Thanks again for taking the time to comment.
I've been changing the filter every 3 months, but since you suggested every 1 month I'll start doing that.
If I owned this house, I would definitely be adding more attic insulation. I think that (plus the 1950's windows--no storm windows at all) are the major leak problems here.
Even if I planned on renting for the next 5 years or so, I'd go ahead and pay for the insulation myself. But as I said, I might be moving next year.
Actually, if I owned the house, I'd put in a woodstove heater. To me, that's the best heat around.
I've been able to keep my electric bill in a pretty good range. But the gas bill has been too high, so thought I'd get good advice on FR.
I really do appreciate your replies!
Glad to do it. BTW if you don't have one get a Carbon Monoxide detector. I've never had a gas furnace myself but I live in the Tennessee Valley and electricity is cheaper.