Webasto Dual Top Evo 6
To get the most out of my Sprinter campervan, I wanted it to be usable in all weather conditions. This meant a heater was a must. The most common RV heating solutions run off propane, but there are some heaters out there which run directly off the vehicle’s diesel fuel tank. I wanted to avoid the added complexity, space, and hassle of another fuel which would be required if I went with propane, so I opted for one of the diesel solutions.
As I have a shower in the van, I really wanted hot water as well. Luckily, there is a combined air / water heater that runs on diesel made by Webasto. The Dual Top series is made to install either inside or outside the vehicle, and provides from 6-8 kW of air heat as well as 11 liters of hot water. I looked around at a couple other options, but this was the one that seemed best suited to my needs. I went with the Dual Top Evo 6, which is the base model in the series. I didn’t really care about being able to run off shore power (which the Evo 7 and Evo 8 offer), and the 6 kW of heat output should be plenty for the Sprinter.
Fabricating the mounting bracketry for the Dual Top
Unfortunately the Webasto Dual Top series is meant to be an OEM product, so if you’re a DIY’er like me, it can be hard to get much info on the product. It’s also hard to figure out how to buy it, but there’s a site online where you can find them. I ordered mine and it showed up from overseas within a few days.
The Evo 6 is quite big, so for me the only practical spot to mount it was under the vehicle where the spare tire normally lives. I took some measurements and it looked like it would fit there, although even in that space there isn’t a ton of extra room. Figuring out how you will route the air ducting is one of the first steps, as it dictates which direction you’ll want to mount the unit. For my build it made the most sense to pull cool intake air from the back of the vehicle through the gear area. The hot air would have one outlet run up to the main living area and one outlet placed in the gear area to keep air circulating back there.
Having access to metal fabrication equipment is key, as the Dual Top will need mounting bracketry made up. Note that the heater is quite heavy, even when not filled with water, so it’s important to make the mounting bracketry really sturdy. Imagine bouncing down a rough dirt road with that all that weight hanging on your brackets – it pays to overbuild here.
Mocking up the bracketry
Evo 6 in its mounting cradle and ready for final install
Next is hooking up electrical and plumbing. This is pretty straightforward if you follow the instruction manual. Make sure to put in some shutoffs in your plumbing so you can run your water system without the unit filled. A crossover between the cold supply to the unit and hot exit is also helpful (with a valve, obviously), so you can send cold water to all fixtures even if you aren’t using the unit. I’ve found that I rarely actually keep water heated, and when it’s below freezing the unit will automatically drain if it’s outside the vehicle / heated space. One additional note, if the unit automatically drains itself, it’s important that the supply pump is turned off otherwise it could drain the entire water tank! I keep my water pump on a switch, and make a habit of turning it off when not in use. I also usually have the unit drained and valves to it shut off to prevent any issues in freezing temps. Hot air ducting is pretty straightforward as well, just make sure to order the right components and minimize ducting lengths (there is no hot air distribution componentry included with the unit).
Plumbing lines going to the heater, pay no attention to the mismatched colors…
Cover for the plumbing which also serves as a duct for the intake air
After I got everything hooked up, I fired up my Dual Top Evo 6 for a test run. It took a couple tries to prime the fuel system, but then it started up and began blowing hot air! I used the unit without issue for a couple weeks, and then it began having some problems. It wouldn’t turn on and blow hot air, and would only heat water intermittently. This persisted for a few weeks until it stopped working completely. I spent some time going through troubleshooting with Webasto’s U.S. Technical Support team, who were very helpful. Unfortunately it didn’t look like a simple issue. I ended up visiting their facility and they were able to diagnose the problem as a loose pin in the wiring harness. Since getting that fixed, the unit has been functioning great!
Working well after getting the loose pin diagnosed and fixed
So what are my thoughts now that I’ve been using the Evo 6 a while? I’m definitely happy with how it performs. It will heat the vehicle up quickly when I need, and heats water relatively quickly too. My biggest complaint is related to the automatic draining function. There is an option to keep the unit in Frost Protection Mode, where it will maintain a minimum amount of heat to keep water in the boiler from freezing and draining. However, you cannot control the cabin temperature in this mode. To effectively heat the interior of the vehicle and have the boiler not drain itself, you have to keep the unit in Cabin Heat / Hot Water mode. This works fine, but it keeps the water at 70C and the Dual Top has to run a lot to maintain this water temp. It would be very nice if you could select a combination of Cabin Heating and Frost Protection modes, so that the cabin could be heated while only maintaining a low water temp.
Another consideration is electrical power consumption. I haven’t measured the actual amperage draw, but when the Evo 6 is running frequently my house batteries get run down fairly quickly. It certainly doesn’t help that the warmer I keep the inside of the van, the harder the fridge has to work as well (also electric). This isn’t necessarily a complaint, just something to make sure to keep in mind when sizing a battery bank. I have 180 AH of Lithium Ion batteries, and fully charged it seems these last about 1-2 days in sub-freezing temps if I keep the interior around 50-60 F.
Finished install, after more than a few trips down wet dirt roads
The last big takeaway I have is I’d strongly consider how important having hot water really is. It’s awesome to be able to take a hot shower when it’s freezing outside, but for how infrequently I use it, cold showers would probably be bearable. If hot water isn’t a necessity, there are many smaller air heaters that are cheaper, simpler, lighter, easier to install, and likely draw less power. I think if I did it again, I’d likely skip hot water and go with an air only heater.
Overall, I’m quite happy with the Webasto Dual Top Evo 6. I would definitely recommend it if you’re looking for a solution that includes air and water heating and runs off diesel. Any specific questions, let me know in the comments!
Great post! could you pass on the name and number for the person you talked to at Webasto. Past experience was they did not know much about the EVO 6 in the US office.
Thanks!
Bob, I also found that knowledge was limited about the Dual Top, but if you can get ahold of Tracy he’s the guy for these! I don’t have a direct number for him, but you can call the general tech support line and ask for him.
Steve, thanks for the name. Will see how I make out. As a point of reference, I have talked to the folks in the UK and they are very helpful. The only downside is the call can be expensive!
Steve, where did you find to order it from. I’m having a hard time finding a dealer. Thanks.
Jason, I ordered it from Heatso.com out of the UK. They had it in stock, and were the only place I could find it online. Shipping was pretty quick and easy. I didn’t have to pay import fees or anything.
Steve: great post & very helpful.
I wonder if you could share the details on how you successfully connected the DUAL TOP EVO 6 to your diesel fuel tank?
Thank you
Joe,
My Sprinter has an auxiliary fuel tap installed from the factory, so it was as simple as removing the plug from the auxiliary tap and connecting the Dual Top fuel line with the right adapter.
Best of luck with your install!
Steve
Steve:
Thanks for the response. My Sprinter does not have the KL1 Aux Fuel Tap but I will check with my MB dealer to see if I can order & install.
Joe
Do you remember what was that connector that fit on the kl1? thank you!
Sorry, I don’t know what the specific connector needed was. I think everything necessary to connect to the factory fuel tap was included in the kit though.
Steve:
Admittedly I am new at the DIY game but I appreciate SO much the input of others like yourself & to that end wanted to share what I have learned on the chance it helps someone else particularly with a Sprinter.
I found a solution that does not suffer the limitations of the EVO that you shared. I chose the Webasto Thermo Top C300. Ironically, a Webasto product as well & the unit has been around since 2010. Not available in the USA so I ordered it from a Webasto dealer http://butlertechnik.com/
in the U.K. (hassle free & free DHL, here in 3 days, duty $80 to Uncle Sam). It is essentially a throwback I am guessing since it pre-dates the hot air “technology” of the EVO in that it is “just” a hot water heater.
What makes the C300 unique is even though it’s an exterior mount, it’s small enough to nestle in on the frame below the driver’s seat ahead of the fuel tank just like MB does with their Espar Diesel engine heater (in fact there is room for both – I installed both since I wanted 4 season use (at altitude) & the engine heater “*” allows the Sprinter Diesel to actually start sub 20F (something my Ford Diesel Excursion would never do), less wear on engine & also it heats the front cab area through the vehicle’s own stock heater system in the dash).
“*” The Espar I chose is the newest S3 with whole lotta whiz bang improvements which in the event of the retirement ever of my new Webasto C300 will be substituted (my research & purchase decision came too late to effect that harmonization of diesel heating units).
Like the Espar engine heater the Webasto CV300 heats an antifreeze solution which instead of being plumbed into the engine cooling system is piped to a small heat exchanger inside the Sprinter (it you locate the heat exchanger close to the CV300 & the shower close to the heat exchanger it amounts to instant on hot water). The heat exchanger heats potable water for demand hot water use & also to multiple radiator style heater fans to heat the interior (I am actually thinking of putting radiant in floor heating by simply adding it to the loop – it could be on the antifreeze filled loop to eliminate sub-zero draining for storage. So, as long as the interior is above 32F there is no issue with frozen potable water lines & in the event you were storing the Sprinter in the dead of winter (for a dash to the Tropics) you only have to drain the potable water at the heat exchanger (maybe a gallon in the average shower & a couple of fan heater radiators). A little bit of creativity locating the hot water outlets for shower & sink as well as fan heaters can get that loss of water down to less than a gallon.
Happy Trails.
Joe
Thanks for the great info Joe! I briefly considered a similar system, but it seemed at the time more complicated that I wanted to get. I’ll definitely consider it if I ever do another build though.
Hopefully others will find your review helpful as well!
Steve
Hey Steve, Tracy from Webasto here. I stumbled upon your site and thought I’d chime in on a few things. If anyone else is considering buying from Heatso, just be aware that Webasto in North America cannot honor the warranty, it has to go through the UK. I’ve had some folks say that they can’t get in touch with Heatso after the sale, but I’m currently helping a gentleman that is having great success with them on a warranty issue. It’s just a slow process at this point because of the distance. Just an honest ‘heads-up’ for anyone considering purchasing from overseas (and I totally get it).
The other issue is with frost protection and cabin heat. If you are using the heater for cabin heat, you are effectively preventing a freeze condition, assuming your water lines are inside the return air duct, and I think they are from the looks of it. That return air will be just a few degrees below ambient. The only concern is any lines/valves, etc. that might be outside of that return air duct and outside of the heated space.
Take care Steve!
Thanks for the info Tracy! I’ll have to keep that tip in mind next time the temperature drops. I thought keeping the unit in cabin heating mode could be an effective method of preventing freezing / draining, but didn’t see that option in the manual and wanted to be safe.
Appreciate all your help. FYI, my dual top is running great and I’m still enjoying it regularly.
Hello Tracy……I have a dual top evo 6 in my van and the anti freeze mode won’t close! Water keeps pouring out of the heater even when I try to close it by turning the knob to “drain down” again, as the manual says??? IS THERE A SERVICE CENTER ON THE WEST COAST? CHRIS
Hi there. I can think of a simple way to stop the 15G from freezing. Cycle water from the 10G to 15G in a loop via pipework that probably already exists. Simply put in an INLINE pump (only very low wattage is needed, it only needs to be a trickle…or pulse every hour or so when outside is freezing…ebay has plenty of 12v timers, and just have a thermostat to tell it to run or not….I can help with further info if needed on wiring etc). Of course you need to be cautious you don’t freeze both the 10G and 15G.I don’t think that would happen though given the 10G is inside the van. My guess is, it would average the two temperatures of freezing and whatever the van is. You’d also wrap insulation around the 15G (maybe a box and fill it with spray foam…easy to do and cheap). Personally I’d move to warmer climates (just kidding).
None of this stuff is hard or expensive. Stop paying top dollar for simple stuff.
Hi,
I bought the dual top evo,6, and I have a sprinter. I don’t want to remove my spare tire and I know thats the only place it will fit underneath. So,I want to put the unit inside the van instead. I know its designed to be outside. I will build a drain which dumps outside for the automatic drain function and also for the exhaust . I am wondering if you think this unit is too loud to be inside?
Hi Steve,
The unit is actually designed so that it can be mounted inside or outside. If you can get ahold of the installation manual, it will show the details for interior installation.
I don’t think it would be too loud. There is a fair amount of noise that comes through the hot air ducts anyway, and I doubt it would be much more with the unit inside. You could probably put some insulation around the enclosure for the unit to dampen noise as well.
Best of luck with your installation!
Steve
Tracy, Can you provide the name of a few Webasto suppliers in the Pacific Northwest that handle the EVO6?
In my experience, there are only three ways to get a dual top in the US.
1. Pay for a licensed installer to buy it from Webasto USA. $2700 plus whatever they want to charge you to install it (probably thousands more)
2. Become a licensed installer with Webasto USA. This requires you to take a three day install class and spend abut $5000 plus the heater, which they want to sell to you for $2700 (while claiming they are giving you 40% off). This class is something you have to try to schedule with them and they will not sell you the heater before you take the class.
3. Buy it from Heatso.com this is a retailer based in london and they actually sell it cheaper than webasto USA with their “discount”. Webasto USA doesn’t like these guys and don’t know how they are getting the heaters and they claim they are not covered under warranty (which is a lie). The shipping time is quick if you fill out a IMPORTER ID INPUT RECORD from DHS form #19CFR 24.5 Fed ex will provide you the form before they can deliver but it stalls the delivery for a week.
Hi Chuck,
I doubt Tracy will see this, so I’d suggest just giving Webasto US a call. As you probably found, their Dealer Locator doesn’t work for RV products.
I do know that XP Camper is on the West Coast and handles this product.
Steve
Hello Steve,
Thank you for taking the time to write up this article, it’s extremely helpful.
It looks like you’re using pex 1/2” water lines. What adapter specifically did you use to connect that line to the Webasto?
I just received an Evo 6 and laying everything out for an install.
Found my own solution.
Uponor (Wirsbo) 3/8” PEX line fits perfectly with the 10mm barbed connectors included with the unit. ??
Glad to hear Tom. That’s the same thing I did, just heat the 3/8″ PEX a little and it fit right onto the barbs!
Hi Steve,
Thank you for the article. It is very helpful. Is there any chance you would be willing to share the plans for the mounting bracket you fabricated?
Thanks,
Richard
Hi Richard,
I would be happy to share if I had any plans, but I just made the bracket with the unit mocked up in place, and didn’t write down any of the measurements.
Steve
This is great, thanks! I just received my Dual Top and bought it from Peak RV in Colorado. Will be installing it in a gas Transit with a small aux diesel tank, probably around 5 gallons. It’s a bit problematic finding the right spot for it, but I think it will to in front of the spare tire behind the transmission.
Glad you’ve found it useful Sally. Putting in an aux diesel tank is an interesting solution. Hope it works out well for you!
I am finally getting around to installing I the Evo and have a couple of questions. How big did you make the return air hole? The manual specifies 100mm but it looks like you used some PVC as a thru-hull. Did you attach the bellows-like flange directly to the PVC underneath the van? Also, do you have a source or recommendation for the hot air output ducting? Did you use metric or 3”?
Curious on this question on what size of ducting he used. I am looking for 80mm ID but it is hard to find the air outlets that will match.
Sally: I’ve tried to locate the RV dealer you mentioned (Peak RV), but I’ve NOT been able to do so. Would you consider providing some contact info . . . Thank you ;-). Rick
This is way late, but anyhow the guy from Peak moved temporarily to Canada for work and said he was temporarily Suspending that business.
Hello Steve,
Last year I also installed a dual Top evo 6 on my sprinter.
Unfortunately I have troulbes with the electrical power consumption.
As you wrote, with 180Ah capazity it runs about 2-3 days. I reach similar values.
But how do you load the batteries again?
If you charge it while driving with approx. 30A you will need a 6h ride. (I have 2 100Ah lead-acid batteries)
In normal conditions I drive only 0.5-1h every day.
Do you see any option to reduce the el. power consumption or to lower the battery loading time?
Thank you very much
Gokula
Hi Gokula
Yes, I also run into the problem of keeping my batteries charged in the winter when I don’t drive for very long. I have three ways to charge my batteries:
1. Charging from the alternator when the vehicle is running. I actually just changed this so that I’m charging directly from the alternator instead of connecting through the vehicle battery. A quick test gave me 45A going into the house batteries instead of about 25A previously. That was with the house batteries at 13.1V. I’m hoping this helps keep my batteries more charged from driving short distances. I used 6GA wire, and if I did it again I might even use 4GA. Note that lithium ion batteries can be charged at a very high C factor, so high charging rate isn’t a concern for me.
2. I have 200W of solar to charge the batteries as well. I don’t get much out of this in the winter though, maybe 15Ah per day max.
3. Last I have a 120V battery charger installed. I plug into shore power in the winter whenever I have the opportunity.
I don’t have any recommendations for reducing the power consumed by the dual top, other than keeping the temperature set lower so the unit doesn’t run as often.
Good luck, hope you find a good solution!
Steve
Did you insulate all the outside pipes? what did you use? thank you!
No I didn’t. The pipes are designed to be run inside the intake air ducting from the vehicle’s interior, and my intake ducting just consists of the flexible boot connected to a PVC pipe uses to penetrate the floor, so it is very short. The unit will circulate air periodically to keep these pipes from freezing when in the appropriate mode of operation.
Hi Steve,Thanks for the great write up. I actually have done a Dual Top installation as I work for an outfitter, first Dual Top for both of us. We did not get to much time to get a proper shakedown of the unit outside of seeing it put out a lot of air heat! The water heating seemed slow and I wonder how well it’s ability to maintain on demand hot water for something like say a shower is. Tracy was quite helpful with tech questions and the like, and says he experienced nearly an hour for the hot water to reach the high temp, 70 C / 150+F. It seems a 20k BTU heater should be able to heat water faster.. an hour to heat up, then you have 11 liter / 3 gallons to use in effect? Would you be willing to share some real world experience of your hot water usage in time and temperature terms? I would appreciate it as I am looking at this heater as an option right now, and having installed and tested the Rixen/coolant style system, I am not sure this Webasto could keep pace in comparison. Thanks in advance and keep up the good work. Chris
Thanks Chris! I think Tracy’s feel of an hour to fully heat is about what I’ve experienced.
Agreed that this is very slow given the unit’s output. I did a quick calculation, and heating 11 liters of water from 15 C to 70 C over an hour only requires 0.72 kW of power. I suspect the unit isn’t designed to direct the full 6 kW of power to water heating, and isn’t really meant to be an on demand water heater.
I’m not the best person to ask about effectiveness of this setup. I have my van set up for boondocking, and thus am always very mindful of my water usage. When I do use the shower I try to keep it as short as possible (maybe 3-4 minutes of actual water run time). That said, the hot water will last for two short showers in a row without significant temp drop. Keep in mind you’re mixing hot and cold water at the showerhead to get the desired temp, so you effectively get probably more like 5-6 gallons of hot water.
Hope this helps! Feel free to get in touch via email if you have further questions or want to chat more.
Thanks for the reply Steve. I am at the conclusion also that this is not meant to be an on demand hot water source and not this units strength in the long run. I’m assuming your using another heating method for say cooking water, and the dual top is good for showers and dishes let’s say, and not coffee water! I really like the unit, it’s all in one compactness, and the friendly controller, but feel there is a better hot water heating option. Thanks again and enjoy your travels.
Wanted to add to the thread…we were having issues with our evo6 cutting out from time to time this fall/winter. Then finally it appeared to die; no power at the control unit at all. Did all the basic trouble shooting. Didn’t find anything. Dropped off at my service guy (DM Truck and Trailer in East Earl PA for those on the east coast) they found the main connection had some corrosion on the pins. Also replaced with connector with a waterproof connection and bingo unit has been working flawlessly for the past two week. Our unit is mounted under the van in front of the spare tire.
So if anyone has theirs mounted under the van something to consider!
Thanks for the write up, just fitting one myself so very useful. Have you used this cooling air intake cover – https://www.butlertechnik.com/webasto-heater-parts-c111/webasto-dual-top-cooling-air-inlet-cover-60%C3%B8-1314904a-p2363? And if so what have you attached on the end of it?
Hey Olly, I’ve done an external installation with this part fitted and there is a small grill piece that you can get that fits over the end.
I’ve been having problems with moisture getting inside the unit through the cooling intake leading the circuit board on the heating intake fan corroding… Trying to work out if I can fit a 60mm hose to the cooling intake to keep the worst of the weather out. From Steve’s pic above looks like he’s got the part fitted pointing downwards with a short hose connected, so might try that. 2 replacement fans so far and quite expensive.
Olly, sorry I missed your comment. The one I used looks similar, but I thought it came with my Dual Top. It is short and pointed down. I don’t have a hose attached to it, although I agree that would be a good idea to help keep moisture out. I wrapped a piece of metal screen over mine and secured it with a hose clamp. Haven’t had moisture issues in the unit that I’m aware of.
On a somewhat related note though, I did get an error where the control panel couldn’t communicate with the main unit. I disconnected the electrical connector that lives outside the van next to the unit, and sprayed some electrical cleaner and dielectric grease on both sides of the connection. That did the trick. Seems like that connection, although a weathertight connector, is prone to some water intrusion and corrosion.
Nice shower!!! I have been following #vanlife for a while and plan to build one for myself one day. I have always thought about having the shower in the middle of the floor because it would easily stow simply! Yours is definitely magical engineering at its finest! I love where you’ve got the water and wh! I also love that you used a regular shower on the inside rather than the tacky RV stuff. I’m great with anything on the back that isn’t seen but your bathroom is just totally impressive.
Also very impressed with the folding foot of your bed and the bench that drops for more foot room. Those are awesome!
Thank you! Yes, I find the standard shower works well, and is definitely higher quality than the RV stuff. Glad you found it useful and hope it helps with your build!
anyone know about the main board problems with the evo 6
This being one of the very few discussions on this unit, I thought I’d add an update on my install here. We installed the Dual Top under our 2017 Transit, just behind the rear axle. It fits nicely there. Amazingly, it worked the first time we tested it, but when we got out to Wyoming it failed with a fuel pump short or open circuit error. We never got it working after that. I am in the middle of working with Tracy from Webasto. USA to repair it. I took the service cap and cooling cover off to access the control unit and I’ve traced out the circuitry all throughout the fuel pump power circuitry. It tests fine on the bench and yet when I button it back up it fails. Tracy thinks it is a faulty harness. Perhaps these harnesses have had some problems.
Tracy is awesome, btw.
Hi Steve, just curious, what error codes were you getting when you had initial problems? And which pins did webasto track down that were causing the problem? I’m currently stuck in the mud trying to figure some problems out with my dualtop, which has been awesome for 3 years until this one
Outstanding post, I think blog owners should acquire a lot from this website its really user genial.
So much wonderful information on here :D.
E-bikes, capable of speeds reaching up to 28 mph, redefine the essence of commuting by seamlessly blending sustainability with an exhilarating ride experience, making them a sought-after choice among urban travelers seeking eco-conscious options for transportation. Emitting zero emissions and flaunting an impressive range of up to 100 miles on a single charge, e-bikes stand tall as eco-warriors on wheels, significantly curbing carbon footprints and ensuring prolonged rides without the need for constant recharging.