It's 30 years old and when I came home I smelled something gassy. We had to get out of the house.
Sounds like they found a crack in your heat exchanger. The heat exchanger transfers heat from the combustion area to the air circulating in your home. The reason for the smell is the crack is allowing combustion gas ( carbon monoxide) into the circulating air. You only have two options, replace the heat exchanger or replace the entire furnace. If the furnace is 30 years old I would replace it with a higher efficiency unit.
cracked exchanger is a very good reason to get a new furnace. air is actually sucked in on a cracked exchanger making the flame very erratic and will roll out your flame causing your most danger. chances are you have several cracks unseen you ve had for yrs but they re getting more numerous or big enough to be changing your flame. do it soon
If you know there is a crack there is no need for further investigation, replace it. Call at least 3 diff. HVAC Co. get bids from them. Depending where you are it will cost $2500.00 up depending on what you buy. In Calif. if a crack is found in the unit, state law requires the unit to be red taged and disconected from the gas untill fixed. good luck.
USA Frozen and Francis are correct. You can replace the heat exchanger. However, an old furnace is not nearly as efficient as today's are. You can get a furnace that is 92% efficient - that means 92% of the energy put into the furnace as fuel is converted to heat. Old ones are 70 to 80% at best. A high-efficiency furnace properly installed will save money on your fuel bill. But, before going through all that, have a licensed HVAC technician go over your system and find out exactly what happened.
If there's a crack in the firechamber, it could kill you, literally. You've heard of Carbon Monoxide I assume, that's what will be escaping from the crack in the firepot into your home. You won't smell it, you just won't wake up.
