Is your furnace causing you concern but you’re not sure on the seriousness of the problem? Sometimes a furnace seems to work as normal but makes strange and worrying noises, othertimes a furnace may switch off suddenly but be caused by a dirty filter – which you can easily replace yourself.
Knowing the difference between a regular furnace repair and an emergency furnace repair can help you to make the decision between calling a professional now, or later, and having the worry and hassle that goes with an emergency callout.
Furnace is Making Strange or Loud Noises
Noises relating to your furnace can range from innocent pops and pings to more concerning grinding, rattling and squealing. These noises can mean a whole host of things; your furnace may even be working fine with no clues as to what the cause is.
When is a furnace sound cause for an emergency call out?
- Popping / pinging noises – This can appear to come from the ductwork, in this case the cause can be thermal expansion – where the ductwork expands and contracts as the temperature goes up and down – often in cold weather.
- Bombs, bangs & thuds – Usually this means that the burner is struggling to reach the correct temperature. When this happens unburnt fuel can build up inside the furnace and when the temperature does rise enough the combusting of all this excess fuel can cause those loud noises. The causes of this can be a dirty burner or pilot light, misaligned burner or gas supply pressure problems. Bangs coming a few feet away from the furnace can originate in the ductwork and be caused by a dirty fair filter or ductwork, closed air vents/dampers and undersized ductwork.
- Screeching or Squealing sounds – A common noise with furnaces, this can indicate a slipped or worn belt, faulty/damaged fan motor or loose/unlubricated bearings. These are not the most dangerous of noises but you should schedule a repair as soon as possible to prevent undue damage.
- Whistling noise – A whistling sound is most likely caused by a dirty and clogged air filter which is restricting airflow.
- Clicking sounds – It’s normal for a furnace to click when it starts up, this is the sound of the ignition. If the sound continues once the furnace has got going then it could be caused by bearings or the inducer fan in an oil furnace. A clicking sound where the furnace doesn’t turn on can be caused by a faulty flame sensor, pilot light or damaged/clogged ignitor. It can also be a sign of a clogged gas valve or dangerous gas leak and should not be ignored.
- Rattling sounds – Could also be a sign of a broken fan blade, loose material or panels within the furnace – and sometimes the ductwork. Sometimes tightening a panel is all that’s needed. This is not an immediate cause for concern.
- Rumbling noises – This can be caused by a build-up of sediment on the heating element, or a leak coming from the heat exchanger. This is not something that should be ignored and you should call an emergency pro to help diagnose the issue.
- Grinding noises – This usually suggests that the motor in the air handler is under strain and that the bearings are causing friction – needing a replacement. You should schedule a repair as soon as convenient to prevent damage, though this may not be an immediate emergency.
When to call a professional?
If you are concerned then speak to a professional, they may be able to help guide you over the phone based upon your descriptions. In many cases furnace noises – though scary are not cause for immediate concern. Don’t ignore rumbling and clicking sounds (where the furnace doesn’t start) as these can be indicative of leaks so it’s best to get them checked out. In any case it’s not good to delay diagnosis and/or repair as damage to your furnace can occur over time.
The Pilot Light Isn’t Blue
A problem with older furnaces that have pilot lights. A healthy flame will always be blue in color. A flame more yellow in color can mean insufficient oxygen and the presence of carbon monoxide – known as the silent killer. Carbon Monoxide has no smell, taste or color.
When to call a professional?
If the flame on the pilot light remains yellow call a professional.
The Heat Suddenly Disappears
This can be caused by a tripped circuit breaker, thermostat whose batteries have died or a clogged air filter. As concerning as this can be this is not always an immediate emergency.
When to call a professional:
If you’ve checked your circuit breaker, air filter and thermostat then call a professional.
The Furnace Rapidly Switches On and Off
Also known as short cycling, the first place to check is a dirty or worn air filter. You can try a new filter to see if this solves the problem.
When to call a professional?
If you’ve already tried a new filter and the furnace is still short cycling then there may be a problem with the belts or blower motor which should be diagnosed by a professional.
Unpleasant smell (rotten eggs / sulphur)
A smell of gas is quite distinct and should not be ignored. Natural gas does not have a smell so instead mercaptan is added which is reminiscent to rotten eggs and quite noticeable.
If you can smell gas get out of the home immediately especially if you hear a hissing sound.
Don’t turn on or off any lights, or the stove. Do not use the phone in your house, call an emergency professional from outside.
Turn the gas off only if you can safely do so. Here’s a guide from PGE.
Any Other Furnace Problem
For any other furnace problems you experience a reputable emergency professional should be able to help assess the severity of most issues over the telephone. In many cases they can put your mind at rest as to whether a repair is needed urgently, in the near future or not at all.