Confused about the source of the water the furnace produces. If they don’t destroy water vapor and outside air is dry, where is all the water coming from? Referring to modern 95+% efficiency furnaces used in northern climates. These have two side wall tubes — one input, one output, plus require a floor drain or reservoir with pump to remove the water. Always amazed by the amount of water I see coming out of the drain tube from the furnace. My current system has no duct humidifier or water line leading to the furnace.

HRV recover heat only. ERVs, the membrane type recover upwards of 82% of the moisture and heat both summer and winter. The right ERV is used in the bath to bring in outside air and exhaust the humidity. Depending on the particular situation, use of an HRV may be better. The best ERVs do not allow odors to pass across the membrane thus providing fresh air to the space and removing odors. This is also a very efficient way to manage CO2. Super tight structures with occupants will soon have an abundance of indoor CO2. You will probably notice this before you notice the moisture. Outside air has a CO2 concentration just above 400 ppm, Exhaled air is at about 40,000 ppm. Demand Control Ventilation DCV has three parts to manage with one system. CO2, Relative Humidity and tVOC or for most of the world that means odors but it can be lots of things.
It has been my experience that most doors and windows themselves are better than the installation issues. Check the gap around them and most have enough unoccupied space to allow massive extraction of air from the space with no appreciable drop in pressure. A foam sealant for doors and windows can greatly reduce the air leakage enabling much better humidity management without compromising buildings or occupants.

10% is not a bad variation for humidity percentage for residential level sensors. Commercial level equipment is somewhat better, but much more expensive and requires yearly recalibration.

I had a similar issue with temperature readings on these and the thermostat. Eventually, I took an guesstimated average to determine the appropriate offset for the thermostat. Now they are all four in the ballpark as far as temperature readings.

I had gas for years and loved it but my new (lifetime) favorite appliance is my Dacor induction cooktop. Super fast and responsive and so easy to clean. Gas wasn’t an option at our newly built house and I have no regrets.

Fred, I was just reading your comment about the minerals we breathe from humidifiers showing up in the products of combustion from your gas cooktop. Wondering which is worse the minerals or the products of combustion?

Yes but RO water is just not good enough. It is 15-30 ppm and puts a bunch of minerals into your air and lungs. It was enough in my house that it showed up as yellow gas burners on the stove. I take RO water and put it thru one of these zero filters. RO water extends the filter life and I end up with 0 ppm and proof for me was that the gas burners went back to bright blue. Less dust too and more healthy for the home occupants as well.