Top 6 Reasons Why Your Furnace Isn’t Blowing Hot Air

September 16, 2016

You rely on your HVAC to keep the house comfortable, but what if your furnace isn’t doing its job? A malfunctioning furnace may not be on your list of priorities right now, but you don’t want to be stuck without heat on a chilly evening!

Here are 6 common reasons for a furnace blowing cold air, and what you should do about it:

1. It’s Just Been Switched On – Any furnace will blow cold air when it starts up, since it takes time for hot air to travel through the system and into your home. Cold air trapped inside will need to be expelled before the hot air can take its place!

2. Thermostat is Set Too Low – Make sure the thermostat is set to a higher temperature than your home, and running on “heat” mode. If you’ve just changed the settings, wait for it to reset.

If the furnace is still blowing cold air, check the thermostat batteries. Even almost-empty batteries can cause trouble by interfering with temperature inputs. If replacing the batteries doesn’t work, get the thermostat recalibrated, or replace it with a new one.

3. Damaged or Dirty Ducting – Inspect the duct system for leaks, tears, holes and loose joints that allow heated air to escape into the basement or attic. Cold air from these spaces can also get into the ventilation if ducts are damaged.

Accumulated dirt or debris can block airflow and slow down the movement of hot air through the ducts. Most of the time, this isn’t serious enough to affect the heater, but if the airflow is completely blocked, the furnace can overheat and kick off.

4. Poor Insulation – Check the insulation in your home, especially in areas where ducts are placed. Consider adding more insulation if it’s torn, damaged or too thin, or if ducting is laid outside of it.

Poor insulation allows heat to escape your home, and ducts passing through rooms without insulation will also lose heat. As a result, the heater has to work harder.

5. Issues with the Furnace/Heater – Sometimes, the problem may be the heating system itself

Gas Furnace – See if the gas supply line valve is open (it may have been closed during the summer). For older models, check whether the pilot light is lit, and if the electronic starter is receiving power in newer models.

Electric Heater – Inspect the electrical panel for tripped circuit breakers and reset them. If the breaker that controls the unit keeps tripping, there may be a short circuit in the system. Call an HVAC professional to check it.

Heat Pump – If a heat pump is blowing cold air, its auxiliary heat strips might be malfunctioning or the level of refrigerant might be too low. Call a professional for inspection and repairs.

6. The Heater is Too Big/Small – The heater’s size makes a difference to how well it works. If the heating system is too small, it won’t warm your house efficiently. If it’s too large, it will heat up your house too fast and then keep kicking on all day.

Whether you’re using an oil or gas furnace, electric heater, or heat pump, schedule a maintenance service for it before the days get cooler. Proper heater maintenance and furnace maintenance can go a long way toward preventing problems, so call Service Champions for an appointment today!

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