High Efficiency Furnace
High Efficiency Furnace with variable capacity has from begining high price. All furnace with a modulation system will have an impact later in warranty period or after. Your comfort at begining will be great and also your savings will be considerable than an 80% efficiency furnace. Between 90% and 98% we can talk about savings and more about comfort. Keep in mind a blower motor life is around 15 years. With some ECM motors I saw the electronic module issue after 8 years. The cost of those ECM motors varie between $800 to %1500
Draft motor ( Inducer)
Another issue with a high efficiency furnace is the draft motor. The average life for this motor is 10 years . For motor with variable speed the cost will double . Price varie between $400 and $1000.
Another expensive part which can fail any time, due to complexity and relay quality which controls the motors, is the ignition board. Depends on model and brand you can expect cost between $400 and $900