Although it is possible for a gas furnace to either catch fire or explode, it's highly unlikely. If there is a danger of this happening, the furnace will usually simply shut off—as it's designed to. ... If you've got a good furnace and take care of it, you won't have to worry about explosions or fires.

What causes a furnace explosion?

A furnace explosion is usually the result of ignition and instantaneous combustion of highly flammable gas, vapor, or dust that has accumulated in a boiler. The effect of the force from the explosion is often much greater than the boiler combustion chamber can withstand.

Can a furnace catch on fire?

Yes, a furnace can catch fire.

The following are reasons your furnace can catch fire: Your furnace's air filter is blocked. Your furnace's gas pressure is too high. There is a crack in your furnace's heat exchanger.