Dometic EnviroComfort Dual Duct Kit for 6K BTU EDC Retrofit

The Dometic EnviroComfort Dual Duct Kit (MPN 9108750550) lets you split the airflow from a single 6,000 BTU EDC retrofit AC unit between two cabin outlets. Instead of cooling one cabin only, you can route conditioned air to two separate cabin spaces using the included Y-duct splitter, supplementary ducting, and adjustable airflow dampers.

Why this matters for small cruising boats. Boats in the 22 to 30 foot range typically have a v-berth at the bow, a small head, and a main saloon area. A single small AC unit is sized for that whole interior heat load, but routing all the cooling to one outlet leaves the other spaces warm. The dual duct kit splits airflow so cooling reaches both major cabin spaces. The dampers let you bias airflow toward the space that needs more cooling at any given time (v-berth at night for sleeping, main saloon during the day for relaxing).

Compatibility. The dual duct kit is sized for the EDC 6,000 BTU retrofit family. Larger AC units (10K, 16K BTU) have their own dual-duct kits with appropriately larger duct sizing. Match the duct kit to your AC unit's BTU rating. Using a 6K duct kit on a larger AC unit restricts airflow and can damage the AC over time from elevated condenser temperatures.

What's in the kit. The Y-duct splitter that attaches to the AC unit's output, two adjustable airflow dampers (one for each branch), supplementary insulated ducting, and the hardware needed for typical install configurations. You may need additional duct length or fittings depending on your specific cabin layout, especially if the second cabin outlet is far from the AC unit's mounting position.

Install. The install adds maybe 30 to 60 minutes to a standard AC install. You attach the Y-splitter to the AC unit's output instead of a single duct, route ducting to each of the two cabin outlets, and install the included dampers in-line on each branch. The dampers let you adjust airflow distribution after install based on how the boat actually performs.

Why not just run two smaller AC units instead. Two reasons. First, two units take up more compartment space and need separate power circuits, separate seawater plumbing, and separate drain routing. The single-unit-plus-dual-duct approach is more efficient in installed-space and complexity. Second, two units are more expensive and more failure points. The single-unit approach with dual ducting is the standard small-boat installation method for two-cabin cooling.

One consideration on cooling effectiveness. Splitting airflow between two cabins necessarily reduces the cooling capacity per cabin compared to a single-cabin install. For boats where one cabin needs to be substantially cooler than the other (overnight sleeping cabin vs. day cabin), the dampers let you bias the airflow accordingly. If both cabins need full cooling simultaneously and the 6K BTU isn't enough capacity, that's a sign you need a higher-BTU AC unit rather than just a duct splitter.

A practical note on damper positioning. Place each damper in-line on its respective branch of the duct, several feet downstream from the Y-splitter and several feet upstream from the cabin outlet. That positioning lets the airflow stabilize before metering and lets the airflow re-energize after metering before delivery to the cabin. Placing dampers immediately at the Y-splitter or immediately at the cabin outlet creates turbulence patterns that reduce overall cooling effectiveness.

Insulation maintenance over time. The insulated ducting in the kit is sized for typical run lengths but eventually the insulation can compress at zip-tie points or absorb moisture over many years of marine service. If you notice cooling effectiveness declining without a corresponding decline in the AC unit itself, inspect the duct runs for insulation degradation. Replacement insulated duct is available as a separate accessory if you need to upgrade or replace sections.