New BlDucted vs Ductless Heat Pump: Why We Often Recommend Ducted Over a Mini Split in Every Room

When a house has no ductwork, most people assume the heat pump conversation starts and ends with ductless mini splits. That is not the only option.

This post walks through the ducted versus ductless decision the way it happens at an in-home consult:

• Why a mini split head in every room usually means an oversized system

• What a ducted heat pump does instead

• The hybrid middle ground

• Where to put ducts in a house built without ductwork

Another question that comes up all the time with baseboard homes is electrical, and we touch on that too.

The homes where this question matters most are the electrically heated ones, and we have written before about replacing electric baseboard heaters with a heat pump. We worked on one Squamish house this fall, a 1970s split-level on electric baseboards, where the owners were mid-renovation with new windows in, new siding and exterior insulation on the way, and a heat pump on the list. They wanted the heat pump for air conditioning: the whole upper floor got warm in summer, and the back bedroom was the hottest room in the house. We hear this all the time from homeowners with baseboards: "We don't have any ducting, so we figure that means the mini splits option."

1. First, we scan your house

Before anyone talks about equipment, we scan the house. The scan uses lidar to build a 3D map of every room, with no photos of the interior, and from that map we run a heat loss calculation for each room so we know how much heating and cooling it needs. The whole design, and every option in the proposal, flows out of those room-by-room numbers.

The scan also lets us model the house as it will be, not just as it is. In this case the owners had the window invoice handy, so the U-value and solar heat gain numbers went straight into the model, and the three inches of exterior insulation going on with the new siding went in on top of the 1970s wall assembly. Exterior insulation is a larger improvement than it looks because it covers the thermal bridging at every stud, and in this house it took the modelled heat loss down by about twelve percent before anything mechanical had been chosen. The owner's partner summed it up on the spot: "The more you seal up, the less power you need."

That matters for the ducted versus ductless decision in two ways. A tighter house needs smaller equipment, which moves you away from the oversizing problem described next. If you go ducted, a tighter house also needs smaller ducts, because the airflow to each room is proportional to its heat loss.

2. Why a mini split in every room turns into a five-ton outdoor unit

On a ductless system, the outdoor unit has to be matched to the combined capacity of every indoor head connected to it, with a factor on top. The smallest indoor head most manufacturers make is around 7,000 BTU. A small bedroom or a home office in a well-insulated house might only need 1,000 BTU on the coldest day, so that one head adds 6,000 BTU of outdoor capacity the house will never use.

Do that for five or six rooms and the picture changes quickly. A house whose measured load fits a three-ton heat pump can end up needing a five-ton outdoor unit, not because the house got bigger, but because the heads did. The equipment costs more, it cycles more because it is too large for the job, and the owner paid for capacity they cannot use.

Each manufacturer also caps how many indoor heads one outdoor unit can run, usually three to five on a residential-size system. If you want every room served, a whole-house ductless design often runs out of connections before it runs out of rooms, which is why we end up putting a small duct somewhere anyway. There are products built to run many heads from one outdoor unit, and they are designed for commercial buildings and priced accordingly, so they are rarely the right fit for a house.

One counterweight: ductless heads have a genuine advantage, and it is room-by-room temperature control. A guest who likes to sleep cold and a child who kicks off every blanket can each have their own setting. If that is the thing you value most, ductless can still be the right answer, and the consult is where we work that out together.

3. The ducted heat pump: one system, sized once, shared by every room

A ducted system takes the opposite approach: we size one indoor unit and one outdoor unit to the house's measured load, and then we divide the air between the rooms. If the house needs three tons, we install three tons. The division happens through dampers in the ductwork, which we set so that each room's airflow matches its share of the heat loss calculation. That setting process is called air balancing, and it is part of every ducted install we do, not an extra.

In the rooms, you see a grille rather than an appliance. A wall-mounted head is a piece of equipment you look at for fifteen to twenty years. A grille stays where it is while the equipment behind it changes whenever it needs to, and most owners find it the cleaner look. The owner's partner in this Squamish house said it plainly: "I love things when they're not tucked away on the wall."

There are two more benefits. A ducted system runs the whole house's air through one thick MERV 11 filter, which keeps dust down and takes out the majority of wildfire smoke, something a wall-mounted head's small filter does not do, and fresh air can be brought into the house through the same system. Modern sound-attenuating duct also means rooms no longer echo into each other the way old ductwork did.

Ducted equipment is sized to the house rather than to the count of rooms, and that right-sizing shows up in the equipment cost, partly offset by the cost of the ducting itself. Which side of that trade-off wins depends on the house, which is why the proposal always shows both. The same design work applies across the corridor, and it is the backbone of our ducted heat pump installation in North Vancouver, where the older housing stock raises the same no-ducts question week after week.

4. The hybrid option, where the thermostat becomes the boss of the house

Between all-ductless and all-ducted sits a hybrid that works well in a lot of split-levels: one ceiling cassette or wall unit in the big open living space, and one small ducted unit tucked out of sight that picks up the bedrooms. In this Squamish house the first version of the design did exactly that, with a compact ducted unit in an attic pocket serving the three upstairs rooms and two rooms below, and a separate unit for the living room on the other side of the house.

The trade-off with two zones is the thermostat. Wherever the thermostat sits becomes the reference temperature for everything on that zone, so if the living-room zone is satisfied on a July afternoon, the bedroom zone does not get a say unless it has its own thermostat. We talked through putting the bedroom zone's thermostat upstairs so the bedrooms, which were the whole reason for the project, always get cooled first. The owner saw the other side of it immediately: "If the thermostat up there, the risk is that the basement gets too cold."

Simon's answer was that none of these permutations is a bad outcome, only better and worse versions of good, and there are plain fixes for each. A heating load and a cooling load are different sizes, so a system balanced for winter can overcool a lower floor in summer. The fix is a balancing damper you close for the season and open again in the fall, and running the fan continuously evens out the floors when one zone is satisfied before the other. You learn the system and you live with it.

5. Where ducts hide in a house built without ductwork

The question that stops most people from considering ducted is a practical one: where would the ducts possibly go? The answer in a split-level is usually the spaces nobody uses. In this house there was a dead cavity where a fireplace chimney used to run, an uninsulated attic pocket behind a bedroom closet, closets that reached the attic, and a corner on the lowest floor where a short bulkhead could carry a duct without anyone noticing it. Simon's reaction to the chimney cavity was close to delight, because a chase like that is a ready-made route.

The first design tried to reach the lower floor through the crawl space, and it meant opening the hatch wider to get equipment in and sorting out the crawl space's ground vapour barrier at the same time. Four days later Simon called the owners because the route had been there all along: go from above. The main trunk crosses the attic, drops down inside the wall, and picks up the lower rooms through wall grilles beside where the chimney used to be. Here was the result: the crawl space was out of the project entirely, and the encapsulation became a separate job the owners could do whenever they liked.

The attic pocket became a small mechanical room, insulated and vapour-sealed, with the ducted unit inside it. Making that pocket part of the conditioned house also trimmed the heat load, because fewer surfaces now face outdoor air. The ducts that cross unconditioned attic space get insulated and sealed so they never sweat, and the trunk and branches are sized to keep the air moving slowly enough that you do not hear it arrive. You see a lot of 1970s split-levels like this one across Garibaldi Highlands, Valleycliffe, and Brackendale, and most of them have a chase or an attic pocket that can do the same job.

What we will not do is run refrigerant line up the outside of the siding to save a drywall cut. It is a quick way to install a wall unit and it does not look good in the end. If there is a route up an internal chase, even one that means some careful cutting and patching, we take it. When we do open drywall, the cuts are square, the dust is vacuumed at the blade, and the pieces go back where they came from.

6. Your electrical panel is probably fine, thanks to the baseboards

Almost every baseboard conversation includes a worry about the electrical panel, so here is the answer up front: replacing electric baseboards with a heat pump usually leaves you with capacity to spare. Heating with a heat pump draws roughly a third of the electricity that heating with baseboards does, so once the baseboards come off the panel, the heat pump generally fits on the existing service. Code requires us to allow for the rated power and the motor's start-up draw, and even with that allowance it works out.

Where a panel upgrade does come into the picture, it is usually driven by the other things on the list, like a vehicle charger or a hot tub, rather than by the heat pump. If an upgrade is planned for later, the prep is one wire run to the old panel location ahead of time, so the heat pump moves over to the new panel without opening walls twice. In this house the heat pump was designed to go onto the existing panel the day the baseboards were disconnected, with the service upgrade able to happen on its own schedule.

7. Tell us about the renovation you keep talking about at dinner

Every consult includes a question about what else is planned for the house, inside and out, and it is not small talk. This owner mentioned a possible roofline change ten or more years out that would turn the attic pocket into a bigger primary bedroom and bathroom. With a ducted system, more square footage is a distribution question rather than a capacity question: if the insulation is good, a well-sized system can take on an extra room with a new duct run and a rebalance, provided a chase for a supply and return duct is planned into the new space. The indoor unit itself can be moved down a level if the roofline changes.

A ductless system handles a future addition differently, because the new rooms need their own heads and the outdoor unit may already be at its head limit. Knowing the plan now, even a vague one, lets the design leave room for it. That is also why we would rather hear every idea, including the ones you have shelved, than find out about them after the equipment is in. If you are weighing HVAC in Squamish for a house with a renovation in its future, bring the sketches.

8. The option Simon would pick for his own house

Asked what he would do if it were his own house, Simon said the full ducted system. With everything on one zone the thermostat question disappears: it goes somewhere central, out of the sun, on the middle floor, and the air balance keeps the bedrooms and the lower floor in line with it. The owners' own summary of the project was the shortest one we heard in two visits: "No AC to AC is a huge jump."

The ductless proposal was on the table beside it the whole time, and the owners asked plenty of questions of both. That is how it should go. Our job at the consult is to measure the house, lay out the options with their trade-offs, say which one we would pick and why, and leave the decision where it belongs.

Ducted vs ductless: the questions we get asked most

Can you put a ducted heat pump in a house with no ducts? Often, yes. Split-levels and older homes usually have an attic, a closet that reaches the attic, a chase where a chimney used to be, or a corner where a short bulkhead can run. A compact ducted unit in an attic pocket or a closet can serve several rooms through those routes without touching the crawl space or the outside of the house.

Is a mini split in every room cheaper than a ducted heat pump? Not necessarily. Each head adds to the outdoor unit's required capacity, and the smallest heads are larger than small rooms need, so a whole-house ductless design often ends up with more equipment than the house's measured load calls for. Ducted equipment is sized to the house, with the ducting as the added cost. Which comes out ahead depends on the house, and a proposal that shows both is the way to find out.

Do I lose room-by-room temperature control with a ducted heat pump? Each room does not get its own setting the way it would with a ductless head. What you get instead is one balanced temperature set from a central thermostat, with dampers that let you close off a room or a floor for a season. Room-by-room control is the strongest case for ductless, and for some households it decides the question.

Will a ducted system cool the upstairs bedrooms? Yes, when the system is balanced for the bedrooms. The airflow to each room is set from that room's share of the heat loss calculation, and a summer setting can push more of the cooling upstairs where the sun hits. With a single zone, the thermostat goes somewhere central so no floor gets forgotten.

Do I need a panel upgrade to replace electric baseboards with a heat pump? Usually not for the heat pump itself. Removing the baseboards frees more capacity than the heat pump needs, because it heats on roughly a third of the electricity. Upgrades are typically driven by vehicle chargers and hot tubs. We check the panel at every consult rather than assume.

How long does a ducted heat pump last? The average is around fifteen years, and a well-maintained system can run twenty. A grille in the room outlasts any of it, and the equipment behind it can be replaced without redoing the ductwork.

Finding out what your house needs

If your home is on baseboards and the heat pump conversation has stalled at "we have no ducts," the first step is the measurement, not the equipment. At an in-home consult we scan the house, run the heat loss room by room, walk the closets and attic with you looking for routes, and lay out the ducted, ductless, and hybrid options with their trade-offs attached. You can book an in-home consult five days a week, and nothing gets decided on the spot unless you want it to.

If you would like the full picture before anyone comes out, our guide Thinking About a Heat Pump? Read This First covers what to know about the process from the first conversation to the first cold snap.

We are Porcupine Mechanical, a Squamish-based mechanical contractor working from the North Shore up through the Sea-to-Sky, from North Vancouver to Squamish to Whistler, on residential heating, cooling, and ventilation. Our whole thing is doing it efficiently and doing it right the first time.