1. Do this ^^^^^^. GFCI breaker or receptacles are required in damp locations. I would take it out and put in a normal duplex receptacle. Moisture in a basement or crawl space, even in the damp air will activate the GFCI. If you don’t stand in water when you plug it in you will be ok and so will everything else. If only one Romex cable runs into the junction box then it’s not feeding other receptacles (which is ok).
2. And yes a gas furnace must have a drain line.
3. I’ll split the $250.00 service call with
@jjwestbrook. PayPal friends please.
Note: I have spent the whole day helping one of our members on GFCI circuits because some inspection company has insisted for refinancing a complex, GCFIs are necessary. Problem is nothing has been wired correct and the ground faults are not working on half of them after installation due to issues on the load side of the ground fault receptacle.
I have 10 more circuits tomorrow to find the lead breaker and why the GFCIs will not reset. Lots of receptacles in multiple living areas and lights on the kitchen counter receptacles. It’s a long process.