The ducted gas heater has finally gone
A ducted gas heater usually dies in the first cold week of the year, which is the worst possible time to think clearly about it. This is the short version of what your choices are, and which one is worth waiting a few days for.
The short answer
If the heat exchanger has cracked, the unit is finished and no one will repair it. If it is a fan, a board or an igniter and the unit is under about twelve years old, a repair is usually fine. Beyond that you are choosing between another gas unit and a ducted reverse cycle system. Reverse cycle costs more up front and gives you cooling as well. In Victoria it has the largest single rebate in the country behind it. It can usually reuse your existing ducts. Get your ceiling insulation looked at before anybody sizes it.
First question
Ask the technician whether the heat exchanger is cracked. If it is, stop. That unit is not coming back and it should not be run.
Before sizing
Say what insulation and sealing work you have done or plan to do. It changes the unit size, and a smaller unit is cheaper twice.
About the ducts
In most homes the existing ducts can be reused for reverse cycle. Ask, because a quote that assumes all new ductwork is a very different price.
Is it actually dead?
One fault ends the conversation. The rest are repairs.
A ducted gas heater burns gas in a sealed metal box called a heat exchanger, and blows house air over the outside of it. The two air streams never meet. When that box cracks, they can, and that is the fault that ends the unit’s life. No technician will repair it and no honest one will let you keep running it.
Almost everything else is a repair. Fans, control boards, igniters, gas valves and thermostats are all parts, and on a unit under about twelve years old a repair usually makes sense. Past fifteen, you are spending money on something that is going to ask again next winter.
So the first thing to ask, before any price is mentioned, is which of those two you have. If nobody has said the words heat exchanger, ask directly. It is the difference between a few hundred dollars and a few thousand.
Safety, briefly
Has your carbon monoxide alarm gone off? Has anybody in the house had headaches or nausea that got better when they left? Turn the heater off at the gas and get it tested before anything else. This is the one part of the decision that is not about money.
The three options
What each one costs you, now and later.
Repair it
Right answer for a younger unit with a fixable part. Ask for the part price and the labour separately, and ask what else on the unit is close to going. A technician who has the cover off can usually tell you.
Why it comes here
Cheapest today, and buys you a season or two to plan properly.
Who does it
A gas fitter or ducted heating technician.
Another ducted gas unit
Fastest and often cheapest on the day. Your ducts stay, the controller stays, the job is done in a morning. It also fixes your running cost in place for the next fifteen years and gives you nothing in summer.
Why it comes here
Quick and familiar. No rebate on a gas for gas swap, and gas prices are not going backwards.
Who does it
A ducted heating installer with a gas licence.
Ducted reverse cycle
The same ducts and vents, a different box. It heats and it cools, it runs on electricity, and if you add solar later it runs partly on your own. It costs more to install and it is the option with real money behind it, at least in Victoria.
Why it comes here
Heating and cooling in one. Largest verified single job incentive in the country. Needs an electrician and sometimes a switchboard.
Who does it
A ducted reverse cycle installer, working with an electrician.
$5,530
VictoriaThe Victorian discount for replacing a ducted gas heater with a 22.4 kW reverse cycle system. Your installer claims it and takes it off the price. Other states run smaller schemes or none.
Why sizing comes last
A heater is sized to a house that might be about to change.
The size of a heating system is set by how fast your house loses heat. Add ceiling insulation and seal the draughts and it loses heat more slowly, which means a smaller unit does the same job. A smaller unit costs less to buy and less to run, every winter, for as long as it lasts.
So if insulation or sealing is anywhere on your list, do it first or at least tell the installer it is coming. A good one will size for the house you are about to have. A quote written for the house you have today can be several kilowatts too big. You pay for those kilowatts twice.
Ask how the size was worked out. The answer you want mentions rooms, windows, ceiling height and insulation. The answer you do not want is floor area multiplied by a rule of thumb.
What happens to your ducts
Usually they stay. Sometimes they should not.
Most ducted gas systems can hand their ducts straight over to a reverse cycle unit. That is a big part of why the swap is easier than people expect. The vents stay where they are and the ceiling does not get opened up.
There are two reasons an installer might want to change them. Old ducting in a hot roof leaks, so heat is lost on the way to the room. Reverse cycle also moves more air than gas does. Small ducts can whistle, or fail to reach the far end of the house.
Both are fair. What is not fair is a quote that replaces all the ductwork without saying why. Ask which of those two reasons applies, and ask whether the existing ducts could be tested or partly reused. It is often thousands of dollars of difference.
What we couldn’t confirm
The claims we could not put a source behind.
Heating quotes carry a lot of confident arithmetic. Here is what we went looking for and could not verify from a government page.
A national rebate for gas to electric heating
There is no federal scheme for heating. The large figures you may have seen are state programs, and Victoria’s is the biggest we have verified.
“Reverse cycle costs a third of gas to run”
It depends on your gas rate, your electricity rate, your climate and whether you have solar. Reverse cycle is usually cheaper to run. We will not print a single ratio that pretends to cover every home.
Fixed prices for ducted reverse cycle
The spread on this job is genuinely enormous, because house size, duct condition and switchboard work all move it. Get three quotes rather than trusting any published range, including ours.
Quick answers
The questions people ask next.
Can I heat the house while I decide?
Portable electric heaters in the rooms you actually use will get you through a week. They are expensive to run, so use them for a week, not a season.
Is reverse cycle warm enough in a cold winter?
Yes, and the number to ask for is its output at your coldest design temperature, not the headline capacity. Units are rated at a mild temperature by default and they all put out less when it is near freezing.
Do I have to disconnect the gas?
Not because of this job. If the heater was your last gas appliance, disconnecting the meter stops the daily supply charge, which is worth real money over a year. If you still cook with gas, that is a separate decision.
Will the same controller work?
Usually no. A reverse cycle unit comes with its own controller, and it is often a better one. Ask whether zoning carries over, because that is the part people miss.
What about a few split systems instead?
Perfectly reasonable, and often cheaper, especially if you only really heat two or three rooms. The trade off is a box on the wall in each of those rooms and no single thermostat for the house.
Should I wait until summer to do this?
If you can, yes. Installers are less busy, you get more quotes and better prices, and nobody is deciding while cold. If you cannot, ask for the heat exchanger answer first so at least the decision is the right shape.
What to do this week
Three things before you sign anything.
Today
Ask the technician one question in writing: is the heat exchanger cracked? Everything else follows from that answer.
This week
Get somebody to photograph your ceiling insulation. If it is thin or missing, say so on every quote you ask for.
On every quote
Ask how the size was calculated, and whether the existing ducts are being reused. Those two answers explain most of the difference between quotes.
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