A ductless mini split is a heat pump split into two pieces: a compact outdoor unit and one or more indoor heads, connected by a refrigerant line set that needs roughly a three-inch penetration through the wall. It heats and cools, it runs on a zone-by-zone basis, and it solves the single most expensive problem in an old house — the fact that there is nowhere to put ducts.
Which homes actually need ductless?
- Houses that never had ductwork. Homes heated historically by gravity furnaces, radiators or space heating often have no return path and no chases.
- Additions and conversions. Sunrooms, enclosed porches, bonus rooms over the garage, finished attics and basements the original system was never sized to reach.
- Detached garages and shops where extending the house system is impractical.
- One room that is always wrong. The west-facing bedroom that bakes, the office over an unconditioned space.
- Homes where duct replacement is not worth it. If the existing duct system is undersized, buried in plaster or largely outside the envelope, ductless can beat rebuilding it.
- Anyone who wants real zoning — separate setpoints per room, without a damper system.
Why is ductless such a fit for Boone County?
Because the housing stock outside Columbia's newer subdivisions is genuinely old, and the numbers are not close:
| Community | Median year built | Age of stock |
|---|---|---|
| Rocheport | 1938 | 58.0% built before 1940; 63.9% before 1950 |
| Hartsburg | 1938 | 52.7% built before 1940 |
| Sturgeon | 1958 | 53.6% before 1960; 74.7% before 1980 |
| Centralia | 1971 | 62.2% before 1980; 530 units predate 1940 |
| Columbia | 1993 | 17,817 units (31.8%) built before 1980 |
A house built in 1938 was framed without any expectation of forced air. Retrofitting real ductwork into it means furring out walls, giving up closet space or dropping ceilings. Ductless sidesteps all of that — which is why our guide to mini splits in old homes is one of the pieces Sturgeon and Rocheport homeowners read most.
What's included in a ductless installation?
- A room-by-room load calculation — zone sizing is where ductless jobs succeed or fail
- Head placement planned for throw, sightlines and condensate drainage
- Core drilling and a sealed, sleeved wall penetration
- Line set, control wiring and condensate routed together, in a line-hide cover where it is visible
- Outdoor unit on a pad or wall bracket, raised for winter defrost runoff
- Dedicated electrical circuit and disconnect
- Deep-vacuum evacuation, nitrogen pressure test and a verified charge
- Remote and controls configured, heating and cooling modes both tested
- Permit filed where the work requires one
What does the process look like?
- Walk the space. We look at each room you want conditioned, the exterior wall options and where the outdoor unit can live.
- Zone plan. Single-zone or multi-zone, how many heads, and which style fits each room.
- Proposal with the equipment tier and any rebate we expect to apply.
- Installation — most single-zone systems go in within a day; multi-zone takes longer.
- Commissioning and walkthrough — filters, modes and controls explained before we leave.
What indoor unit styles are there?
| Style | Where it works |
|---|---|
| High wall head | The default — bedrooms, living rooms, offices; highest efficiency per dollar |
| Floor console | Rooms with knee walls, dormers or low ceilings; sits where a radiator used to |
| Ceiling cassette | Open areas with attic space above; four-way discharge from a flush grille |
| Short-duct air handler | Feeds two or three small rooms from a closet or soffit — useful in historic homes where visible heads are unwelcome |
| Multi-zone outdoor unit | One condenser serving several heads on independent setpoints |
Does a mini split qualify for a Columbia rebate?
It can, because a ductless system is a heat pump. The Columbia Water & Light efficiency tiers — $800 at SEER2 15.2–18.1 and $1,200 at SEER2 18.2 or higher — are the starting point, and the $1,200 Efficient Electrification rebate applies when an existing home leaves gas or propane, subject to minimums of 1.5 tons and 15.2 SEER2 and the rule that no rebate is available if the system being replaced already contained a heat pump or electric furnace. Ratings come from the AHRI Directory, the program is replacement-only, and you must be a City of Columbia Utilities electric customer. Outside the city — including all of Rocheport — Boone Electric runs its own programs. We confirm the exact configuration against the rules before you buy; see the full Columbia rebate guide for every line item.
What affects the cost of a ductless system?
- Number of zones — each indoor head adds equipment and labor
- Head style — wall units cost less installed than cassettes or short-duct handlers
- Line set length and routing — especially through finished or masonry walls
- Electrical — whether a new circuit and disconnect are needed
- Efficiency tier — and whether it clears the rebate threshold
- Outdoor unit placement — ground pad, wall bracket or roof-adjacent mounting
- Cold-climate capability — equipment rated to hold output at low outdoor temperatures
Where we install ductless systems
We install ductless across Columbia and Boone County. In Sturgeon, where more than half the housing predates 1960, ductless is often the difference between a comfortable house and a space heater in every room. In Rocheport, with a median build year of 1938 and buildings dating to the 1830s, the question is usually how to condition a house without tearing into it. In Columbia, Historic Old Southwest and East Campus have the same pre-war construction — and a lot of attic and porch conversions. Related services: heat pump installation, A/C installation, duct cleaning for homes that do have ducts, and maintenance plans that cover ductless equipment.
Ductless Mini Split FAQs
Do ductless mini splits heat as well as cool?
Yes. A mini split is a heat pump, so the same equipment cools in July and heats in January by running the refrigerant cycle in reverse. In a Columbia winter, with a normal January low near 21 degrees, we either specify a cold-climate model or plan a backup heat source for the coldest stretches, the same way we would for any air-source heat pump.
How many indoor units does a house need?
It depends on the floor plan, not the square footage alone. One outdoor unit can serve a single indoor head or several, and each head conditions the space it can see. Open-plan main floors often take one larger head, while a house chopped into small rooms needs more zones or a short-duct air handler feeding two or three rooms from a hidden location.
Will a mini split work in a house built in the 1930s?
That is exactly the case ductless was invented for. Balloon-framed houses from the 1930s rarely have chases wide enough for real ductwork, and cutting them in means losing closet space and ceiling height. A mini split needs only a three-inch penetration per indoor unit for the refrigerant line, condensate and control wiring.
Are ductless systems noisy?
The indoor head is quiet because the compressor is outside, and inverter-driven systems spend most of their time running at low speed rather than cycling on and off at full blast. The outdoor unit is comparable to a conventional condenser and can usually be placed away from bedroom windows.
Does a ductless system qualify for the Columbia rebate?
A ductless system is a heat pump, so the Columbia Water and Light efficiency tiers of $800 at SEER2 15.2 to 18.1 and $1,200 at SEER2 18.2 or higher are the right place to start, and the Efficient Electrification rebate of $1,200 carries minimums of 1.5 tons and 15.2 SEER2 when a home is leaving gas or propane. The program determines ratings from the AHRI Directory and applies to replacements for City of Columbia Utilities electric customers, so we confirm the exact configuration against the program before you commit.
Can I add a mini split to just one room?
Yes, and it is one of the most common jobs we do. A sunroom, a bonus room over the garage, a finished attic, a converted porch or a home office that the central system was never sized to reach can each get a single-zone system without touching the rest of the house.
Do mini splits need maintenance?
Yes. The washable filters in each head need regular cleaning, and the blower wheel and coil need periodic professional attention because there is no duct system or central filter cabinet in front of them. Ductless equipment is covered by our annual service agreements.