I have a new 80% efficiency Gas forced air furnace w/ variable speed motor. I've been getting cycles that are around 11 or 12 minutes long from the beginning of the current cycle to the beginning of the next cycle, with the temp in the upper 30s in Northern NJ. Is it worth changing the "System Type" from 6 to 3 (assuming it won't allow 5 or 4) so as to reduce the number of cycles per hour? (although I realize this may make the temp fluctuate more)
Since the system has an inducer motor and ignitors, etc. I'm wondering if reducing the cycles per hour would cause less wear and tear on the inducer motor and ignotors, etc.?
I'm also curious if reducing the cycles per hour would cause MORE wear and tear on the burners and heat exchanger, since the burners would be running longer (if the thermostat intentionally waited until 20 minutes have elapsed since the start of the previous cycle to begin the next cycle)?
FWIW, My new Carrier is a 2-stage, and I do NOT have a 2-stage stat (and have no plans on getting one). My understanding is that the furnace won't switch into the 2nd stage unless it has been running on stage 1 for 15 minutes.
One reason (other than reducing wear and tear on the ignitors and inducer motor) that I'm tempted to reduce the cycles setting from 6 to 3 is because I can hear a low pitched hum for around 35 seconds during the ignition phase and I'm told this is the inducer motor. I don't really like hearing the sound, since it is something I never heard before with my older pilot-based furnace. Even though the furnace doesn't seem that loud during the ignition phase in the basement where it is located, I can hear that low pitched hum all the way upstairs in certain rooms. By limiting the cycles to 3 per hour, I would only have to hear that hum 3 times per hour instead of 6 (athough I suppose I will eventually get used to the hum and not notice it)
By the way, the inducer fan blade wheel is a circular piece of plastic that appears to be imperfect (not perfectly symetrical). I asked the installer if the blade wheel were perfectly symetrical would the hum be reduced and he said 'no' because there is a lot of play how the motor is mounted/housed. There is something about how the motor is mounted that allows for movement (I guess kind of like how cars have shock absorbers). Am I being told a lie about how it's okay that the plastic fan blade wheel isn't perfectly symetrical?