Demystifying Gas Furnace Repairs

When it comes to gas furnace repair there are normally very few problems, and those that may occur are pretty standard. Usually it has something to do with the pilot light, the thermocouple or one of the electrical components.

There are a few things that you can safely check yourself before calling a repairman, but remember the number one rule is safety first.

Before attempting any gas furnace repair check if you can smell gas. If there is a smell of gas:

  1. DO NOT switch any lights or plugs on or off – the electrical spark could cause an explosion.
  2. DO NOT try to shut off the gas yourself.
  3. DO get everyone out of the house immediately, leaving doors open.
  4. DO call the gas company and the fire department and report the leak.
  5. DO NOT go back inside until the problem is resolved.

General Gas furnace Run-Through

It is important that you have some general knowledge about how your furnace works before attempting any gas furnace repair, so here is a very quick run-through. A gas furnace usually looks somewhat like a box, and its main functions are:

  • Cold air is sucked into the unit.
  • The air is then cleaned via an air filter.
  • A gas burner then heats up the air via a stainless steel heat exchanger.
  • Clean warm air is distributed throughout the building via ductwork by a blower motor.
  • Once the air in the rooms cools down it is re-introduced to the furnace through ductwork and air grills and the cycle begins again.

Gas Furnace Repair Checks

If you are having problems with your furnace and there is no smell of gas, then there are certain steps you can take to check what the problem is before calling someone to do the gas furnace repair, so that you can tell them what the possible problem is:

  1. Make sure that the furnace is switched on.
  2. Check the filter to see if it is possibly dirty.
  3. Check the door cover to see if it is closed properly.
  4. Make sure that there are not too many registers that are closed.
  5. Check to see whether there are no blown fuses or tripped circuit-breakers.
  6. Ensure that the gas is on and the pilot light is lit.
  7. Check that the outside gas furnace vents are not blocked.
  8. Check that the batteries for the programmable thermostat are not stale.
  9. Ensure that the blower fan is switched on.

Once you have checked all of those details, you can call the gas company and inform them of what the problem is so that they know what is expected of them when they come to do the gas furnace repair and can ensure that they bring the right equipment and replacement parts with them. This will save you time on repairs, as the technician will not have to go back to the factory and come back to effect the repairs at a later stage. Trust me, if it is in the middle of winter you will want your heat back on as soon as possible.

DIY Gas Furnace Repair

If you are a handy type of person and like to do things yourself, you can solve many of the smaller problems by finding out what the problem is. Refer to the following troubleshooting guide for assistance in doing the gas furnace repair yourself:

PROBLEM – The Furnace is very noisy when operating.

Possible Cause:

  • If the furnace is making a high-pitched sound like a pig squealing, it could because of a belt that is slipping or shaft or motor bearings that need to be oiled.
  • If the noise is a lower rumbling sound like thunder, it could be due to the pilot light not being set correctly if it happens when the gas furnace burners are off.
  • If the lower rumble occurs when the burners are on, it could be due to dirty burners.

Possible gas furnace repair:

  • Oil the blower motor lubrication ports.
  • Check that the tension of the blower belt is correct – you should be able to depress it about 1″ at the centre. If too loose tighten it and if frayed replace it.
  • Adjust the pilot light.
  • DO NOT attempt to clean burners yourself – call the technician.

PROBLEM – The furnace is producing no heat at all.

Gas Furnace RepairPossible Cause:

  • The thermostat is either set too low or broken.
  • There is a broken fuse or tripped circuit-breaker.
  • The batteries on the digital component are flat.
  • There are loose wires or a bad connection.
  • Pilot light is out.
  • Gas in not turned on.

Possible gas furnace repair:

  • Check that the thermostat is at the correct setting in heat mode.
  • Replace fuse or reset circuit-breaker.
  • Replace batteries for digital component.
  • Repair wiring.
  • Relight the pilot light.
  • Switch gas on.

PROBLEM – The furnace is producing insufficient heat.

Possible Cause:

  • The furnace air filter is dirty.
  • Gas burners are dirty or need to be adjusted.

Possible gas furnace repair:

  • Clean or replace the air filter.
  • DO NOT adjust your burners yourself – call your service technician to do so.

PROBLEM – The Blower never switches off.

Possible Cause:

  • The thermostat is set to the “fan continuous” mode.
  • There is a problem with the fan limit control switch.

Possible gas furnace repair:

  • Change the setting on the thermostat fan. Check that the running time is not too short or too long.
  • Replace or reset the fan limit control switch.

PROBLEM – The furnace switches on and off too frequently.

Possible Cause:

  • The air filter is dirty.
  • There is a problem with the blower motor.
  • There is a problem with the thermostat (heat anticipator).

Possible gas furnace repair:

  • Replace the air filter.
  • Oil the lubrication ports of the blower motor with light-weight oil; they can usually be found at the end of the shaft.
  • Adjust the thermostat heat anticipator.
  • Check that the tension of the best is right; if not, tighten or replace the belt.
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