Off Grid Hot Water- My D5/Isotemp install (a photo essay of my installation).

Phew. My van build is finally winding down. Like most adults, our DIY builds go in stages where we are busy building and spending tons of money, then it takes a break for months.

Thanks to the inspiration I received from GeorgeRa, Hein, MidWest Drifter, DieselFumes, and a few others, my dream of hot showers and true off grid diesel fired water is done.

There are a number of solutions for hot water, from simple to complex. We've used solar showers for years. And solar showers with boiling water poured in, and a Mr. Heater portable hot shower, and the IsoTemp with electric element connected to shore power. All of this was leading up to the eventual installation of true off grid hot water.

I chose to use an internally mounted IsoTemp Slim Square 15L heater. Hein and GeorgeRa used exterior systems. I'm fortunate to live at 6300' part of the year, so having more freeze resistance was important. Plus I have the dream of buying an Epic Pass or Ikon Pass and spending a winter skiing in the van (with hot showers).

My cost for the D5/IsoTemp system was roughly $2600. I bought the IsoTemp Slim Square for $750, and the D5 with install kit and high altitude when the pound was weaker (just after the Brexit vote) for about $1250. Add in $500-600 for miscellaneous parts and coolant expansion tank.

On to the pics.

Photo 1- The venerable IsoTemp Slim Square Marine hot water heater with coolant loop heat exchanger and 750 watt electric heating element.

Photo 2- The engine coolant connections for the IsoTemp. No flow direction, just hook up an inlet and outlet. This can be run via a D5 or similar, or via an engine coolant loop. There have been a number of discussions on personal preferences here. I chose to keep the Hot water system and engine system separate- for now. I didn't want to have a tank of 185F water inside the van on 100 degree days every time I drove the van. In the winter time, it may not be an issue.

Photo 3- The IsoTemp is bolted in place and going I am running the coolant lines. You'll see that I used 10-series 8020 for the water cabinet. On the right side is my 25 gallon water tank (that straddles the wheel well). Between the IsoTemp and 25-gallon tank, I can hold 29 gallons of water for trips.

Photo 4- I am going to pass my coolant lines and drain hoses just in front of the wheel well. It's actually a great spot, since it is shielded on 3 sides from water coming off the tires.

Photo 5- I used a 4.5" Marine Cable boot with ring (available Amazon or West Marine). Makes a great wiring or plumbing pass through. This is just testing the plumbing run.
 

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More pics!

Photo 1- Prepping the coolant lines for installation. I wrapped all internal plumbing lines in 1.5" heat shield. Expensive stuff, but I didn't want a 185F heat sink inside the van. Even after running for 20 minutes, it's cool to the touch.

Photo 2- Running the drain lines. I ended up with three drains for my water system: water tank drain, water heater safety relief drain, and a drain in a low point of my cold water.

Photo 3- Everything is a tight fit. I used the heat shield to pass my coolant lines over the exhaust pipe and drive shaft. The heat shield provides abrasion resistance as well as insulation for my coolant lines. Keeping coolant water hot and heat (mostly) out of the living space.

Photos 4&5- The heat shield I used. 1.5" heat shield is a bit oversized, but I needed to pass hose clamps and 90 degree bends through it through it as well. Took a bit of wrestling inch by inch to pass everything through.
 

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Part 3- Bleeding air and passing coolant lines under the van.

Pics 1 & 2-
Passing coolant lines under the van. I've since cleaned up the routing since these pics were taken. The red heat shield is the outgoing (hot) coolant line. The black line is the return (post heat exchange line). After these pics were taken, I cleaned up the zip ties and swapped them all to high heat zip ties from Hellerman Tyson (available Amazon). The zip ties are for HVAC and are rated to continuous use at 300F (150C). Where the system passes over the exhaust system I also used stainless steel zip ties. The metal zip ties are quite sharp and a pain to use, but they work and should provide additional heat resistance over the drive shaft.

Hellerman Tyton Zip high temp zip ties- https://www.amazon.com/gp/product/B00D8PUXTC/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

Stainless Steel Zip Ties- https://www.amazon.com/gp/product/B071NYQD9H/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1

Heat Shield- https://www.amazon.com/gp/product/B004GMI8NO/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1


Photo 3- Installing the heater and under the van. More on this later.

Photos 4 & 5- Installing a bleed valve in the system! I installed two of these at high points in the coolant line runs in order to bleed air from the system before the first startup. I read and re-read GeorgeRas troubleshooting of his own system and decided to install them ~before~ I had any issues with air in the system. They worked great. Prior to turning on the system for the first time, I jumped the coolant pump with a test lead and ran cold unpressurized coolant through the system for about 20 minutes. Lots of spitting and hissing from this valve on startup. Finally a steady stream of coolant with no bubbles. I also did the same at the opposite end.

By running the system cold, I was able to run it with the cap off on the coolant expansion tank and listen to it burn and belch as it slowly purged air. Worked great, flooded the coolant lines easily, no troubleshooting of air locks in the system.
 

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Next round of pics Installing the D5.

Pic 1- The D5 Hydronic II. After reading about George's issues with the integrated coolant pump, I was happy to see a new version with an externally mounted pump. Didn't increase the height of the system, could be mounted in any position (and elsewhere in the coolant run), and could be easily turned on with a set of test cables.

Pic 2- Installing it under the driver's side bay. Man it was dirty under there. I scrubbed it out a bit first to limit the amount of road grime falling into my eyes while under the van. The usual holes + painting all the holes + Plus Nuts.

Pics 3 & 4- My homemade Plus nut installation tool. Works just as well as the $60 Plus Nut tool, but for only about $6. Also. Anti seize goes on all Stainless steel bolt threads! This area will have a lot of road spray. Protect your threads. Drilling them out would be no fun if they galled up.

Pic 5- Getting closer...
 

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Air intake and completing the installation of the D5 heating unit-

Photo 1- After crawling around under the van and musing about how to squeeze in the D5 into the factory location directly under the driver's door handle, I found this manual showing a double D5 installation. I installed my D5 in the spot just behind the fuel fill tube. Super easy and a huge open spot to work with. Made for an easy install with space to work and clean routing of intake, exhaust, coolant lines, and electrical connections.

I've mused about putting an additional fuel tank here, or more water. But in reality, I'm probably done with the build at this point. If an additional fuel tank becomes a must have item, I can move the exhaust forward and easily fit a second 10-15 gallon tank in the empty space.

Photos 3&4- I would have liked to have the air intake for the heater in a higher, dirt free location. I had to settle for tucking it into a frame rail. It's as high as I could go, relatively dust free, and has lots of other openings to draw air.

Photo5- Teeing off the Aux fuel tap with a simple Dorman connector. The left side runs to my Airtronic D2. The right tap runs to my D5. All fuel lines are protected from abrasion with 1/4" split loom.
 

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The coolant expansion tank-

A huge thank you to GeorgeRa for checking EBay for small coolant tanks. Thank you George! This little one gallon coolant tank was sold as a NOS Espar D5 coolant tank for a Marine system. A little dented, but otherwise in perfect shape. Snapped this up in a hurry, and it works fine.

I mounted the coolant tank on top of my Van Compass compressor mount. I bought one of their prototype onboard air mounts in October 2016. I had my onboard air system (Viair 450C with 2 gallon tank) here for over a year, but moved it under the van to accommodate the coolant tank. I think I can also just barely squeeze in an old fire engine air horn on the mount as well.

I was a bit concerned that I wouldn't have enough coolant volume in the system with only a 1-gallon tank. So far so good though. With my long coolant line run (roughly 35' total) and the tank half full I'm running just over 6 liters of coolant in the system.

Photo 3- running the coolant lines from the tank past the steering linkage. Once again, everything is a tight fit! Hard to tell in this pic, but there is about 1" of clearance to the steering linkage. I wrapped both lines in Heat shield for abrasion resistance and just to keep my 185F lines from contact with other engine parts.

All of this is probably overkill on my part. In the end though, I'd rather overbuild the system and not think about it for the life of the van...

Photo 4- I also used some leftover heat shield to wrap the electrical harness. My electrical harness passes over the muffler and exhaust. Again, probably overkill, but protects it from road spray, heat from the D5 exhaust, and abrasion.
 

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Connecting the electrical and purging air from the system-

The installation kit comes with tons of wire for the coolant pump and fuel pump. Because everything was located really close together, I was able to eliminate nearly 30' of extra wire. Of course, Eberspacher didn't provide any extra crimp connectors, so I had to cut off both ends. I shortened them with heat shrink butt connectors, and an additional layer of heat shrink.

I saved the unused fuel pump wire, and made a switched test lead to the coolant pump. This was based entirely on Georges troubleshooting issues with his install. As I mentioned before I was able to circulate coolant with the system cold and unpressurized. I opened each of the bleed valves a couple times till they stopped hissing and spitting. Because the system was cold, I was also able to just open the cap on the expansion tank and let it burp air out of the system. I added extra coolant twice as the system filled.

Photo 1- shortening the extra wiring. Much cleaner than zip tying a large bundle under the chassis.
Photo 2- All the leftover wire.
Photos 3&4- My water system controls.

Of note is that I put my IsoTemp electric heating element on my shore power connection with a 60 minute timer. No need to run the system longer than 60 minutes. The IsoTemp comes with a plug, but no indicator light or anything to let you know that the 750W element is running. I just wanted more control in case I heat water in my driveway and get distracted an onto another project.
 

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Last comments-

If you can install an Espar Airtronic D2/D4, you can install this. It's basically the same system. The Airtronic heats and moves air; the D5 Hydronic heats and moves fluid.

My system fired up perfectly and trouble free on the first attempt. This was partly due to the short runs for coolant pump and fuel lines, and more due to reading, and rereading other's troubleshooting stories and addressing them early in my install.

I've only fired it up 4 times so far. It. Is. Awesome! :rad: Warm water in 10 minutes, and 6-7 gallons of 100F+ water in about 20 minutes. My dream of hot showers is complete and was the last major task of my entire van build.

Clean, warm, dry, and a comfortable place to sleep is the holy grail for DIY van builds. Got those knocked out and more...

I wouldn't have been able to tackle this project without asking questions of the forum members who came before me, and particularly to GeorgeRa who documented his troubleshooting issues and resolutions, and answered many of my questions along the way. After many hours of research, planning, and building it in my head, I installed it with cleanly without issue. I'm also satisfied that my installation is probably more professional than many pros. No shop would spend time wrapping most of the coolant runs in tough heat shield, or taking the extra time to shorten wires, wrap every wire and fuel line in split loom, and tidy up everything.

When summer is over and freezing temps return, I will likely try to have the D5 connected to my engine as a pre heater. Not quite clear on the layout of solenoids and valves, but I imagine a solution where I can use the D5 as a winter engine pre-heater for cold starts, or for hot water, or both. May be as simple as a couple of isolation valves to separate the coolant loops. At this point I don't see the need to have the IsoTemp connected to the engine coolant loop (especially during hot summer months), but that may change.

I'll be happy to answer any questions or post up additional pics. Also working on a more detailed blog post describing the whole install in detail.
 
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GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
Last comments-

If you can install an Espar Airtronic D2/D4, you can install this. It's basically the same system. The Airtronic heats and moves air; the D5 Hydronic heats and moves fluid.

My system fired up perfectly and trouble free on the first attempt. This was partly due to the short runs for coolant pump and fuel lines, and more due to reading, and rereading other's troubleshooting stories and addressing them early in my install.

I've only fired it up 4 times so far. It. Is. Awesome! :rad: Warm water in 10 minutes, and 6-7 gallons of 100F+ water in about 20 minutes. My dream of hot showers is complete and was the last major task of my entire van build.

Clean, warm, dry, and a comfortable place to sleep is the holy grail for DIY van builds. Got those knocked out and more...

I wouldn't have been able to tackle this project without asking questions of the forum members who came before me, and particularly to GeorgeRa who documented his troubleshooting issues and resolutions, and answered many of my questions along the way. After many hours of research, planning, and building it in my head, I installed it with cleanly without issue. I'm also satisfied that my installation is probably more professional than many pros. No shop would spend wrap most of the coolant runs in tough heat shield.

When summer is over and freezing temps return, I will likely try to have the D5 connected to my engine as a pre heater. Not quite clear on the layout of solenoids and valves, but I imagine a solution where I can use the D5 as a winter engine pre-heater for cold starts, or for hot water, or both. May be as simple as a couple of isolation valves to separate the coolant loops. At this point I don't see the need to have the IsoTemp connected to the engine coolant loop (especially during hot summer months), but that may change.

I'll be happy to answer any questions or post up additional pics. Also working on a more detailed blog post describing the whole install in detail.
Great write up and congratulation. Based on what I have seen done locally your system is very professionally done. Once you experience hot water in camping there is no turning back. Well done!
 

Midwestdrifter

Engineer In Residence
I believe you can rig up a "hydraulic separator" which will allow heating the engine without any extra valves. You will need to run a coolant pump on both engine and D5 loops. Basically a relay to run the engines aux coolant pump when the d5 is running would suffice.

The advantage of a this design is that you do not need a second expansion tank for the D5 loop, and all flow is isolated in each loop unless you run the pumps for both loops.
https://www.caleffi.com/usa/en-us/b...spaced-tees-have-worked-just-fine-me-30-years
 

Mickyfin

Member
Superb writeup, very helpful, I already have the D5 installed from the factory, and plan on maximising its use for my water heater too. Already found the EU supplier of the Isotherm 15L from here https://www.ebay.co.uk/itm/Boiler-I...-00/264074136178?_trksid=p2485497.m4902.l9144

I pretty much want the exact same setup as yourself, so will be using this thread as reference for my complete conversion.

Would it be possible for a detailed list of all components used to complete your install please? Would be extremely helpful, and appreciated, I can then add those to my forever ongoing shopping list, and then when the spring arrives, I can get onto my van conversion work.
 

VinceP

2005 158" High Roof Pass.
I'm thinking of installing such a system in my future camper build.
I already have the D5 from factory with the 7-day timer (can run engine off) and I have the Supplemental heat exchanger at the rear (passenger version) with the plumbing there. I'm thinking of an Isotemp connected to the engine system. For avoiding having hot water in the summer when not required, I was thinking of using the actual electric valve that is already installed that isolates the rear heater core when the system is off. (I would obviously remove the rear heater core permanently, and install a D2 or a D4 under the passenger seat).

Anyone had the rear heater already installed when modifying for hot water?
 

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