Pre-Season Furnace Tune-Up Checklist

Every fall, before the first hard freeze, we run pre-season furnace tune-ups across the Twin Ports. Here is what we actually check, in the order we check it, and why the order matters.

1. Combustion analyzer reading

First thing on the truck, last thing before we leave. We sample the flue gases to measure CO, O2, stack temperature, and combustion efficiency. This is the single most important number on a gas furnace. If CO is high, the unit is burning rich or has a venting problem. If O2 is high, it is starving for gas. Both are fixable, both are invisible without the right instrument.

2. Static pressure

A manometer across the supply and return tells us whether the duct system is restrictive. High static pressure cooks blower motors, kills capacitors, and shortens furnace life. Most homes we test sit between 0.8 and 1.2 inches of water column, where they should be at 0.5. A new filter is sometimes all it takes. Sometimes we need to talk about duct sizing.

3. Flame sensor, ignitor, pressure switches

These are the three components that account for 70 percent of no-heat calls in winter. We clean the flame sensor (it gets sooty and stops conducting microamps to ground). We inspect the hot surface ignitor for hairline cracks. We test pressure switches for the right open-close points. If anything is borderline, we replace it before it fails in January.

4. Burners, heat exchanger, blower wheel

Burners get pulled and visually inspected for rust, scale, or carbon. The heat exchanger gets inspected for cracks (this is the safety-critical one, a cracked heat exchanger leaks CO into your home). The blower wheel gets cleaned if dirty, because a dirty wheel cuts CFM by 20 to 30 percent.

5. Condensate, gas pressure, electrical safeties

Condensate drain inspected and flushed (clogged condensate is a top-five winter callback). Gas inlet and manifold pressure measured against the nameplate. Limit switches, rollout switches, and the door switch tested. Every safety circuit that protects you and your house.

What it costs

A full pre-season tune-up is $99 for non-members, free for Comfort Club members. Add a humidifier service or a filter swap on the same visit and we will roll it in at a member discount.

When to schedule

September or October. Before the first cold snap pushes everyone to call at the same time. We start booking fall tune-ups in mid-August. Call us at (218) 729-2789 to get on the list.

Need a hand? Call us at (218) 729-2789 or request service online.