Dometic Vent Roof Cap Modification

As mentioned in the blog, here it comes another forced modification of a very common product: the Dometic Vent Roof Cap part N: 3311246.000. In a nutshell, this product has 3 faults in the actual design.. They are all not easy to spot, unless you are willing to spend a bit of time under the vent with the fridge removed in a rainy day.

Let me be clear here, the actual cap does NOT leak water, but because of the design, given specific circumstances, like strong wind and heavy rain (like most of the storm in QLD) will allow water to enter your fridge compartment. How? Keep reading..

As I was working on my Dometic fridge to improve its Tropical Rating performance, it just happened to find myself under the fridge vent mounted into the roof in a middle of a storm. Imagine my surprise as I looked up when realising that I was getting drops of water in my face 😮. How can it be? It only took a couple of minutes of rain to actually see the problem.

The Dometic Vent roof base, that I use in my conversion, it is designed to fit in conventional motorhome where the roof thickness seems to be around the 30-40 mm. Gigi, on the other hand, has a roof thickness of 65 mm, so when I installed the vent roof base I had to attach myself to the outside of the roof instead of coming out of the roof with the plastic vent mounted from the inside. While this is obviously not Dometic fault, it did manage to exacerbate the original faulty design.

Lets look first at the not so obvious problem number one. In the first picture is the Dometic vent roof cap. Now beside the fact that this product is described as a kit and yet it doesn’t come with the correct stainless steel screw for a proper installation, it has another major problem. If you look closely to the cap you can clearly see that the centre and most of the cap is actually concave. I didn’t pay much attention to that feature when I first purchase it or either when I installed, as I presumed that the cap would have been tested in all sort of weather. Silly me for thinking that..

What does happen when the rain is heavy is that the splash bounces on the roof and then in an upward direction, hits the concave part of the cap through the gaps on the sides of the cap. As the splash continues to accumulate, it eventually does form a much larger heavy drop because of the concave design right in the middle of the cap (the lowest point obviously). And then it drops inside your RV. Simple as that!

In the second picture, you can see two dots in the centre of the cap. That’s the lowest point and that’s where the drops of water will form. At first, I thought that because of the large gap between the bottom of the cap and the roof, that was where most of the splash was happening, but I was wrong. While the excessive gap did not really help, the major splash does occur in the design fault n.2 where the cap has the 45° angle in front of the gaps. When it rains at an angle, it has the same effect as water hitting the roof at a perfect 90° angle. And here we also have problem n.3..

The vent roof base has two  wingtip one on each side that are supposed to stop water splashing inside the cap. Problem is that they are too short, barely reaching just above the bottom part of the gaps in the cap, leaving a huge gap above for easy access of water splashing on the 45° angled side of the cap itself.

In the next three pictures you can see my attempt to mitigate the problem of the water splashing on both the roof and the angled part of the cap. I first lowered the cap 3 cm towards the roof to eliminate the difference from the conventional roof mount. Then quickly realising that the majority of the splash was actually coming from the angled part of the cap, I decided to add two extra pieces of plastic to completely eliminate the water hitting the angled sides. That, to an extent did work, but in very windy situation, or driving while raining, I’m sure the problem would still persist and frankly, I wasn’t happy about either the look of it or the fact that if I did use a garden hose to wash the roof, because of the location of the wingtip, I would end up having water entering and hitting the top of the fridge, where all the electrical components are…

Sorry Dometic but this cap is a complete failure! Too many faults in the design to a point that I start to look around and found that another company does make the perfect solution. The Camco Fridge vent roof cap, specifically designed for direct replacement of the Dometic and Norcold roof bases.

Now, why would a company feel the need to make a replacement part to fit other company products, if such parts were working correctly? Well, as I and possibly lots of other consumers already found out, they don’t! So bless Camco for coming to the rescue with this great but above all, perfectly designed replacement part. Lets see what they have done:

The front of the cap is design to push water away (like when you drive in the rain), the angled side are completely gone, eliminating the change of water splashing on it and entering the vehicle. The top is also flat and not concave like the Dometic, so if water gets there it will not run into the middle and again, come inside the vehicle.

But perhaps the most intelligent change in the design was to attach the wingtip to the top of the cap instead of the bottom of the base. What that does is completely prevent water coming from any direction or angle to again, entering the vehicle. The cap is much larger than the base and that also helps to prevent splash of water entering either from the front or the back of the cap where there are no wingtips. Finally the back of the cap is flat at the back as, it doesn’t need to be aerodynamic like the front, making the whole cap very pleasing to the eyes while doing an excellent job at keeping water out..

I would like to also mention that it only cost about ten dollar more than the original piece of shite Dometic makes and while not been advertised as a kit, it does come with all hardware require to make the conversion, that is really a 3 minutes job.

Just remember that it is about 15-20 cm longer than the Dometic (I didn’t really measure it) but the dimension are specified on the website.

Camco also does sell an extra package containing a solar panel and a little fan, that can be added to the Camco cap (you can actually add two) and enhance your fridge cooling capabilities even further. Now, based on my previous experience with very small solar panel, they are just next to useless, but it is nice to see that they are working and trying to make things better for their customers…

Thank you Camco for coming to the rescue..