Wall heater blowing cold air
Same symptom, different unit. Read this if you've got a wall furnace.
Help guide · Ducted systems
Ducted heating on but blowing cold air? We'll find why.
Fan kicks in, you hear airflow at the vents, but the air's barely warmer than the room. Frustrating — especially on the cold mornings Adelaide actually has. The fan and the burner are two separate systems on a ducted unit, and when one runs without the other you've got a fault that's almost always fixable in a single visit.
All major brands
Same-day metro
Common parts in van
Upfront quote
60–120 min on site
Full diagnostic
Compliance cert
What's happening
Fan running, burner not firing
A ducted gas system has two main pieces working together: the burner makes heat, the fan moves air across the heat exchanger and pushes it through your ducts to the rooms. When everything's healthy, the controller calls for heat, the burner fires up first, and the fan kicks in 30–60 seconds later once the heat exchanger is warm.
If the fan is running but the air is cold, one of two things is happening. Either the burner never fired in the first place — and the fan is just blowing room-temperature air — or the burner fired briefly and then cut out on a safety lockout, leaving the fan running its post-purge cycle.
Both situations are common and most of them are fixable on the first visit. The trick is methodically working through the system: thermostat, controller, gas supply, ignition, flame sensor, gas valve. We carry a manometer, a multimeter, and the common spares for Braemar, Brivis, Bonaire, Vulcan, Rinnai and Pyrox in every van.
Safety check
Is this dangerous?
Mostly no. A ducted system that won't heat is annoying, but the safety systems are doing their job — the burner isn't running, so there's no combustion to go wrong. CO risk is essentially zero in this fault state.
The exception: if the heater is firing intermittently and you can smell anything unusual at the vents (gas, soot, "burning electrical"), turn the system off at the controller and the unit's isolator switch and ring us. If you can smell raw gas anywhere in the house, ring 1800 427 532 first.
Right now
What to do in the next 5 minutes
1
Check the controller
Set point above current room temp. Mode is HEAT, not FAN. Check for any error codes on the display.
2
Check the filter
Pull the return-air filter out and check it isn't choked with dust. Blocked filters trigger overheat lockouts.
3
Reset the unit
Switch the isolator at the unit OFF for 30 seconds, then back ON. One reset attempt — no more.
Diagnosis
What's likely causing it
- Blocked return-air filter. Common and easily missed. Dust starves the fan, the heat exchanger overheats, the safety switch locks the burner out. Fan keeps running to cool things down. Replace the filter and you may be back in business.
- Thermostat or controller fault. Old wall thermostats develop intermittent contacts. New touchscreen controllers can lose calibration or get stuck in fan-only mode. We test with a known-good thermostat and replace if needed — $180–$320.
- Ignition system failure. The control board calls for heat, the gas valve opens, but the spark or pilot can't light the gas. After 3 attempts the unit locks out and runs the fan to cool. $110–$180 igniter or $45–$140 flame sensor clean usually fixes it.
- Gas valve stuck or coil failed. Less common but does happen on units 10+ years old. The control board sends the signal but the valve doesn't open. $400–$650 fitted.
- Zone damper stuck. If only some rooms get heat and others don't, you've got a zone damper jammed. We can usually free or replace the actuator the same visit.
- Control board fault. Last thing we check because it's the most expensive. $480–$950 fitted. We always rule out the cheaper causes first.
DIY?
Can I fix it myself?
You can do three safe things before calling us:
- Replace or clean the return-air filter (fixes about 15% of "no heat" calls on its own).
- Check the thermostat batteries if it's battery-powered.
- Cycle the unit's isolator switch off for 30 seconds, then back on.
That's the safe DIY list. Anything past that — opening the unit, touching the gas valve, replacing parts — has to be a licensed gas fitter under SA's Plumbing, Gas and Electrical Services Act 1995. Even electrical work inside the unit is restricted.
When to call
Call us today if
- Filter, thermostat batteries and reset didn't fix it
- You can see an error code on the controller (have it ready when you ring)
- The fan runs but the unit never seems to fire
- Heat works in some rooms but not others (zone damper)
- The system hasn't been serviced in 2+ years
Honest pricing
How much will the repair cost?
2026 Adelaide pricing, GST included, no call-out fee. Diagnostic is included in the repair price — you only pay extra if we end up doing a full service alongside it.
- Filter replacement only: $80 (or free with a service)
- Diagnostic + flame sensor clean: $260
- Thermostat replacement: $260–$420
- Igniter or pilot rebuild: $260–$330
- Gas valve replacement: $400–$650
- Fan motor: $420–$780
- Control board: $480–$950
If the unit is over 12 years old and needs $1,500+ in repairs, we'll honestly tell you whether replacement makes more sense. No upselling — just an honest call.
Response time
How quickly can you come out?
Same day across Adelaide metro if you ring before 10am. Ducted heating diagnostics take 60–120 minutes on site depending on what we find. Most common-cause repairs are done in the same visit. Parts that aren't on the van (specific control boards, brand-specific valves) can usually be sourced and fitted within 24 hours.
FAQ
Ducted gas heating not heating — common questions
If the fan runs but no heat, the burner isn't firing. Common causes: stuck gas valve, thermostat fault, ignition failure, blocked filter triggering overheat lockout, or controller error.
Check the controller has power, thermostat is set above room temp, and the gas isolation valve at the unit is open. If those check out, likely a controller, fan motor, or ignition fault.
Diagnostic plus minor repair starts around $260. Igniter $110–$180, flame sensor clean $45–$140, thermostat $180–$320, fan motor $420–$780, control board $480–$950, gas valve $400–$650.
You can change the filter, check thermostat batteries, and reset the isolator. Anything else on a ducted gas system requires a licensed gas fitter under SA gas regulations.
Same-day across Adelaide metro if you ring before 10am. Most ducted diagnostic and repair jobs are 60–120 minutes on site.
Related help
Other gas heater problems we help with
Error code on the controller
Got a number or letter showing? Decode it here.
Ducted gas heating service
Annual service from $199 — keeps these faults from happening in the first place.
Ducted heating not heating? Let's get the warmth back today.
Same-day Adelaide metro. Common parts in the van. Upfront quote before any work starts.