Shouldn't my furnace turn off after so long if it doesn't ignite?

My furnace has a bad gas valve that if like to put off until next fall/winter to take care of. It'll only be about a week before we won't need the furnace anymore. I'm pretty sure I have a bad gas valve because I can smack it a few times and then the furnace will ignite.

What I'm worried about is overnight while we're sleeping and while we're at work sometimes it does not ignite but the furnace will be on the entire time until I turn it off or smack it till it ignites.

1. Is it supposed to turn off after so long? I've had it still running when we have it set to 70 degrees but the house dipped to 65 degrees. That's 5 degrees it ran without igniting.

2. Is it harming my furnace if it's running this long with no heat?

submitted by /u/derrtybird
[link] [comments]