Having never owned a home before, and certainly never having had to service a furnace before, what signs should I look for that my furnace is past the point of serviceability and simply needs replacement? That giant cloud of gas that forms in the basement shortly before detonation is an obvious one - what others?
Some facts about my situation, but I guess I'm more interested about the general case.
My particular gas furnace is approx 25 years old. It seems to heat just fine, however its startup behavior seems weird to me.
basically, tick, tick, tick, tick, .......(about 10 seconds later) then ignition, burners doing their stuff for about 10 seconds, blower comes on and air starts moving. Burners shut down blower shuts down 10 to 15 seconds later.
All of this seems normal, but I'm wondering why it takes so long for the gas to ignite (I assume the tick, tick, tick is the sound of the igniter sparking) and whether or not this is one of those things where you just close you eyes and walk away.
I keep my filters clean and change it regularly.
At what point would I KNOW that this furnace is DOA and shouldn't be repaired? At what point should I just call in the HVAC dude and have him/her/it repair it?