Ventilation & Heating
To live in a van comfortably and long-term, you’ve got to dial in how to keep your interior at a comfortable temperature and humidity. Moisture control is often an overlooked issue for first-timers building out their van. But after spending a few nights breathing warm air in cooler temps and waking up to condensation on your walls and ceiling, you’ll quickly learn that there are a few things you have to do to keep you and your van healthy and condensation-free.
In this post, we’ll go into three things that will keep your van’s temperature comfortable and help you mitigate any moisture problems.
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Table of Contents
Absolutely essential for living in a vehicle to vent moisture and heat.
Optional for some but essential for us since we plan to travel and stay in cold places (hello skiing!).
Part 1: Ventilation & Fan Installation
TL;DR: Installing a fan is essential for keeping comfortable and maintaining your van — and installing it is DIY-friendly and inexpensive.
Hot air rises and holds more water vapor than cold air. Having a way to vent out that heat and moisture is crucial to long-term living in your van if you don’t want mold, rot, or excessive heat and humidity in your van.
Maxxfan v. Fantastic Fans
Luckily, installing a roof fan is relatively easy and cheap! The two popular products here are the Maxxfan and the Fantastic fans. The Maxxfan has a cover that can keep rain from entering the van even when it’s open and running, whereas the Fantastic Fan has to be closed when raining (but it does close automatically thanks to a handy-dandy sensor). Here’s the thing: you usually want to be running your fan when it’s raining, because that’s when you want to ventilate out some of that humidity and wet clothes inside your van — so we got a Maxxair 00-05100K MaxxFan Ventillation Fan. Bonus: you can leave it open while you drive. Pair an open fan with a window rolled down, and you can air-out your van in no time.
Installing the Fan
There’s nothing quite like the buying your new dream-mobile in all its shining glory and immediately finding a power tool to cut a gaping hole in the roof. Installing a fan in your van is actually a pretty easy task that can be done for less than $400 and finished in one day.
Step 1: Decide Where to Put the Fan
There’s really two locations you’ll want to consider for where to best place the fan. Option one is in the middle of the van — it’s nice and centered and can draw out cooking heat/smells pretty easily. Option two is in the back-third of your van — we chose this because it’s over our bed (and we ultimately want it to keep us comfortable in hot weather) and we’re planning to cook outside a lot.
Another very important thing to consider when placing your fan is what else you’ll put on your roof. If you’re planning to put a large solar array up there — figure out how much room that’ll take up and where you’ll put it! You don’t want to install a fan first, then later find out that you can’t put solar up there. We got lucky with ours and had a few inches to spare between our fan and our solar array, but if we had placed our fan a few inches further back we could have added a lot more solar.
Step 2: Mark the Hole
Next, you’ll have to mark the cutout on your van so you know where to cut the hole. Luckily, your fan’s plastic flange (the part that actually slides through the hole when you’re finished) doubles as a guide for marking your cutout!
Here’s what you’ll do: first, locate where you want the fan to be placed by measuring how far back/forward you want the fan to be, then finding the van’s center. No shame in measuring this three times. Once you’ve figured out where you’re going to cut the hole, you’ll want to mark it by placing painter’s tape on the ceiling and marking the cutout with a marker.
Step 3: Drill and Cut the Hole
Next, you’ll use a drill to punch a hole through the four corners of your square. If you want to practice drilling a hole first, you can make a mark in your cutout and drill through it first. Always remember to wear safety glasses and a hat, because hot metal chips are going to be flying when you drill and cut. You’ll want to have a vacuum ready to suck up those metals shards, too, because if you leave them on your van floor and walls, they’ll rust.
OK, so now you’ve marked the hole you’re going to cut and you’ve drilled four holes in the corner — time to grab the jigsaw and connect the dots! Cut a side, then use duct tape to tape the cutout to the van, and repeat. If you don’t tape the cutout to the van, then the cutout is going to fall as you’re cutting which will make your line wobble and is a safety hazard.
Now you’ve got a hole in your van! Use a metal file to smooth out that cut so you can run your finger over it.
Step 4: Install the Fan
Place your flange on the roof, clamp it down, and pre-drill the holes for where the screws will go that’ll hold the flange down. Once you’ve got those pre-drilled, remove the flange, sand those drilled holes, then apply primer, paint, and clear coat to everything you’ve drilled/cut so far. You don’t want those to corrode down the line!
We really didn’t want our fan to leak — especially if it was going to mess up our insulation and ceiling. So, we bought a roll of butyl tape to sandwich between the van’s exterior roof and the plastic fan flange on top. Take your time and make it nice and even, and be sure to not miss any spots. (Update: we’re really glad we used butyl tape on our build — we’ve had zero issues with leaks 1.5 years in, even when water is literally sitting on top of the roof. Rad!)
Almost finished! Now place the fan’s flange in place over the butyl tape and screw it into place. The butyl tape will probably compress and squeeze out on the sides — you can use a boxcutter to carefully remove that extra tape, but be sure not to cut your van’s paint in the process. Now for the last step: place your fan unit through the flange and use the 4 screws to secure it in place.
Ta-da! Your fan is now installed! If you’re going to have an electrical system to power it (highly recommended), the highest speed only consumes 2.8 amps, so you can use a 3.5 or 5 amp fuse for it. Then, just run an electrical wire to your DC fuse block. Not confident with electrical work yet? Check out our Electrical System guide.
Part 2: Heating & Types of Van Heaters
TL;DR: If you want to travel in the winter, invest in a vented heater. We recommend the Webasto Air Top 2000 with a thermostat.
Getting a heater in your van opens up so many more places to travel year-round instead of confining yourself to seasonal adventures or heading south for the winter. There’s nothing quite like waking up on a snowy January morning to find yourself in a winter wonderland and making a warm breakfast before hitting the ski slopes. If traveling in cold places isn’t your thing, go ahead and skip this section and move on in your conversion!
There are two kinds of heaters you can install in your van: non-vented and vented heaters. Both work by combusting a fuel source (propane, gas) to create water, carbon dioxide, and our favorite by-product: heat.
Non-vented Heaters
Non-vented heaters – like running a propane heater inside your van – mean that the combustion takes place inside the van. That means it releases carbon monoxide in your van (dangerous!), adds water vapor to the van (mold/mildew!), and doesn’t come with a fan to help circulate the air so your van is evenly heated. The perk is that they are easy and inexpensive to add to your van – you can head to your local hardware store and have it up and running in, like, ten minutes.
Side note: you can technically use an electric heater to heat your van without having to worry about carbon monoxide or water vapor, but we don’t advise running an electric heater in your van unless you have a beefed-up power system to run it — they’re energy hogs! Plus, you’ll be using it in winter, when your solar panels won’t be getting as much sun during the day to recharge your batteries as fast as in the summer.
Vented Heaters
Vented heaters are physically located inside the van, but the combustion takes place outside the van. Most models use your gas tank or a propane tank as the fuel source, which is really convenient. Vented heaters mean carbon monoxide never comes inside the van (no asphyxiation – yay breathing!), it doesn’t add water vapor to the van and actually reduces your relative humidity (goodbye mold and mildew; hello drying damp clothes inside), and it has a built-in fan that helps to distribute your heat evenly. We’re big fans of vented heaters (pun intended).
Most new vented heaters have an optional a thermostat, which means you can set it and forget it while you’re outside of the van. The older models run on an on/off switch, which isn’t nearly as convenient. It’s worth the money to get a thermostat!
Vented heaters only have one disadvantage: they’re expensive and may require professional installation. Installing them involves tapping into the fuel line or mounting a propane tank and doing a lot of work cutting and bolting the heater to your van floor in really tight places. That’s might be more than most folks’ bargain for — and may be above your experience level if you don’t have experience with fuel tanks.
Unless you know what you’re doing, we don’t recommend trying to do this yourself. This is the one and only thing we had professionally done on our conversion. We probably could have done it ourselves (tapping the fuel line isn’t as hard as we thought), but with the amount of work involved, we were happy to pay someone else to do it.
We got our heater installed at a mechanic shop that specializes in custom HVAC systems for commercial vehicles — most metro areas will probably have one of these available. If you get a Webasto heater, just check their dealer locator. While the mechanic worked on our van for four hours, we grabbed coffee next-door. $2,200 later, we came back to a heated van.
We’d recommend investing the money and installing a vented heater. You don’t have to worry about carbon monoxide poisoning (a very real and serious threat in a small living space), it helps to reduce your moisture levels instead of making them worse, and it’s super convenient to have heat that runs automatically off your fuel line. Big improvement!
Which Heater to Buy
The two best heater models are the Webasto Gas Air Top 2000 (also available for diesel) and the Propex HS2000. The Webasto has a little more heating power (7000 BTU/h over Proper’s 6500 BTU/h), but the Propex is a little quieter inside and outside of the van. Both have a thermostat. The Webasto is slightly more convenient, because it runs as long as your fuel tank is above one-third full. You’ll have to monitor and re-fill your propane tank periodically for your Propex. However, the Propex has a better track record for reliability — it burns clean and doesn’t get clogged with soot, and it also tends to work better at higher elevations. Far Out Ride has an in-depth Webasto v. Propex comparison between the two models (and they installed both heaters in their van).
We liked the idea of not having to monitor an external propane tank, so we went with the Webasto. We’re happy with our decision and our warm van.
Part 3: Condensation Control
We’ll start with the bad news: living in a small space like a van means moisture will condensate in your living area, which could lead to mold, mildew, and rotting building materials. There’s nothing you can do to completely eliminate condensation in your van.
The good news: there are plenty of steps you can take to minimize condensation in your van so it won’t be an issue for you. We already covered a few of them above, but we’ll go into the many tricks of the trade you can use to make sure condensation doesn’t affect your van or lifestyle. Thanks to these tips, we’ve never had a long-term condensation problem in our van.
In brief, the goal is to combat condensation in your van by reducing the amount of moisture inside (by ventilating your living area with your fan) and by insulating/reducing the cold spots in your van (which condensate when the cool air outside meets your warm interior).
Intake-Outake: Maximize Your Fan & Window Ventilation for Less Condensation
It’s worth repeating what we wrote above: having a fan to ventilate your van is going to drastically reduce the condensation in it. This works best when your fan is venting air *out* of the van and you have another source as an intake, like an open window. This is especially true when you’re sleeping and your warm breath gathers condensation on your van walls and ceiling.
Aside from leaving your fan open and running, you’ll want to crack a window so that your air flow has an intake, too. That means a nice cross-breeze will circulate through your fan, taking your moisture and odors right out with it!
We’ve got two tips for cracking a window to help reduce condensation:
1. C.R. Laurence Windows
C.R. Laurence’s T-Vent Windows have two vents that you can manually open to get a lot of air flow going on in your van. Since your fan is likely 14” by 14”, you’ll want a similar amount of area for your open window (aka air intake). CR Laurence windows can keep up with your running fan to make sure your cross breeze is nice and powerful. It’s less stealthy, though – so keep that in mind if you’re parking on the street.
2. Rain Guards for Front Doors
If you don’t have a nice T-vent on a window to use for your air intake, rolling down your driver and passenger windows an inch or two is your next best bet. The problem? You’ll want a rain guard to keep the rain out (and yes, you’ll definitely want to be running your fan / ventilation system in the rain). Bonus: it’s even more stealthy, and passers-by might not even realize your front windows are open while you relax inside. You stealthy, well-ventilated van dweller, you!
If you need even more ventilation than a cracked window and roof fan are providing, you might consider getting a box fan or a smaller fan to help the air circulate more. You can even get a 12V Box Fan that run smoothly off your electrical system. We’ve never needed this.
Other Tips to Reduce Condensation
It’s time for lightning round! If moisture is still an issue in your van, here are some tricks you can try out to help get it to a manageable level:
Insulate Correctly
You read our guide on insulating your vehicle, right? Then you know that thermal bridges can lead to a lot of condensation — and you’ve already minimized that! All those cold metal surfaces that would have been in your van already have a radiant barrier working to reduce that temperature difference. Hooray! Plus, you’ve already taken moisture into consideration when selecting an insulating material, which means that even when you do get condensation in your van, it’ll be much, much less likely to lead to mold and mildew.
Use Window Covers
This is your biggest bang for the buck. When it’s colder outside, the warm air inside meets the cold outside air on all of your windows, which leads to condensation building up on the inside of your van. To avoid it, make a tight-fitting window cover out of Reflectix/EZ Cool for all of your windows while you sleep. That’ll create a barrier between the warm and cold air, which means condensation on the windows will be non-existent or manageable enough to simply wipe a microfiber over when you wake up.
In the Winter, Insulate Your Fan
You’re not going to be running your fan very often in the winter, because all your heat would just get sucked right out of the van. So to reduce condensation from gathering on your fan and seeping into your ceiling and insulation, you’ll want to create a 14” x 14” insulation square to shove in your fan for the winter. You can buy a RV Vent Insulator online or make your own from leftover Reflectix/EZ Cool and foam/Thinsulate/insulating material you used to insulate your van.
Add Air Flow Beneath Your Mattress
Your body will produce a lot of heat on your mattress while you sleep, and if your mattress heats up but your mattress frame is relatively cold, moisture can lead to mold growing beneath your mattress. Not exactly a place you’d like to sleep! Luckily, it’s really easy and cheap to fix this problem. Just buy some Aire Flow material and cut it to size to place beneath your mattress. Now that your mattress can breathe, you can breathe a sigh of relief (puns make this guide more fun to read, right? … R-right?).
Reduce cooking, drying clothes
It might be unavoidable, but these could lead to about a half liter of water being vented into your home each day. Getting rid of it at the source is easier than trying to get rid of it in the atmosphere, but your style of van life might mean that’s not feasible.
Think about a Dehumidifier
Dehumidifiers help to reduce the amount of moisture in the air, but it won’t eliminate condensation. That’s because condensation happens when the warm inside of your van comes into contact with cold surfaces. Running a dehumidifier can still help to bring your moisture levels down into a more comfortable range, but it’ll also suck a lot of power, too. Still, this is looking into if you need the extra help.
Cat Litter Doesn’t Work So Well
Moisture absorbents like cat litter and desiccant work for small spaces (yes, even smaller than your van’s living area). They can work in your drawers or storage boxes — but they won’t be able to keep up with the interior of your entire van.
Hope that helps! Taking steps to control your van’s climate is well-worth the time and effort. There’s nothing like stepping into a comfortable van when the weather outside is less-than-ideal.
