How to Install a Maxx Air Fan

Next up in our build series is installing our Maxx Air fan. This isn't Maxx Air fan specific so if you were wondering how to install a generic fan in your camper then you have reached the right place. Follow along on our journey where we will explain step by step the journey we took to install and fit our fan.

If you are new here, thank you for stopping by. We are in the process of converting our 2015 Ford Transit (a.k.a 'Faith') into our home on wheels (Cliché I know!). Armed with the lessons we had learnt from installing the side window we were ready to tackle this challenge. We gave ourselves plenty of time so that we didn't work into the evening and got to it.

What is a camper ventilation fan?

A fan, or ventilation fan, in simple terms is a large fan that bridges the inside of the van to the outside. Its soul purpose is to extract the moisture and stale air from the inside of the van to the outside. In our case, we have chosen the Maxx air 7500K - 350, which also has the ability to reverse the direction and instead bring the outside air in (nice on a hot day!).

In order to prevent rotting and moisture building up in your van you need to have a constant supply of fresh air moving throughout. When you carry out different activities such as cooking or just sitting and relaxing you are producing moisture and heat inside of the van. A good example of this is boiling water, that's why in most houses there is an extraction fan to remove the moisture build up.

We have chosen the Maxx Air because it is one of the most commonly installed fans and therefore had lots of information around installing and maintaining it. Not only this, but the Maxx Air fan is capable of reversing the fans direction which is very useful. We went for the 350 model which meant that the hole we needed to cut was 350mm x 350mm. This actual measurement wasn't used in our case as we followed the templates that we created, but it is worth determining which size you need. 

If space is limited, like it is on Faith's roof, you might want to get the smaller 350 model, but if space isn't a concern and you want slightly more throughput then the slightly larger 400mm option might be for you.

Why do I need a camper van ventilation fan?

As we mentioned before, the main reason you need a camper ventilation fan is to circulate the air around your vehicle. This will remove the stale moist air and replenish it with fresh dry air. In doing so you will prolong the life of your camper, prevent rot, decay and also the horrible musty air that occurs when windows are closed for too long. Not to mention the fact that you can extract the heat from cooking much easier and not smoke out the camper!

Creating a template for the fan

The first step is to create a wooden frame that the fan will sit into. This means that when we screw the fan through the metal shell of the van, the screws will have somewhere to screw into and secure the fan in place. This will allow the fan to essentially squeeze the metal shell of the van ensuring that it never blows off! With the Maxx Air fan there are two main pieces, the cover and the flange, which for this post we are going to refer to as the 'mounting frame' that the fan sits into. The cover piece is a lot taller than the mounting frame and has four screw holes (it's used for the finishing touches when installed), whereas the mounting frame has sixteen screw holes instead. We want to use the mounting frame to create our wooden frame.

We began this process by grabbing our timber battens, which I believe was a piece of 2" x 2" untreated timber. We then marked the length of mounting frame onto this piece of wood and cut the right length. You want to be creating the frame on the side of the mounting frame that has the ridges in (as seen below) Once we had the first length cut we were able to use it as a template to get one more of the same length. Then we place these two pieces either side of the mounting flange to get the length of the wood that would go between them. We cut and dry fitted these around the fan casing.

Once this was completed we next sanded down each pieces and predrilled some holes through each side of the long pieces. We used a drill bit that was slightly bigger than the thread of the screws and countersunk the hole so that the screw would fit flush. This means that the screw can slide through the first piece of wood but screw into the second, really squeezing the gap between them allowing the glue to set and help the join.

After this we applied some wood glue to the joining faces, placed the frame around the mounting frame and screwed the wooden frame together. Once the frame was screwed together we removed it from the mounting plate to dry separately and ensured there was no glue squeeze out on the frame that we wouldn't want. We also marked the top and the bottom of the fan so that we knew the orientation that it fitted onto the mounting plate. Unfortunately, at this point we were not treating all the wood that was going into the van, however, if we were to do this again we would've treated the frame with one coat of the danish oil top coat we have been using for everything else.

IMPORTANT: I'm going to keep repeating this throughout these blogs, DO NOT use pre treated timber inside the van, they can release gasses that aren't good for you and being inside a small container will just enhance that! Kiln dried timber should be the only thing used that you can then treat yourself with something like danish oil.

Marking and cutting the hole

The next step was to cut the hole in the roof of the van for the fan to sit into. To do this we followed a very similar process to the window installation, if you haven't you can read about that here. We will briefly explain the steps so that you can follow along here too.

We created a cardboard template of the area that we needed to cut. The area in this case, is the inside ring of the mounting plate on the ridgy side of the mounting plate. This template is much easier to create tan the window as you can simply draw on the outside of the frame onto some cardboard and cut it out. Once you have a template it is worth double checking that it is the right size. To be completely transparent, we somehow made the mistake of making it far too small (the left image)! The correct size is on the right / below on mobile. It pays to measure twice and cut once, especially when dealing with huge holes in the roof...

We then need to determine where we want the fan to sit on the roof, so it's time to make your way up there, however that may be. Please be extremely careful if you are going to be climbing on top of the van as you don't want to injure yourself or dent the roof! It is worth using a large piece of wood to sit upon to distribute your weight out, otherwise it might end up costing you to get the roof fixed... The best way to prevent any damage is with a raised platform over the van but that is not in everyone's shed, especially not ours!

How do I know where to put my camper van's fan?

The best way it to take the template we just created and play around with different positions, ensure that you take into account the other appliances you are having (such as solar panels). You also need to bear in mind that the fan will overhang the template by an extra 20cm or so and needs to be placed with that pointing towards the back of the van. In our case, we knew we were going to have the Maxx Air fan and two solar panels. As we didn't have the solar panels, and Faith is one of the shortest lengths of van you can get, we took the measurements four times, yes four times, to ensure that we were able to fit all of them onto the van without anything hanging over the edges.

We tried our fan in a few different places, one of which was on the front curved section of the van, however due to the large curve (shown below) we decided to avoid this so the fan could be on a flat surface. Our next choice was to get the fan as close to the horizontal support beams in the van, giving us just enough room for the solar panels to fit.

Once we were happy with its position, we took the template inside, found the horizontal support beam and taped the template to the ceiling. We made sure to align the fan in the centre of the van by measuring the width of the van, dividing by 2 and taping the template, we then double checked again by measuring the distance from the edge of each side of the van to the edge of the template. If these two values are the same then the template is centered. We made sure that the template AND the wooden frame would fit next to the support beam without having to cut through it. We did not want to cut the beam and cause any structural changes so got as close to without causing harm.

With our centered template, in the correct position, it was time to cut the hole. Like with the window we drilled two holes through the template and through the van's ceiling (scary!). We also took a picture of the template to remember which way it was taped to the ceiling. We then made our way to the roof of the van, used our two drill bits as markers for where the template needed to sit. We roughly lined up the template so we could tape the area. Then aligned the template in the correct direction (using the picture to ensure that if the writing was facing down, it was still facing down on the roof) and marked out our lines.

Top tip: Lay down some duct tape around where you will be cutting to prevent scratches on the paint work and make it easier to see the line you should cut.

You are going to be going up and down a lot during this process so having two of you is very useful.

We started by trimming the Maxx Air fan's box so that we could stick it to the ceiling around where we were going to be cutting. This would ensure that any metal shavings would be caught inside the van preventing them from causing unwanted rust spots. With that secured, we drilled four holes (marked red) large enough for the jigsaw to fit into on each of the corners of the hole we were cutting, (I only have an image from the outside so apologies for skipping ahead for this photo).

Kez was on the inside and was just double checking that we were coming through the van where we expected. From here, it was a simply process of following the lines we had drawn with the jigsaw. As the inside line of the marker was the template size, we aimed to cut in-between so that it was going to be easier to fit the fan than the window was!

Top tip: Leave a small tab of metal between the van and the hole you are working your way towards (marked in blue). That way the metal will flap far less, then when you have done all four sides you can simply tape down some of the gaps, jigsaw the tabs off and take the metal out.

We then filed all the edges so that we could test fit the mounting frame into the hole. If it first nicely, make sure there are no rough edges that will cut into the plastic. Otherwise, make any minor adjustments (which hopefully shouldn't be many!) until it fits in nicely. Brush any of the shavings that are on the roof through the hole and into the cardboard box that you should now be able to see. You can then remove the cardboard box and see each other for the first time!

Mastic and install the plastic casing

Next up, we painted the cut edges with some top coat Hammerite to protect from rust, we left this to dry for about an hour, so it is worth doing this on a nice sunny day so no rain leaks into the holes if you are doing this outside!

Now, the keen eyed among you might've noticed that when you placed the mounting frame into the hole there might've been some gaps where the ribs of the van go from low to high points. This isn't ideal as it would leave a huge gap for rain water to fall into! Therefore, we need to apply some mastic in between the gaps to level out the entire surface. What is mastic you may ask? It's almost a play dough style consistency that can be moulded to fit onto any surface, it is also very squishy which gives an extra layer of protection from outside surface water!

We rolled the mastic out on the outer edge (on the roof) of the hole so that we had a nice flat and flush surface level. We made sure to apply this right to the edge of where the flange is going to come so that it wouldn't stick out past this when installed. We ended up doing ours a little bit too small so had to squeeze some mastic underneath where each of the screws would go to give them some support. 

Top tip: We ripped the mastic to fit in the low spots of the van and then applied one constant layer of mastic around the entire perimeter, over the now filled low spots and with one layer over the high spots. This allows one flush layer over the entirety of the contact surface.

With the mastic on and the area being level it was time to install the fan. We pushed the mounting frame through the van and placed the wooden template underneath around the framing, using the marking we did at the beginning to ensure that it was facing the right way. You want to ensure that the metal tabs on the mounting frame are on the outside edge, this way the fan will be orientated correctly when in place. We then applied a little bit of Sikkaflex to the wooden frame and clamped both itself and the mounting frame together so that we didn't need to keep hold of it. We used a few scrap offcuts to help our clamps with adding pressure to the wood, but some bigger clamps would definitely be easier!

Now we can screw the frame through the van and into the wooden frame. On our model (the 350x350mm version) there are 16 holes for the screws to go into, so we dug through the packaging and found the only set of screws that had 16 of them so we knew we were using the right set, there is another pack in there for securing the fan to the mounting frame.

We found a metal drill bit that was slightly larger than the threads of the screws but could still fit into the mounting frame holes and drilled through each of the holes and slightly into the wooden frame, we first of all did this on just four corners. We made sure to have one of us holding the wooden frame to prevent it from moving and secured the fan in each of the corners. To prevent leaks and water ingress, we applied a little bit of Sikkaflex to each of the holes BEFORE screwing the screw in. This means that the thread and the join would be protected with Sikkaflex. With the four corners done we could remove our clamps and complete the rest of the holes. 

Top tip: Take it slow with the drill bits, you will find that some mastic wants to get pulled around so just be gentle and refill any area that might come loose. We also snapped two drill bits during this process as they were so small and fragile, so take your time!

We also ended up having two screws that for some reason just would not go through, this could've been from not going through with the drill or hitting some tough knots in the wood. We decided not to push it any further so left these two, leaving up with 14 holes, which we were more than confident would be enough!

Fitting the fan

Finally, it's time to fit the fan and cover up the massive hole we have in the roof! We wanted to test fit the fan to make sure that it fitted properly as we were slightly worried we might've misshaped the mounting frame due to not being fully flat on the roof. We pushed the fan in and were pleased to see that it fitted just right, big smiles all round! We took the fan back out and applied a bit of Sikkaflex to the top of each of the screw heads, with a bit of water on your fingertip you can push the Sikkaflex to any shape and make it look a little bit neater on each one. We also taped some masking tape around the edge of the fan, Sikkalfex'd around the edge, smoothed them out with some silicone shapers and took of the tape. This made sure that no water would get into any of the screw holes or underneath the edges of the fan.

P.s. Sorry about my finger tip over the camera 😳.

We had been outside for about 3 hours at this point and wanted to get it finished to went straight ahead with screwing in the fan. In hindsight we should've left this and let the silicone dry before attempting to install, it kept getting stuck to us whilst we were up there!

Start by opening the fan up to its open position by twisting the manual handle on the fan and then place it back into the mounting frame. There are four screws that we need to screw into the fan. The screws are quite difficult to line up through the mounting frame and into the fan, I found a slight ledge on the side of the fan that I could use to push it down and line up the screws. You want to be very careful not to be pressing on the hood of the fan itself too much, you don't want to damage any of the motors inside the fan with excessive force. That's why the ledge of the fan is much better as it's directly attached to the plastic.

Once two screws were in, we did one on each side first, the last ones went in slightly easier, we worked our way from back to front but in hindsight we think starting with the front screws (the actual front of the van) would've been easier.

Leak testing

The final step before you can call this job complete is leak testing. Much like we did with the window installation on the van we want to directly spray the area with a hose and ensure that no areas inside the van are wet. We can verify this using a piece of paper and sliding it around the van and the wooden frame. If any part of the paper comes out wet you know that you have a leak that needs addressing.

We learnt a few lessons from this project which included the following.

Accounting for the extra 20.8cm of overhang that the Maxx Air fan has when calculating real estate on the roof for extra appliances such as solar panels.

Next time we would also definitely let the silicone dry on the mounting frame before trying to install the fan, our hands kept slipping whilst we were trying to get the four screws in. This was very frustrating and also extremely messy!

The final lesson would be to get a ladder big enough to work on top of the van, we were having to climb up a small ladder and manoeuvre onto the top of the van which isn't very safe.