Your furnace is getting old, the upstairs cooks every August, and two people have given you two different answers: a heat pump on the ducts, or heads on the walls. At Firlands Portland Mini Splits we install mini splits, not central systems, so here’s an honest comparison, including when the other answer is better.
The short version: look at your ducts
Ducts decide most of this. Sound ducts to every room favor a central heat pump; missing, partial or undersized ducts favor a mini split.
| Your house | Usually the better fit |
|---|---|
| Ducts reach every room, sized and sealed well, furnace due for replacement | Central heat pump on the existing ducts |
| Ducts serve the main floor only; upstairs or attic rooms get nothing | Mini split heads upstairs, ducted system below |
| No ducts: baseboards, wall heaters, radiators or an oil boiler | Mini split, whole house or room by room |
| Ducts exist but are small, leaky or in a crawlspace that floods | Mini split, or duct repair before a central system |
| One addition, ADU or converted garage | Mini split; extending ducts rarely pays |
Close to half of Portland homes heat with gas, and most of those have a furnace and some ducts. The question is whether those ducts can carry a heat pump’s air.
What “split system” means for both
Both are split systems: a compressor outside, a coil and fan inside, and refrigerant lines between them. The difference is how the air gets to your rooms.
A central heat pump
One large indoor air handler, usually where the furnace was, pushes air through the house’s supply and return ducts. One thermostat runs the house. In many installs the old gas furnace stays as backup heat on the coldest nights, which the trade calls a dual-fuel setup.
A mini split
Each room, or each open area, gets its own indoor unit, usually a wall head. A refrigerant line set runs from the outdoor unit to each head, so there’s no duct loss and each room has its own setting. A multi-zone outdoor unit can feed several heads.
When a central heat pump is the better choice
We’d point you to a central heat pump when your ducts are in good shape and reach the rooms that need it. Here’s why it wins there:
- It reuses what you have. Good ducts are already paid for. Putting a head in every bedroom of a house that has supply registers in every bedroom often costs more.
- One system, out of sight. No wall units, one outdoor unit, one filter to change.
- Whole-house air. Ducted systems can carry a high-grade filter and fresh-air ventilation through every room at once.
- Even temperatures. A well-designed duct system spreads air evenly, while a single head in an open room can leave far corners less comfortable.
That’s a different job from ours. A heat pump and furnace contractor tests the ducts and quotes it, and Energy Trust of Oregon runs separate incentives for ducted heat pumps that replace an electric furnace.
When a mini split is the better choice
A mini split wins when ducts are missing, partial or poor, which describes many older Portland houses. Here’s why:
- The hot rooms have no ducts. Many bungalows and foursquares heat the main floor through floor registers, and the finished attic gets nothing. A central heat pump can’t cool a room its ducts don’t reach.
- The ducts are too small. Ducts built for a furnace’s hot air often can’t move the larger airflow cooling needs, especially to a second floor.
- There are no ducts at all. Baseboards, wall heaters, radiators and oil boilers leave nothing to connect to. Building new ducts in a finished old house means opening walls and ceilings.
- You want rooms to differ. A cool bedroom at night and an office warm all day are easy with heads and hard with one thermostat.
A quarter of Portland’s homes were built before 1940, and in Northeast and Southeast Portland the share is close to two in five. Those are the houses where ductless most often wins; adding air conditioning to an old Portland house goes deeper.
The middle option: a ducted mini split
A ducted mini split hides a small air handler in an attic, knee wall or soffit, and feeds two or three nearby rooms through short new ducts.
It’s still a mini split: one outdoor unit and a line set. It suits a pair of attic bedrooms with a crawl space above, where you don’t want anything on the walls. Firlands’ typical range for a ducted mini split is $8,500 to $16,000 and up, depending on the attic access and how many rooms it serves.
Heating in a Portland winter
Both systems heat with the same physics, and both lose some output as the outdoor temperature falls toward Portland’s 24°F design low.
Backup heat
A central heat pump often keeps the gas furnace or an electric strip heater as backup. A mini split house usually keeps the old furnace, baseboards or a wall heater in place for the few hard nights. Either way, we plan the backup before we size anything (mini split sizing).
Equipment choice
For heads that heat, we choose cold-climate models that keep most of their output near 24°F. Do mini splits work in cold weather? covers ice storms and the east wind.
What it costs, side by side
We can give you our numbers for the mini split side; ask a ducted contractor for the central side and compare them line by line.
| Mini split job | Firlands’ typical range |
|---|---|
| Three or four heads upstairs | $9,000 to $18,000+ |
| Whole house, five heads or more | $15,000 to $30,000+ |
| Ducted mini split for two or three rooms | $8,500 to $16,000+ |
When you compare, line up what each quote includes: duct repair or sealing, a new circuit, removing the old furnace, permits and the outdoor unit’s spot. Mini split installation cost in Portland breaks down our side.
How we’d decide on your house
On the visit we look at the ducts before the equipment, and we tell you if they make a central system the better answer.
- We check which rooms the ducts reach, and whether the upstairs registers blow anything.
- We look at the furnace’s age and where the air handler would go.
- We work out each room’s load, then count heads (how many do I need?).
- If ductless fits, you get a written estimate. If it doesn’t, we say so and why.
Call us with your furnace’s age and which rooms are hard to keep comfortable, and we’ll tell you which way your house leans.