Is Ducted Heating Right for Your Otago or Southland Home?

In a lot of southern homes, winter settles into a familiar pattern: one room is warm and the rest aren't. You've got the lounge heat pump going, the family's all crowded into one space, and the moment you walk down the hallway to bed it's like stepping outside. Plenty of Otago and Southland homes live like this for half the year, and most people just accept it as normal.

Ducted heating is the answer to that problem. Instead of heating one room well and the others not at all, it warms the whole house evenly — quietly, and out of sight. If you've started looking into it, you've probably already got a sense that it's a bigger commitment than bolting another heat pump on the wall. So the real question isn't usually what does it cost — it's is this the right system for my home, and how do I know it'll actually keep up when it matters?

That's what this article is about.

The short version: Ducted heating warms your whole home evenly and out of sight — the comfort you don't see, but feel every winter morning.

At a glance:

• One hidden unit feeding every room — even warmth, with no wall boxes to look at
• Goes in the ceiling, or under the floor on homes up on piles
• Sizing it for a genuinely cold southern morning matters more than anything else
• Zoning means you heat only the rooms you're actually using
• It heats and cools, and runs far cheaper than plug-in heaters
• We design it to your home and give one fixed quote — no price list, because no two homes are alike

What a ducted system actually is

The idea is simple once you've seen one. A single indoor unit sits hidden away — most often in the ceiling cavity — and from there a network of insulated ducts carries warmed (or cooled) air to discreet grilles in each room. Outside, there's one outdoor unit, much like a normal heat pump. No wall units in the lounge, no boxes in the bedrooms — just even, gentle air and a controller on the wall.

The ceiling isn't the only place it can go. On homes built up on piles with enough room underneath, the unit and ducting can be installed in the subfloor instead, delivering air up through floor registers and grilles rather than down from the ceiling. The principle is identical — the equipment just lives below the floor instead of above it — which makes ducted a real option for plenty of older homes that don't have a usable roof space.

In the older housing stock we work in all the time — the villas of North East Valley, the bungalows around Mosgiel and St Clair, those solid 1970s brick homes you find right across Dunedin, Invercargill and Oamaru — ducted heating is often the most practical way to get true whole-home comfort without cluttering every room with equipment.

The question that really matters: will it keep up?

This is where a southern install is different from one in a milder part of the country, and it's the thing we'd encourage you to focus on above all else.

A ducted system has to be sized to your home — matched to how much heat your house loses on a properly cold morning. Get that calculation right and the system holds the whole house at temperature without breaking a sweat. Get it wrong, and you've got a system that looks fine on paper but can't quite get there on the coldest mornings of the year — which, of course, are exactly the mornings you bought it for.

The temptation, always, is to fit something slightly smaller because it looks tidier on a quote. We'd steer you away from that every time. In our climate an undersized system is the single most common regret we're called in to fix. We do a proper heat-loss calculation for your specific house rather than sizing by rule of thumb, because the cost of getting it wrong isn't measured in dollars — it's measured in cold July mornings for the next fifteen years.

What shapes the system your home needs

A few things about your house determine what we'd specify, and they're worth understanding so the conversation makes sense when we visit.

The size and layout is the obvious one — a bigger home needs more capacity and more ductwork, and the number of rooms drives how many grilles run back to the central unit. A compact two-bedroom flat is a very different job from a sprawling four-bedroom family home.

Ceiling or subfloor access matters more than people expect. A villa with a generous roof void is a joy to work in; a flat-ceilinged 1970s house where every metre of duct has to be threaded through tight spaces takes more time and care. Where there's no usable roof space but the home sits on piles, a subfloor install can be the answer instead. Either way, access shapes the design.

Insulation is your system's quiet partner. A well-insulated ceiling means the system works gently and efficiently. Minimal insulation — common in pre-1980 homes here — means it has to work harder, and you'll feel that on your power bill. We always ask about insulation at the site visit, because it affects both the sizing and your realistic running-cost expectations.

And then there's zoning, which is worth a paragraph of its own.

Heating rooms you're actually using

Zone control lets you heat or cool different parts of the house independently — bedrooms cool through the day, living areas warm in the evening, the guest room shut off entirely until someone visits. It's one of the smartest things you can build into a ducted system, because you stop paying to warm rooms nobody's in.

Mitsubishi Electric's ZoneIQ system integrates directly with their ducted units and lets you manage all of this from your phone. It adds a little upfront, but for most family homes it pays its way back in comfort and reduced running over the years. (If you want the full picture, see Zone control for ducted heat pumps).

Duct design: how the air gets in, and how it gets back

Here's a part of ducted design that rarely comes up in a sales conversation but makes an enormous difference to how well the system actually performs: it's not just about getting warm air into a room, it's about giving that air a way back out to the return.

There are two main approaches. The first puts a supply grille in every room and brings the air back through one large central return grille — sometimes two, say one in the living area and one in a hallway. The second puts both a supply grille and a (smaller) return grille in each room.

The central-return approach is cheaper and perfectly fine — as long as internal doors stay open. The trouble starts when they're closed. With the return sitting out in the hallway, air pumped into a closed bedroom has no easy path back to it; the room pressurises, airflow falls away, and that room stops performing. The usual fix is to undercut the doors to let air flow underneath — but the research is clear that a normal door gap often can't pass nearly enough air, and you'd need a surprisingly large undercut to balance a room properly. Fine if the doors are always open; a real problem if they're routinely shut — think kids' or teenagers' bedrooms.

What we usually do to sidestep the whole issue is fit a supply and a small return grille in each space. That keeps the pressure balanced and the system working perfectly whether the doors are open or closed — no undercut doors, no door grilles needed. It's a bit more ductwork and a few more grilles, so there's some extra cost, but in a home where bedroom doors spend a lot of their life shut, it's well worth it.

Run it with ventilation: ducted plus Lossnay

A ducted heat pump can also be paired and integrated with a Mitsubishi Electric Lossnay heat-recovery ventilation system. This is one of the more elegant setups we install. The two systems talk to each other, so even when the ducted unit isn't actively heating or cooling, the Lossnay can instruct it to tick over at a low fan speed — quietly circulating fresh, filtered air through the whole house around the clock.

The result is a healthier, drier, more efficient home from a single integrated heating, cooling and ventilation system, all manageable over Wi-Fi. And it's not only for new builds — you can retrofit ventilation to an existing home too (see Can I install heat recovery ventilation in an existing home?).

How efficient is a ducted heat pump?

Heat pumps are an efficient way to heat, and that's the whole appeal. In our winter conditions a well-sized ducted heat pump will typically return somewhere around two and a half to four units of heat for every unit of electricity it draws — the exact figure shifts with how cold it is outside — where a plug-in resistive heater gives you just one.

We're deliberately careful, though, about putting a dollar figure on running costs. It's tempting to quote a tidy annual number, but the reality is that what a system costs to run depends enormously on how warm you keep the house and how well it's insulated, and those vary so much from home to home that any figure we gave you would be more likely to mislead than help. What we can point you to is hard data: the input power every unit draws is published for each model on the Mitsubishi Electric New Zealand website and in the data sheets, so you can see exactly what a given system will pull.

Ducted or multi-head — which is the honest answer for you?

It really does depend, and we won't pretend otherwise. Multi-head systems — one outdoor unit feeding several wall units — are often the better, more sensible choice in smaller homes, or where you only really need heat in a few specific rooms. Ducted comes into its own when you want consistent warmth right through the house, when you'd rather not look at a wall unit in every room, when you're building new and can plan the duct runs into the design, or when you want proper centralised zone control.

Sometimes, after we've walked through a home, the better recommendation is multi-head — and we'll tell you that even though ducted is the bigger job. We'd rather you ended up with the system that suits how you actually live.

What does ducted heating cost in Otago and Southland?

It's the first thing everyone wants to know, and the answer is simply that there's no single figure — because no two homes lose heat the same way. The size and layout of the house, how many rooms you're warming, how easy the ceiling or subfloor is to work in, your insulation, the duct design, and whether you add zoning all move the number. That's exactly why we don't publish a price list: a number plucked from a webpage is far more likely to mislead you than help you.

What we do instead is come and look at your home, design the right system for it, and give you a single fixed quote with no surprises. If you'd like a real number for your house, the fastest way to get one is to book a free site visit.

How we'd approach it

When we quote a ducted system we include the design and load calculation, the Mitsubishi Electric indoor and outdoor units, all the ductwork, grilles and fittings, the electrical connection, commissioning, and warranty registration. One thing we won't compromise on is duct insulation — all our supply ducts are insulated properly, because in a cold climate that's the difference between an efficient system and one that sweats and wastes heat in your roof space.

You won't see a ducted system in the architectural photos — it lives in the ceiling — but you'll feel it every winter morning. It's one of those quiet things that turns a well-built house into a home you actually want to be in. The only way to spec it right is to see your place in person, so there's no obligation and no hard sell — just an honest plan that fits.

Thinking about whole-home heating? Get in touch and we'll arrange a time to come and have a look.

Frequently asked questions

How much does ducted heating cost in Dunedin?
There's no fixed price — cost depends on your home's size, layout, ceiling or subfloor access, insulation, duct design and whether you add zone control. Rather than quote a misleading figure, we design the right system for your home after a free site visit and give you one fixed price.

Is ducted heating or a multi-head heat pump better for my home?
It depends on the house. Multi-head systems often suit smaller homes or where you only need heat in a few rooms. Ducted comes into its own when you want even warmth through the whole house with no wall units on show. We'll give you an honest recommendation either way.

Can a ducted heat pump cool as well as heat?
Yes. A ducted heat pump both heats and cools, so the same system keeps you warm through an Otago winter and cool through a hot Central Otago summer.

Can ducted heating be installed in a home with no roof space?
Often, yes. If your home is up on piles with enough room underneath, the system can be installed in the subfloor and deliver air up through floor registers and grilles instead of ceiling diffusers. Where there's no workable roof space or subfloor, we'll tell you straight and look at the alternatives with you — usually a multi-head system. It's one of the first things we check on a site visit.

Warm and Cool are HVAC specialists based in Dunedin, serving Otago and Southland. We design, supply, and install heating, cooling, and ventilation systems for homes and commercial buildings throughout the lower South Island.