Adding a Second Marine Air Conditioning Zone
The short answer
Usually a second self-contained unit sharing the existing seawater loop, which is far cheaper than the first because the through-hull, pump and electrical work already exist. Extending ducting from the original unit is the tempting alternative and it is usually how one cabin ends up short.
Adding a Second Boat AC Zone — Requirements and Limitations
Check the existing pump first. Two units on one pump is normal, but the pump has to be sized for both, and an original pump chosen for a single unit may not have the capacity. The same goes for the electrical circuit.
If ducting extension is genuinely the right call — a short, straight run to a nearby space — insist on balancing dampers. Without them the new grille simply steals air from the old one.
Related Sizing, Installation and Service Guides
Each of these answers a different part of the same problem.
- what two zones needscapacity and architecture together
- ducting that worksif you extend rather than add a unit
- the two-unit bandwhat the second one actually costs
- the fault this createswhen the new zone starves the old one