Winter brings many RV owners a bit of slack time. Time to make plans for the next season’s outings. Time to catch up on a little maintenance. And it could be time for an RV improvement project or two that can make the next season’s travels even more enjoyable. Here’s a potential project that won’t take too much time, but will pay big dividends on your RV outings.
Having a power roof vent can make a big difference in seasonal comfort. We’re stepping beyond the “power fan” in the bathroom, to one of those with big blades, a MaxxFan as an example. Putting in a new power roof vent is an easy project, one most any RVer can handle. We installed a new MaxxFan a few months ago, and we’ll share both our installation experiences, and our findings about how well the fan works in the real world.
Installation Considerations
For this project we’re not talking about a bathroom ventilator fan. The MaxxFan is a big bladed, powerful device that will move a huge volume of air. We found the best place for ours was over the dinette area in our truck camper. This is the locus of our inside activities—eating for sure, but card playing and other family activities are central to this area.
For a power vent to work, you’ve got to have power to it. If you’re replacing a simple vent fan with a new one, you’ll have “juice” right where you need it. We won’t go into plumbing in wiring for a roof vent that has no existing power available. It can be done, but can get complicated. Before starting with an installation, make sure the power to the wires feeding the fan is dead. Pull the fuse that serves the circuit, or if you’re not sure of it, disconnect the house battery and unplug shore power.
Outs and Ins
First, take out the old fan. From the roof level, use a putty knife (or carefully use a utility knife) to peel any sealant away from the existing mounting screws. Use the putty knife to also score around any old sealant that’s sticking down to the vent. Remove the screws, and carefully pry up on the old fan unit to avoid damaging the roof. Using your putty knife, clean down to the roofing material an area 2 inches away from the edges of the roof vent hole. Disconnect (or cut) the wires running to the old fan, making a note of polarity.
Next it’s time to prep the new fan for installation. Strip back the insulation from the RV electrical wires (and the fan wires if needed) and using appropriate connectors (we like crimp style) mate the fan wires to the RV wiring, observing polarity.
Next, lay down a layer of butyl tape on the inside flange of the new unit. Press it down firmly all around the flange before pulling the paper away from the tape. We’ve always been of the school that says, “If one layer is good, two must be better.” However on our most recent installation with a new roof deck and new roofing material, we opted to try just one layer of butyl tape.
Why butyl tape? Many RV roofs are EPDM rubber, and other types of putty can damage the material. If in doubt, always check with your roof manufacturer for advice. Our camper roof is a special composite material, and we could use just about anything for a sealant. However, we’ve found butyl has a longer life than standard putty tapes, particularly when dealing with a desert climate.
Lay the fan into the opening, making sure the fan hinge is pointing to the forward end of the rig; carefully center the unit in the opening, too. It’s OK to let the wires dangle down into the RV, just make sure they don’t get pinched between the vent and the roof. Start off by setting your cordless drill to about half-clutch and insert one of the flange mounting screws. Adjust the clutch setting so that the flange is thoroughly set into the butyl tape, but not so tight that you might damage the flange. Our “one layer” of tape squished out from the side of the flange, assuring us that a single layer was sufficient. If it hadn’t squirted, we would have pulled the fan back up and laid another layer of butyl atop the first one and started again.
With all screws secured, run the edge of the putty knife along the flange edge, cutting off the excess squished out butyl tape. Now lay a bead of caulk along the outside edge of the fan flange. Be careful to use a sealant that’s appropriate for both the vent fan material and your roofing. If you’re dealing with an EPDM rubber roof, you’re probably safest with Dicor lap cement, but double-check the specs from the fan manufacturer. Our new fan specifically ruled out a lot of different solvents, including acetone, which we might have used otherwise in cleaning up the surface of the roof. Finally, the MaxxAir folks recommended a dab of sealant over the top of each of the mounting screws. We don’t particularly favor that, especially since the mounting screws provided were Phillips type. Next time we have to pull that roof vent, there’ll be all kinds of fun cleaning the sealant out of the screw slots!
Inside Work
Once the outside work is done, you’ll need to head inside to put in the new garnish ring (sounds like something from an all-you-can-eat bar). Since your ceiling-to-roof height will probably vary from corner to corner, you’ll need to cut the garnish ring to meet the need. We grabbed an adjustable carpenter’s square to help us. Sticking the end of the square’s rule up beside the newly installed fan, we loosened the arm and pushed it up to the ceiling. Then we tightened the arm, and transcribed the distance onto the garnish ring—after carefully noting on the ring “front” so our marks were oriented correctly.
Once all four corners were marked using an indelible marker, we drew lines from corner to corner, giving us a new line to cut the garnish ring. While a hacksaw or keyhole saw might have worked, we grabbed a Dremel rotary tool, put a cutoff disk on it, and quickly buzzed the garnish ring to the correct size. Watch out! That plastic is hot! A quick rub down with the edge of a flat file took off the little bead of plastic that the rotary tool left behind.
If you’ve got a helper, it’ll be easier to tuck the electrical wiring up between the garnish ring and the roof framing. The garnish ring mounts to the ceiling with four screws, and by now, you’ll be happy to raise the roof vent lid and power up that refreshing power vent!
So How Well Does it Work?
We’ve had powered roof vents before, but moving into the reversible direction MaxxFan was a whole new experience. At first we were in the “turn the fan on, pump the air out,” mode, but then we found that reversing the flow had its place, too. One “hot inside” day we found that the evening air up roof level was just a great deal to pull inside.
The fan also provided a thermostatic control that allowed the fan to turn on at a given set point. Too cool in the morning when you leave the rig, but expected to get warmer later? Just set the fan to automatically kick on when the desired set point is hit, and come home to moving air.
MaxxAir was kind enough to provide us with their entry-level fan unit for evaluation. That means all adjustments required standing up and physically poking the electronic “keypad” system on the fan. If you have a rig where your roof vents are in a high ceiling and out of reach, spending a few extra bucks for the remote-control version will suit you well.
How well do we like the fan? Well enough that now that we’re changing rigs, we’ll take the MaxxFan out and move it to the new trailer!
Russ and Tiña De Maris are authors of RV Boondocking Basics—A Guide to Living Without Hookups, which covers a full range of dry camping topics. Visit icanrv.com for more information.
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