Replacing a Remis roof vent with a fan vent

I’ve replaced the Remis Vista 400x400 roof vent in the galley area of our Kemerton with a Maxxfan Delux fan roof vent and having had the experience of installing and using it, thought this maybe of interest to others. 

The reason for making the change was to extract damp air from inside the van when weather conditions prevent doors, windows or roof vents being opened.  The experience of a wet September/October last year driving the NC500 and touring on Orkney got us thinking about how to deal with steam produced during cooking and damp air introduced by wet foul-weather gear.  The conditions up there were wet and windy much of the time, so we had to batten down the hatches and accept misted-up windows.

I’ve since looked at various fan options that are able to be operated whatever the weather and which are powerful enough to change the volume of air inside the van reasonably quickly.  The Dometic fan above the hob, as fitted by AS, does not vent to the outside and only recirculates, using filters to absorb cooking smells and grease.  I considered changing this for an extractor fan unit in the same location but couldn’t find an easy way to route the 5” diameter vent trunking to a roof cowl. It would have required doing away with the microwave, making changes to cabinetry and cutting a new hole in the roof, which I judged to be too invasive.

Discounting this solution I then looked at adding a supplementary fan to the Remis roof vent in the galley area.  The vent is above the hob so is well placed to remove cooking steam and odours, as well as being towards the rear of the van where the shower is and where we hang wet clothing and footwear.  Various supplementary fan options are available from different manufacturers but they all require the roof vent being open during their operation, and are therefore limited to fair weather.  Moreover none of them are very powerful in exchanging a volume of air.

With some more internet searching I found the Maxxfan roof vent, a US product from Maxxair but now widely available in UK.  Able to operate in rain, using a 12V, 10-speed fan powerful enough to exchange the air volume in the van approximately once every minute, it offered everything we were looking for.  It is also sized to fit the same roof aperture as the existing Remis Vista, making installation very straightforward.  It doesn’t come cheap at around £300 but at least I could fit it myself.

The first task was to remove the Remis roof vent.  The interior trim, blind and insect screen (a single, integrated assembly) had to be removed first and in this I was guided by helpful advice from forum members in the following thread: [You must be registered and logged in to see this link.]

Once the interior assembly had been removed and the 6 “ball & socket” fixings for the vent unscrewed, attention could shift to the exterior.  Using a thin-bladed kitchen knife, I cut through the sealant used to stick the base of the Remis to the interface plate on top of the roof.  This plate is matched to the corrugated profile of the steel roof and provides a flat, smooth surface onto which the Remis is fixed.  The plate remained in place ready for the Maxxfan and once the complete Remis roof vent was removed I cleaned up the face of the plate and removed all traces of sealant using methylated spirit.

With a clean, flat face for mounting the Maxxfan onto, I found that the new fan unit sat perfectly onto the plate and fitted into the aperture with virtually no side-to-side or front-to-back play.  I used clear Sikaflex EBT+ to stick the Maxxfan onto the interface plate.  It’s a cost-effective sealant and, most importantly, stays flexible once cured.  The Maxxfan comes with stainless steel self tapping screws to fix its base onto the interface plate and I used these as well, pre-drilling the interface plate to accept them and then applying Sikaflex to the heads once screwed in.  The instructions supplied by Maxxair were excellent and the unit feels well engineered.  

The interior fitting details were more exacting, but only because I wanted to retain the original Remis concertina blind, insect screen and trim assembly, rather than use the inferior plain trim supplied with the Maxxfan.  Maxxair supply a blind at an additional cost but it looks flimsy, doesn’t have an insect screen and just wasn’t good value for money.  I also wanted to keep the Remis assembly in order to preserve the factory fitted look of the interior and coordinate with the larger Remis “windup” opening vent at the front of the van.  The Remis assembly needed a bit of fettling to get it to fit with the Maxxfan but once in place and secured with the 6 ball & socket fixings fitted in their original locations, it all looked good and worked correctly.  The blind and insect screen operate as previously and, visually, it doesn’t stand out that anything has changed.

The electrical installation was straightforward, requiring only a 12V supply.  I “fished” the cable from the Maxxfan above the ceiling lining and into the cabinetry that contains the microwave.  I’d already removed the latter, which in turn requires prior removal of the hob fan to access the microwave fixing screws.  I jointed the 12V supply cable into that of the Dometic hob fan using a connector block.  This is on the lighting circuit and with some measurements of maximum current drawn I confirmed that the fuse is adequately rated to accept the additional load from the Maxxfan when running at full tilt.

The Maxxfan is easy to operate, either at the fan itself or using the remote control.  When the fan is switched on a servo motor raises the roof vent assembly which exposes the rear-facing vent and places it in the vertical plane.  This is why it can be used in the rain, assuming the latter isn’t driving into the face of the vent.  So long as the van is pitched with its rear facing away from the prevailing weather, all will be good and the fan can be used in most conditions.  

So far we’ve only used the Maxxfan in it’s extraction mode, but the fan direction can be reversed at the press of a button to draw air into the van.  We had something similar on the Autotrail van we rented in New Zealand earlier this year and it really helped to keep the interior at a comfortable temperature, using far less power than an AC unit would.

Most importantly for us, we can prevent the windows misting up, and exhaust damp air.  Cooking smells and steam from the hob and oven are also extracted rapidly.  We’re still experimenting with optimum fan speeds (given there are 10 to choose from) and a lot depends on how much air is entering the van through other holes, such as gas drop-outs, grills and vents. So far our experience with it has been in winter, with doors and windows closed, but initial impressions are very good.

The Maxxfan comes in 3 colour options for its roof vent.  We chose the clear option in order to maximise the passage of natural light and we purchased it from Roadpro, who gave us the best price at the time.  Different solutions lend themselves to different vans but for the Kemerton and for our mode of using it, in all weathers throughout the year, in UK and in mainland Europe, we judged the Maxxfan to be by far the right solution.  It’s not much more expensive than the cost of a proper hob extraction fan such as the Dometic CK400 but is more powerful, provides more capability (including the option to draw air into the van) and in our case was much cheaper to install.


Tim


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May I congratulate you on your most detailed explanation on the fitment of the Maxxfan You have provided the confidence for other members to do the same, perhaps even myself. 

Given the current extremely hot weather I thought it timely to give an update on our experience of using the Maxxair roof fan.

We were away in the van this week with outside temperatures up to 33C in the daytime and mid-20’s at night. During the daytime, with the van parked up and left unattended we put the Maxxair on its exhaust setting to help pull heat out of the van. More significant though was the nighttime experience, with the fan flow reversed to pull the cooler night air into the van and establish an airflow across the sleeping area. Our temperature sensors showed the van interior to be 5C lower than the outside. We tried various fan speeds and settled on 30% of max speed which was quiet enough not to disturb sleep.

We fitted the fan principally to extract damp air and cooking steam, to prevent condensation build-up in colder weather but using it in a different way during very hot weather has been a revelation this week. We both agreed it’s the most effective mod we’ve made to the van, and we’ve made quite a few.

Tim

Excellent mod. Is that the original Remis frame sitting below the vent or a very similar one supplied with the fan. Getting 12V there is certainly the biggest challenge! Can't remember whether my Freshjet has 12V as well as 240V or just the latter.

It’s the original Remis interior frame and blind assembly. The internal corners on the plastic frame of the Remis needed a small amount of fettling to mate with the Maxxair frame but it was worth the effort and doesn’t show. The interior frame supplied with the Maxxair is inferior by comparison and the indented outline of the larger Remis frame would have been visible on the roof lining.

I was fortunate to have a 12V feed nearby and only had to fish the cable through the roof lining for about 300mm.

Tim

Just had a Maxxfan fitted last week by Roadpro. On Kingham they took power from the tv socket plugs in the wardrobe. Opted for the Maxxfan blinds which to me seem as robust as originals. Slight marking of headlining visible at present but not really noticeable. Very effective in operation all way through from quiet to noisy, you just have to choose/ balance your preferences. Have kept old roof light just in case
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A superb bit of kit. Fitted one for this year and it has been superb at keeping us cool and comfortable in France for the past month. It was very easy to fit to replace the difficult to use Remis by the cooker ( which can't be used when it is raining). Used almost exclusively on extract with a window slightly open to allow cooler air in

Kemerton-bath wrote: The Remis assembly needed a bit of fettling to get it to fit with the Maxxfan but once in place and secured with the 6 ball & socket fixings fitted in their original locations, it all looked good

Tim - thanks for the excellent detailed write up.

Apols for digging up an old thread, but I’ve just ordered the fan and had two questions for you, that I think other readers might be interested in, if you don’t mind:

1. What was the ‘fettling’ required? I really want to put the existing Remis trim/blind(s) back, so keen to learn.

2. I’ll be mounting on the flat roof of a Neuvo. I’d read a write-up of someone doing similar who used W4 Mastic Sealing Strip AND the Sikaflex. This seems a bit OTT to me, but wanted to check you were happy with the seal the Sika gave still?

Many thanks,
Heeb

I fitted the Maxxfan to my Nuevo but did not use the Remis blind which for my swap is not necessary. I took the 12V feed from the ceiling light near the bathroom door. I was able to feed a length of stiff wire (an opened out wire coat hanger) from the corner of the Remis aperture across to the hole where the wires for that light come through the ceiling panel and then pull through a suitable 2 core flex. The Maxxfan has its own excellent and stout fly screen which is easy to clean when necessary. Even though I used the clear version of the vent the fan is some way from the beds so light penetrating at night is not a problem. I do need to find a source for about a foot of the two part ceiling panel joint cover strip either side of the vent aperture. The existing piece that fitted the old gap between Remis and the bathroom wall is long enough to cut down for the new gap on the other side if I can buy a new length for the bathroom side. We have found that we almost invariably use extract - between 50% and 70% when cooking and just 10% which is totally silent at night. I used the sealant strip provided but added a small bead of Sikaflex outside that for added security.

Thanks Ron! Didn’t realise it came with a sealant strip too!

I’ve got my eye on the same light fitting to provide a feed. Could I ask what connectors you used to splice in? I think I’ve some somewhere from doing garden lighting, but wanted to check before I go hunting!

Think I’ll have a look at the supplied trim then, before I start too much fettling!

Thnx,
Heev

It's over a year since I did the job but I think that I simply used a small connector block. The other possibility is that I soldered the wires and wrapped in insulation tape. In either case the joints can be stuffed under the board that has the LEDs mounted on it. AS don't leave much spare wire in the connections so that may dictate how you make the connections. A nice touch is that the heads of the flange trim securing screws supplied with the Maxxfan are painted white to match the flange trim. If you find a source for the ceiling joint cover strip please let me know

Heeb, am away at present but will respond to your Q’s in a day or so.

Tim

Heeb,

Pleased you found my original post helpful. In response to your questions, I’ll answer the easy one first, regarding sealant.  The Maxxfan didn’t come with a sealant strip supplied but maybe they now do, so the Sikaflex EBT+ sealant was the sole means of achieving watertight integrity. There was no water ingress in the 3 years the Maxx was fitted to our previous Kemerton, and before we traded in the van earlier this year I removed it and re-fitted the original Remis vent that I’d kept. The sealant had remained flexible and was easy to cut through.  I cleaned up the Maxx to be like new and have recently fitted it in our current Kemerton XL, again replacing the Remis Vista. I kept to the same installation procedure, retaining the Remis interior frame assembly, and with the benefit of learning it took less time than previously.

Answering your question about the fettling requires more detail to make any sense. The fettling required is solely to the upstands of the Remis interior frame assembly and no changes were needed to the Maxxfan assembly. To clarify what I mean by “upstands”, if you lay the Remis assembly on a flat surface, such that it’s inside face (ie that which mates with the underside of the exterior assembly) is pointing upwards, you’ll see a square shape made of thin plastic walls in the vertical plane. I call these the upstands. Two of the opposing upstands return around the adjacent sides to make the corners and those returns each have 2 plastic tabs to fix the corners together. These returns create a double layer of plastic which has to dealt with to allow mating with the Maxx, more of which shortly.

I found that when the Remis assembly is offered up to the Maxx these upstands almost fit around the square baseplate of the Maxx. By “baseplate” I mean the plate that carries the fan screen and the controls. If you study the 3rd picture in my original post you’ll see a gap around the baseplate, outboard of which is a further plastic “downstand”. This gap is wide enough to accommodate the upstands of the Remis interior assembly once the latter has been fettled. I found it would fit on 3 sides but the 4th was impossible to engage in this gap as there’s a slight difference in size between the Maxx and the Remis assemblies. Hardly surprising as they’re not designed to mate.

To get the 4th side to fit I disengaged the 2 plastic tabs on each corner of the Remis upstands. With the corners unfixed the upstands can splay outwards slightly, enough to enable all 4 sides to fit into the gap around the Maxx’s baseplate.  However the Remis assembly doesn’t push upwards far enough for the 6 ball & socket Remis couplings to engage. This is because the corners of the Remis upstands foul with the corners of the Maxx downstands. The fouling is caused by the double thickness of plastic at the corner returns I mentioned earlier. To resolve this I cut away approx 15mm of the uppermost piece of plastic on each of the Remis’s corner returns, thereby removing one layer of plastic in those corner areas. I used wire snips to cut the plastic, which was fairly soft and didn’t shatter. Once I’d made all these changes I found the two assemblies mated successfully and the ball-&-socket fixings engaged very satisfyingly.

In the first 3 pictures below you can see how the Remis upstages are slightly splayed, the dis-engaged corner tabs, and the small gaps where I cut away the corner returns. Although these features are clear to see in the close-up pictures (deliberately so for illustration) they aren’t obvious in reality and do not detract from the overall finish. Equally they weren't obvious when I came to refit the Remis vent in the previous van.

The procedure is clearly not without risk of damage to the Remis assembly, but I’ve now performed it twice in two different vans without a hitch. I decided to go the extra mile and fit the Remis screen in order to preserve the original interior look, and to avoid seeing the marks on the head lining that would have been visible if I’d used the smaller sized interior screen supplied with the Maxx. 

In the 4th picture below you’ll see that the circular screen of the Maxxfan is a little larger in diameter than one side of the aperture in the Remis. This makes for a slightly awkward removal of the circular Maxx screen when it and the fan blades needs to be removed for periodic cleaning. However this is only once a year in our experience and there’s enough flex in both assemblies to allow careful removal of the circular screen and fan blade. Final picture shows the Maxx on the roof of the Kemerton XL and how well it cleaned up after 3 years of use on the 6m Kemerton. 

We’ve recently been RV touring in the US and noticed that the Maxxfan is used widely over there. I’ve seen more of them here as well in the past couple of years, particularly on DIY van conversions.

Hope this helps,

Tim

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Excellent description Tim. As I have said I did not refit the Remis blind and surround and it had left no marks on the ceiling. You don't have the two part joint cover strips that are on my Nuevo and which have to be extended to give a neat finish to a it to the smaller Maxxfan internal trim.

Thanks Ron, ah of course, you have a different ceiling construction in a coachbuilt. You've probably considered it but I wonder if a building-plastics supplier might have something suitable for your joint cover requirement. uPVC window installations require all sorts of profiles to hide gaps.

Tim

I just haven't made the time to search. Ithe actual joint between the ceiling vinyl coated boards is very tight so it doesn't show much. It's a very shallow profile joint cover which is two part - a flat section stapled to the ceiling with a raised lip onto which a very shallow elliptical section clips. I keep meaning to look on the web or to pop in to a caravan dealer when passing. Of course Best also has a Nuevo but his ceiling construction may be different on a newer van. I remember Mark being very concerned around 2016 when the internal walls were changing from boards with the stick on strip that doesn't to a much bigger one piece moulding. 🥺

Tim,
Can’t thank you enough for taking the time to provide so much detail.

I’m going to attack the replacement next week, monsoon weather permitting, but I suspect you’ve saved me hours of frustration.

Thnx,
Heeb

You’re very welcome, hope the installation works out well for you.

Tim

Job Done!

Many thanks again to all on this thread, but particularly Tim/Kemerton-Bath.

Couple of observations from my installation.

- I couldn’t believe at first how difficult it is to get the old mastic off. Found a YouTube video from Practical Motorhome that showed how much welly was required! Their tip of putting in increasing sizes of wedges in once you got a corner loose really helped.

- I used the Screwfix Sealant Remover to get the last of the old sealant off. Worked really well.

- I used the metal coat hanger technique to get thru the insulation to the nearest light fitting. Taped the cable on to it and pulled back through. Used 3 pole(?) Wago clips to splice in, but really pretty tight.

- I really struggled to get fan body holes to line up with the metal brackets on the roof flange. The fan just wouldn’t go down far enough into the flange and there didn’t seem to be any blockers. Eventually I managed to force one down enough to get a smidgen of alignment then got a screw in a bit. Went round the rest doing the same. Perhaps this is deliberate for a snug fit?

- even with faithfully following the fettling instructions, I still struggled to get the Remis base to mate in. I eventually got there with quite a bit of force (I suspect the Neuvo roof is likely thinner than Tim’s). My biggest concern here is that ‘knobs’ are not particularly tightly mounted. Obviously with original Remis set up there is a second screw clamping onto the outer casing. They mounts also have little teeth - no doubt to grip onto a vinyl/carpet ceiling - but that part of my roof is hard, so the teeth just prevent smooth contact. My opening didn’t have any wooden reinforcement, so the screws do have a tendency to spin/come loose. I tried to use a slightly thicker screw, but didn’t make much difference.

So, all in all, I’m relatively happy. The fan seems to be doing its job and the finish is good. I’m just worried that the first seriously bouncy road and the screws holding the mount on May detach. A test drive is required for sure.

(If anyone knows a better way of fixing to this type of roof, let me know! If disaster strikes, the plan for now would be to put in a wooden frame.

Rgds,
Heeb

Excellent, glad it went reasonably well. The roof of a panel van can certainly handle more force than I imagine a coach built roof can. In my case the roof opening sits across one of the ribs of the van, so is a bit stronger than it might otherwise be. I don’t know the construction of your roof, but wonder whether the fastening clips for self tappers, used widely in the automotive industry might be an option, such as those in the link below.

Tim

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Glad it wen well, Been. Curiously my Remis did have wood framing around the aperture but, as you say, the thickness of the roof could well be less than that found by Tim. I concluded that trying to make the old Remix blind unit fit neatly and fasten securely was fraught with difficulty so chickened out - but I must get round to getting some of that cover trim  I'm sure that any caravan repair shop would stock it!
You will find the new fan a brilliant mod.