diver]

Eberspacher is also a well known brand option in line with quality like Webasto.

That’s true, but again since the Chinese ones are essentially clones, I’m not sure I’d spend the money outside of maybe outfitting a sailing yacht. The Chinese versions seem to cut corners on stuff like the “air filter,” fuel filters, quality of clamps, etc. I replaced all of that stuff. While I’m frequently skeptical of Chinese knockoff products it’s also clear that in general increasingly a lot of them are the exact same product rolling off the same assembly lines in the same factories in China as the name brands. A good example is small bench polishers where a $20 no name product is clearly identical to the $200 version. Increasingly the name brands are having their products made in China throwing a different casing or label on the same product rather than this just being these Chinese makers stealing designs or tooling. You see this with hand tools, Mac Tools is famous for this but even Snap On does it now. You see it with power tools like drill presses, ice makers, mini fridges, Solar panels, etc. I’ve been a big proponent of “buy American” for years. I paid $200 more for the same VPP mountain bike frame from Intense over Santa Cruz a few years ago, solely because it was made in Temecula Ca, rather than Taiwan. I still refuse to shop at Walmart on principle. But increasingly I’m losing sympathy for these companies that are just passing off Chinese clones on us. I’m not saying Webasto is doing that although I’d be surprised if they were actually made in Germany. But the prices for what is just a cast heat exchanger and a fan is pretty ridiculous.

 

[Free2roam]

Can basically buy 10 Chinese ones for the price of the others and only get one.

 

[Wolf Island Diver]

Can basically buy 10 Chinese ones for the price of the others and only get one.

Exactly. There’s a point where you could keep spares just in case they’re not as good. Again, if I was sailing the North Atlantic or somewhere where ordering replacements would be an issue, I’d probably grab an expensive one. But for car camping, I’m not going to waste my money.

Again I recommend folks who are interested in DIY’ing one of these watch this guys vids. He’s done the yoeman’s work on the CDH’s. Of course the fact that “CDH” is a thing tells you just how popular a solution these things are. Between my Born bedroll and my heater I’m really looking forward to winter camping this year without worrying about CO poisoning and a soupy tent from a Buddy heater.

https://www.youtube.com/@johnmck1147

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