Bought the house in 1987. Older furnace then, but it's been running fine every year. Don't want to jinx myself, but besides inefficency, should we be doing something to it? Our house is dry in winter.

It needs cleaned periodically, combustion byproducts (dust and dirt) do build up. Burners need to be checked to correct color before you wake up dead of carbon monoxide poisoning.

They are not maintenance free. And they should be checked and cleaned at least every year or two.

Ut-oh... I guess we better get cleaning after 23 years! Thank you.

I'd recommend getting a pro to do it. He knows what to look for. You should be able to have it done for between $75 and $150. And he will be very thorough.