End of the Heating Season: What to Do With Ducted Heating Before You Switch to Cooling

Melbourne is roughly two weeks out from spring, and for most households the ducted heating has done its last serious work for the year. The thermostat comes down, the system stops cycling, and it disappears from mind entirely until the first genuinely cold morning next May.

That gap is the most useful window in the year for dealing with it — and the one most consistently missed. The system has just finished its hardest continuous run, nothing in the house depends on it for the next six months, and every technician in Melbourne is available. All three of those things reverse in autumn.

Why the changeover is the moment to act, not the wrong time

A heating system that has run since May has just given you a full season of evidence. If one bedroom never got warm, if the unit was noisier than last year, if it took longer than it used to before warm air arrived, if there was a smell in the first ten minutes of each run — that information is current right now. It is reproducible, and a technician can put the system through its paces and see what you have been living with.

Try to raise the same issues next April and the situation is different. The fault is described from memory rather than demonstrated, the system has been sitting idle for six months, and you are trying to book in the busiest fortnight of the year with a cold house. Anything that turns out to need a part ordered is now a problem measured in weeks of no heating.

The end of the season inverts all of that. There is no urgency, which means there is room to do the job properly.

What a winter of running leaves behind

Ducted heating works by pulling air out of the house through the return, warming it, and pushing it back out through the ceiling or floor outlets. Everything the return draws in has to go somewhere, and what does not get caught by the filter ends up in the ductwork.

Over a Melbourne winter that is a meaningful volume of material — household dust, skin and hair, fibres off carpet and bedding, pet dander, and whatever comes in on shoes and clothing. Houses are also closed up through winter, so the same air is recirculated over and over instead of being diluted by open windows.

Ductwork sitting in a roof space adds to it. Older flexible duct develops small tears at bends and joins, and connections work loose over years of thermal expansion, so the return path can end up drawing in dust from the roof space itself along with the air it is meant to be moving. If your outlets look dusty around the edges, that is not dust settling on them from the room. That is dust arriving through them.

The end-of-season checks worth doing

Some of this is homeowner work and some of it is not, and it is worth being clear about which is which.

The filter is entirely yours and it is the single highest-value thing on the list. Find the return air grille — the large one, usually in a hallway ceiling or wall — and check the filter behind it. After a season of running it will be visibly loaded. A blocked filter makes the system work harder for less air, which costs efficiency during the season and leaves more material in the ductwork afterwards.

Grilles and outlets are also yours: a vacuum over the supply outlets and the return face removes what has accumulated on the visible surfaces. Note which rooms underperformed while you still remember, because that list is what a technician actually needs.

What is not homeowner work is anything inside the unit or up in the roof space. Gas ducted heaters have combustion components and a heat exchanger, and those are for a licensed technician — not because the work is mysterious, but because a compromised heat exchanger is a carbon monoxide risk and it cannot be assessed from the hallway. Walking on ceiling joists in a Melbourne roof space is also a good way to put a foot through a ceiling. Ducted heating cleaning and any internal inspection sit on the professional side of that line.

The return air grille is the part most people miss

Almost all attention goes to the outlets, because those are the ones you feel air coming out of. The return is the one that determines what the system is working with.

Every cubic metre of air the system delivers has to be drawn in through that grille first. If it is restricted — a loaded filter, a rug pushed against a floor return, furniture moved in front of a wall return over winter — the whole system is starved regardless of how clean the supply side is. Weak airflow at the outlets very often turns out to be a return problem rather than a fan problem.

The return is also the point where the air quality question is decided. It is the one place where all the household air converges before being redistributed, so anything getting past it goes everywhere. That is why it collects most of the visible dust, and why it is the right place to start rather than the last thing to check.

If the same ductwork also carries cooling

Plenty of Melbourne homes run add-on cooling through the heating ducts, or have a reverse-cycle system doing both jobs through one set of runs. If that is your setup, the changeover matters more, not less.

The ductwork is about to do the opposite job. Instead of carrying warm dry air through a cold roof space, it will carry cold air through a roof space that gets extremely hot. Cold surfaces in hot humid air attract condensation, and any dust already in the run now has moisture available to it. A duct system that came through winter merely dusty can develop a musty smell over its first few weeks of cooling, which is why the first hot day of the year is such a common trigger for people noticing a problem that has actually been building since winter.

Insulation on the duct is worth attention for the same reason. Duct insulation that has been crushed, torn or pulled loose over the years costs you very little during heating and a great deal during cooling, because the temperature difference between the air inside the duct and the roof space around it is far larger in summer. Damaged insulation is also where condensation forms first.

What to do before the first warm day

The order is straightforward. Deal with the filter and the grilles now while it is fresh. Write down which rooms underperformed. Book anything that needs a technician while the calendar is open rather than in the fortnight everyone else is booking.

If the same system runs cooling, run it briefly on a mild day before you actually need it — not on the first 35-degree afternoon of the year. A short test run tells you whether the changeover has gone smoothly at a point where a problem is an inconvenience rather than an emergency, and it gives you time to arrange HVAC service without competing with everyone else who waited.

FreshDuct services ducted heating, split systems and evaporative cooling across Melbourne seven days a week, with no call-out fee and before and after photos on every job.

Frequently asked questions

Why service ducted heating at the end of winter rather than before next winter?

Because the system has just told you everything it is going to tell you. Noises, weak outlets, uneven rooms and smells are all fresh and reproducible now, and a technician can see the result of a full season of running. Wait six months and the evidence is gone, the fault is not reproducible on a warm day, and you are competing with the autumn rush for a booking.

Should the heater be switched off at the wall over summer?

Isolating a gas ducted unit at the end of the season is reasonable and stops it cycling on from a stray thermostat command. The exception is a reverse-cycle system, where the same unit provides cooling — that one stays on and changes mode instead.

Does the ductwork need cleaning if the system only ran for one winter?

It depends on what the ducts are carrying rather than how long they ran. Every hour of operation pulls household dust, pet hair and fibres through the return, and in an older roof space it also pulls in whatever is sitting around the duct runs. If outlets are dusty, airflow has dropped, or anyone in the house has had a rough allergy season, it is worth having looked at.

Is it worth doing anything if the ducts also run the cooling?

Yes, and it matters more in that case. Shared ductwork goes from carrying warm dry air to carrying cold air within weeks, and cold ducts in a hot roof space attract condensation. Anything damp or dusty in the run has a much better environment to develop in over summer than it ever had over winter.