Typical maintenance schedule for residential furnace (2-stage)

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AG-WindyCity

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Beyond the standard annual check for flame rollout and carbon monoxide, the manufacturer recommends additional maintenance. I’ve read the maintenance instructions to understand the work needed. I understand that maintenance is based on conditions and usage, rather than strict time and that usage depends on location - we live in the suburbs of Chicago, so typical furnace usage is November through March. Fairly light usage November, December, and March. Heavy usage in January and February. Family of 5; no pets. Based on this information, I’ve created the schedule below with questions, and would appreciate forum feedback and insights. I don't think it matters, but the furnace is a Residential Carrier Performance 2-stage 80kBTU; 59TP6B. Thank you.

Typically every 2 years?
Clean flame sensor with fine steel wool (0000 grade). Check HSI resistance at room temperature 40-70 ohms; replace if necessary; no maintenance.

Typically every 4 years?
Remove and clean burner with brass brush and vacuum.

Typically every 5 years? (I’m using a MERV 11 filter, and monitor pressure drop to know when to change.)
Pull and vacuum blower motor and wheel; do not disturb balance weights.

Typically every 10 years? (I’m using a MERV 11 filter, and monitor pressure drop to know when to change.)
Pull, disassemble, and clean blower wheel - wash with mild soap and water; do not disturb balance weights.

Typically every X years???
Flush Collector Box and Drainage System

Typically every X years??? Or is this typically a reactionary maintenance action for a clog?
Remove and Clean Condensate Trap

Typically every X years???
Clean Primary Heat Exchanger
 

Guzzle

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There's a method for figuring the repair/replace breakpoint, originally for vehicles. The $ value of your unit decreases year by year & the repair costs increase year by year. I'll post back if I can find it.
 

kok328

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The manufacturers owners manual should outline the maintenance points and schedule, much like a car's owners manual.
 

Guzzle

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My spreadsheet for doing this is giving me weird answers, so. . .

"A generally good rule of thumb: If the maintenance cost is over 50% of the value, that's a purchase. If it's less than 50% of the value, that's a repair."

BTW, I've never had to repair due to not maintaining.
 

Guzzle

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Assumed new furnace costs $4K
& over 15 years the value drops to $0 in a straight line.
Anybody with more realistic numbers for this, please chime in.

Cumulative cost for maintenance & repairs starts at $100 at the end of the first year
& goes up 10% each year.

15th year maintenance = $380 for the end of that year
& cumulative maintenance cost by the end of that year = $3200.

At 7-1/2 years the cumulative maintenance = 1/2 the furnace value = ~$1000 and so replace at 7-1/2 years.

At 15 years the cumulative maintenance = the furnace value and so replace at 15 years.

BTW, we're at 40 yrs & may be spent $1200, total, but I fix it myself.
 
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