The Different Types of Mini Split Air Handlers: An In-Depth Guide

Mini split (ductless) heat pump systems give you a choice of four main indoor unit (air handler) styles: wall-mounted, floor-mounted, ceiling cassette, and concealed ducted. Each shape solves a different room layout problem. For southern New Hampshire homes, knowing which style fits which room is often the difference between a satisfying install and one the homeowner second-guesses every time they walk past.

At A.J. LeBlanc Heating, we install all four styles across NH. Here is an honest comparison of where each one wins and where each one struggles.

1. Wall-mounted air handlers

The most common style by a wide margin. A streamlined indoor unit roughly the size of a wall-mounted soundbar, installed high on an interior or exterior wall.

Pros:

• Easiest and least expensive to install
• Wide range of capacities to fit any room size
• Good for retrofit additions to existing rooms (a single line set penetrating an exterior wall serves the unit)
• Available in basic white, premium black, and other finishes from some manufacturers
• Highest-efficiency models in the lineup

Cons:

• Wall presence is noticeable; some homeowners object to the appearance
• Requires wall space free of artwork, shelves, or furniture below
• Air discharges in one direction, which can produce uneven temperatures in long rooms

Best fit:

Bedrooms, living rooms, finished basements, three-season porches, additions. Most common choice for NH retrofit installations.

2. Floor-mounted air handlers

Resemble a low-profile radiator, mounted at the base of a wall. Some models can be recessed into the wall for a more integrated appearance.

Pros:

• Ideal for rooms with limited wall space above (large windows, vaulted ceilings, sloped ceilings)
• Lower profile than wall units; less visually dominant in some installations
• Air discharges from low in the room, which works well for heating-dominant applications
• Some models can be partially recessed into the wall

Cons:

• Consumes floor space
• Lower capacity options than wall-mounted units
• Less common, so fewer model and capacity choices

Best fit:

Sunrooms with floor-to-ceiling windows, three-season rooms, finished basements where wall space is at a premium, rooms with vaulted or sloped ceilings.

3. Ceiling cassette air handlers

Installed flush with the ceiling, with only the discharge grille visible. Air discharges in four directions across the ceiling, providing more uniform distribution than a wall unit.

Pros:

• Almost invisible from the room (only the discharge grille shows)
• 4-way air distribution provides even temperatures across large or open spaces
• Ideal for finished basements with low ceilings (some slim-profile models fit in 9 inches of clearance)
• Suitable for open floor plans where a wall unit would only serve part of the space

Cons:

• Installation is more involved (requires ceiling cavity space and access)
• Not all NH homes have adequate ceiling space (joist spacing, plenum height)
• Maintenance access is overhead and slightly more difficult
• Higher install cost than wall-mounted

Best fit:

Open-concept living areas, large finished basements, commercial-style spaces, homes where the wall-mounted unit's appearance is a deal-breaker.

4. Concealed (ducted) air handlers

Fully hidden in a ceiling cavity or above a soffit. Connected to short duct runs that deliver air through ceiling or wall registers. The most invisible option.

Pros:

• Completely hidden, no indoor unit visible
• Can serve multiple rooms from a single concealed unit through short duct runs
• Looks and behaves like a traditional ducted system
• Ideal for new construction or major renovations where ceiling access is already planned

Cons:

• Most invasive to install (requires access to ceiling cavity, duct routing)
• Highest install cost
• Maintenance access is the most difficult
• Short ducts mean static pressure tolerance is limited; long duct runs can compromise performance

Best fit:

New construction, gut renovations, homes where indoor unit visibility is unacceptable, rooms where a short duct run can serve multiple smaller spaces.

Mixing styles on a single system

One of the genuine advantages of mini split systems is that you can mix and match indoor unit styles on a single outdoor compressor (a multi-zone configuration). Common combinations:

• Wall unit in the master bedroom + ceiling cassette in the open living/kitchen area + floor unit in the sunroom
• Concealed ducted unit serving multiple small rooms + wall unit in a large great room
• Wall units in bedrooms + floor unit in a finished basement

Each indoor unit operates as its own zone with its own thermostat or remote, while sharing the single outdoor unit. This is often more efficient and more comfortable than trying to serve diverse spaces with a single forced-air system.

Brands we install

A.J. LeBlanc Heating installs mini split equipment from the major residential brands we carry for NH installations: Mitsubishi (we are a Mitsubishi Diamond Dealer), Daikin, Fujitsu, LG, and Bosch. All five offer the full range of indoor unit styles. The right brand depends on the application, the available rebates, and the cold-climate performance you need.

Schedule a mini split consultation

If you are considering a mini split system for your New Hampshire home, contact A.J. LeBlanc Heating for a no-pressure consultation. We will walk through which indoor unit styles fit each room and design a system that actually works for your home. Serving New Hampshire families since 1928.

Frequently Asked Questions

Which mini split indoor unit style is most efficient?

Wall-mounted units generally have the highest published efficiency ratings, partly because they require no ductwork. Ceiling cassettes and floor units are close behind. Concealed ducted units lose a small amount to duct friction but are still highly efficient.

Can I mix different indoor unit styles in one home?

Yes. A multi-zone outdoor unit can support multiple indoor units of different styles, each in its own zone with its own thermostat. This is one of the genuine advantages of mini split systems for NH homes with varied room layouts.

How many indoor units can one outdoor unit support?

Most multi-zone outdoor units support 2 to 8 indoor units. Total capacity needs to be balanced; you cannot oversize the indoor units relative to the outdoor unit's capacity.

Are ceiling cassettes good for low ceilings?

The slim-profile cassette models from Mitsubishi, Daikin, and LG can fit in as little as 9 inches of ceiling clearance. Standard cassettes need more like 12 to 14 inches. A licensed installer measures available cavity space before specifying.

Do concealed ducted mini splits work like a central system?

Yes, with limitations. The unit is sized for relatively short duct runs and modest static pressure. They work very well for serving 2 to 4 rooms from a single concealed unit; they are not designed to replace a full whole-house central system.