The Nomadic Cooling X2 Helix Gen II and X3 Helix rooftop air conditioners both fit the industry-standard 14 x 14 in roof opening, so the roof side of the job will feel familiar to anyone who has swapped an RV air conditioner. The new part is the DC power: heavy cable and a fuse from the battery bank. This guide walks through what comes in the box, what to check before you cut, the install order Nomadic gives, and the mistakes that cause leaks and poor cooling. It is a planning guide, not a substitute for the manual that ships with your unit; where they differ, follow Nomadic's manual.
Before you start: is DIY right for you?
Nomadic says the X2 Helix Gen II can be installed by skilled DIY customers or professional installers who are comfortable with roof openings, sealing, DC wiring, fusing, battery protection, airflow separation and rooftop component planning. If you are not comfortable cutting or preparing the roof, sizing DC wiring, protecting the circuit, lifting the unit into place or checking the finished install, Nomadic recommends a qualified installer. Nomadic also notes that improper installation, incorrect wiring, over-tightening or poor sealing can affect warranty coverage.
What comes in the box
Nomadic lists these parts with the X2 Helix Gen II, and the same set plus an air separator screw with the X3 Helix:
- The rooftop unit, black or white
- Foam gasket for the standard 14 x 14 in roof opening
- Foam-wrapped crossbars with mounting hardware
- Flush-mount powder-coated metal interior faceplate and black faceplate screws
- M8 mounting bolts, nuts, flat washers and lock washers
- Remote control
- Leveling strip and foam air separator
- Control panel and wire harness
- Full-size 1:1 cutout template for the 14 x 14 in opening
The Gen II X2 uses its revised base with directional water-management fins, so it does not include the older Gen I snorkel-style condensation parts. Power cable and a fuse are not in the box; plan those separately.
Step 0: plan the location
- Use the template first. Nomadic's 1:1 template shows the opening, gasket area, mounting path and vehicle orientation. Tape it down and look at the whole roof before you cut anything.
- Check what is under the roof. Nomadic asks you to confirm the opening does not hit structural ribs, wiring, plumbing, solar panels, vents, roof rack parts or other rooftop equipment. In a van, roof ribs often decide where the unit can go.
- Check the footprint. The X3 Helix is 31.5 by 30.9 in and stands 7.36 in above the roof, so leave room around it for solar panels and racks. The X2 is the more compact X-Series package; confirm its latest dimension sheet with Nomadic or with us before you plan a tight roof.
- Opening tolerance. Nomadic's guidance for the X2 allows about plus or minus 1/2 in on the 14 x 14 in opening.
- Plan the cable run. Measure from the battery or DC distribution point to the roof opening. On 12V, a long run means very heavy cable; see our 12V vs 48V guide.
Replacing an existing rooftop unit? If the old one used a 14 x 14 in opening, the cutout may already be right, but check the opening size, the roof around it and any ceiling ducting before you order. Our RV air conditioner replacement guide covers removing the old unit.
The install order Nomadic gives
Nomadic's X3 Helix page lists a basic install sequence that follows the familiar X-Series flow:
- Prep and dry-fit. Confirm or cut the 14 x 14 in opening and verify clearance with the 1:1 template. Dry-fit before sealing and plan the wire routing.
- Gasket and placement. Seat the gasket, set the unit in place and confirm it is level.
- Secure. Install the crossbars and hardware and tighten evenly in a criss-cross pattern. Compress the gasket evenly and do not over-torque.
- Interior assembly. Install the air separator and faceplate. Nomadic advises installing the redesigned air separator as directed for best airflow.
- Electrical. Connect the DC supply (12V or 48V to match the unit), route the harness and make sure the fuse is accessible.
- Commission. Power on, then check airflow and that the unit reaches and holds temperature.
The X2 Helix Gen II adds integrated leveling feet to its base. Nomadic is clear that they help the unit sit correctly on real roofs but do not replace proper roof prep, gasket setup or correct mounting.
Sealing the roof
The foam gasket and even crossbar pressure are what seal the unit to the opening. Follow Nomadic's manual on whether and where sealant goes at the unit itself, and do not improvise there. Nomadic's own X-Series install kit includes a polyurethane adhesive sealant and wide thermo tape, which tells you sealing matters to them as well.
Around the job, there are usually other holes to deal with: old screw holes from a previous unit, a vent you moved, or cable entry points. For those, we carry Dicor products:
- Dicor Self-Leveling Lap Sealant: Dicor's secondary seal for roof edges, air vents, vent pipes and screw heads on EPDM, TPO and PVC roofs. Dicor gives about 4 hours to waterproof and 30 days to full cure in 50–70°F weather.
- Dicor Butyl Seal Tape: the primary seal under vent, skylight and accessory flanges. Clean, dry surfaces, and do not stretch it.
See the full Dicor range for roof care.
Wiring and fusing
This is the part that differs most from a 120V unit. The X2 on 12V is rated at up to 64 A, and the X3 12V's provisional Full AC figure is about 88.6 A. Nomadic's X-Series install kit uses a 15 ft harness in 2 AWG for 12V and 24V, and 8 AWG for 48V, without a fuse; Nomadic says to install overcurrent protection per the X2 or X3 manual and your electrical system. Keep the run as short as you can, protect the cable where it passes through panels, and check your battery's BMS can supply the current. Our general wire gauge, fusing and torque guide covers the basics.
Common mistakes
- Uneven or over-tightened crossbars. The gasket needs even compression; criss-cross tightening and the right torque matter.
- Skipping or misfitting the air separator. Nomadic lists airflow separation among the install details that affect cooling and condensation; fit it as the manual directs.
- Not leveling the unit. Condensation management on the Gen II depends on leveling, gasket compression and airflow separation as well as its water-management fins.
- Undersized cable or no fuse near the battery. At 12V, voltage drop and heat build fast.
- Cutting before checking ribs and wiring. Use the template and look under the ceiling first.
Taking delivery
Rooftop units travel by LTL freight with curbside delivery. Inspect the crate and note any damage with the driver before you sign. Every Nomadic unit we sell ships from our warehouse in Upland, California, with free shipping to the lower 48 states.
Questions
Does a Nomadic rooftop unit fit my existing 14 x 14 in opening?
The X2 Helix Gen II and X3 Helix are designed for the industry-standard 14 x 14 in opening. Measure yours and check the roof around it before you order.
Do I need the Helix Pulse to install or run it?
No. Nomadic says the Helix Pulse is not required for X2 app control; it is an optional wall screen for the wider Helix system.
Which model should I install?
Compare them in Nomadic X2 vs X3 vs S1, and check the power side in how much battery you need. Shop the Nomadic Cooling range, or send us your roof layout and battery details and we will help you plan.