I couldn't find an online manual for the GUK125D20, but I suspect the "125" is the input BTU (125,000 BTU/hr), which means it's likely to have at least 100,000 BTU/hr of output.
For reasonably tight 2x6 /R19 type construction with clear glass (not low-E) double panes that would be right sized for a ~4500-5000' house at +5F (Akron's
99% outside design temp), enough oversize capacity to cover even Polar Vortex disturbance event cold snaps. Is that your house? 100,000 BTU/hr is enough furnace output to heat my 2x4 framed sub-code 2400' house + 1600' of insulated basement with clear glass storms over the 1923 vintage wood sashed single panes down to about -100F outside, a temperature not seen in my neighborhood (or Akron's) since before the last Ice Age.
For a typical 2000-3000' new-ish house in Akron it's likely to be on the order of 3-4x oversized. (Remember, ASHRAE draws the line at 1.4x oversizing for best comfort & efficinecy in residential heating.) If it's married to a central air conditioner using the same air handler the AC is probably similarly oversized. A pretty-good 30-40,000 BTU/hr condensing 2-stage can be had for under $1500, and installation isn't rocket science- often DIY-able, but it will be more complicated and expensive if the AC has to be replaced too. If that's the case it's a good idea to get a handle on both loads. Sometimes/often the best solution is a modulating heat pump to handle both heating & cooling, even if gas is currently somewhat cheaper from an operating cost point of view. If gas is a LOT cheaper a right-sized hydro-air solution with a cooling coil and hydronic heating coil in the air handler operating off a condensing water heater can work out well.
The AC oversizing factor can be inferred by
measuring it's duty cycle on afternoons when the temperatures are near the
1% outside design temp, which in Akron is 85F. As with heating systems, oversizing the AC by more than ~1.5x is going to reduce rather than enhance comfort. To the untrained it might seem like it's "struggling to keep up" with very long on-cycles, but that will do a lot more for reducing the humidity than a 3x oversized AC in
So, go ahead and patch the furnace up- control components are relatively cheap, but start measuring your loads, think about what makes sense for a replacement.