Furnace Tune-Up and Safety Inspection in Pittsburgh, PA

What a furnace tune-up covers, step by step

Every tune-up follows the same sequence so nothing gets skipped. Some steps apply only to certain furnaces, such as the condensate checks on 90% and higher units or the draft test on chimney-vented ones.

Combustion and carbon monoxide testing

This is the part of the visit that makes it a safety inspection. With the furnace at steady fire, the technician inserts the probe of a calibrated combustion analyzer into the flue and reads carbon monoxide, oxygen and flue temperature. The numbers show whether the burners are getting the right mix of gas and air.

High CO in the flue usually points to dirty burners, low combustion air, incorrect gas pressure or a partly blocked vent. The technician also checks for CO in the supply air at the plenum or a nearby register, and at the draft hood on older units. A rise in the house air while the furnace runs is a serious finding and the reason the inspection exists.

Heat exchanger, burner and flame sensor inspection

The burners come out or are cleaned in place to remove rust scale, dust and spider webs, which are common in damp Pittsburgh basements. The technician then watches the flame: steady, blue and inside the heat exchanger openings is what you want. Yellow tips, lifting flames or flames that bend when the blower starts need a closer look.

The heat exchanger is inspected with a light and, where access allows, an inspection camera. Most tune-ups find nothing wrong. When a crack or hole is found, the furnace may have to be shut down, and our page on red-tagged furnaces explains what happens next and how to get a second opinion.

The flame sensor is cleaned and its signal measured in microamps with a meter, then compared with the manufacturer's spec. A low reading means the furnace may light and shut off after a few seconds on a cold morning. The hot surface ignitor is checked for cracks and resistance, since a weak one often fails in the first week of real cold.

Filters, blower and airflow

Airflow problems shorten a furnace's life quietly. The filter is checked and replaced, and the technician confirms it is the right size and seated without gaps. The blower wheel is inspected for dirt buildup, the motor amperage is measured, and the run capacitor is tested against its rated microfarads.

Temperature rise ties it together: the difference between return air and supply air, compared with the range printed on the furnace's rating plate. A rise above the range means too little air, which overheats the heat exchanger. That is common in pre-war houses where ductwork was retrofitted later with undersized returns. If the blower or capacitor is failing, see furnace blower motor repair.

• Check the filter monthly in winter; change it when it looks gray.
• Keep supply registers and return grilles clear of furniture and rugs.
• Do not close more than a couple of registers in unused rooms.

Furnace maintenance you can do yourself, and what needs a technician

A tune-up doesn't replace the simple things you can do between visits, and those simple things don't replace a tune-up. Here's where the line sits.

Homeowner tasks

• Check the filter monthly during the heating season and change it when it looks gray
• Keep supply registers and return grilles open and clear
• Replace thermostat batteries each fall
• Test carbon monoxide alarms and replace any past the date on the back
• Keep boxes, laundry and paint cans away from the furnace and water heater
• On a high-efficiency furnace, keep the outside PVC pipes clear of snow and leaves

Technician tasks

• Combustion analysis and carbon monoxide testing
• Gas pressure measurement and leak checks at the furnace
• Heat exchanger and burner inspection
• Flame sensor microamp and ignitor resistance readings
• Safety control tests: high limit, rollout and pressure switches
• Draft test on chimney-vented furnaces

Which filter to buy

Use the size printed on the edge of the old filter, or the size listed in the furnace manual. A higher MERV rating catches finer dust but also restricts more air, and a very dense filter in a furnace with a small return can trip the high limit. Check what the furnace manufacturer allows before moving to a high-MERV filter, and ask the technician to measure static pressure if you do.

Vent and chimney check for older Pittsburgh homes

Venting is where Pittsburgh homes differ most from newer markets. Many 80% furnaces in the city and inner-ring suburbs still exhaust into brick chimneys that were built for coal or an older, hotter appliance.

Chimney-vented furnaces

The technician checks draft with a gauge or smoke test, inspects the flue pipe for rust, slope and loose joints, and looks at the chimney base or clean-out for fallen brick and mortar. An unlined masonry chimney may need a liner, and a weak draft on a cold day can mean exhaust spilling back into the basement.

High-efficiency furnaces with PVC venting

On 90% and higher furnaces the technician checks the intake and exhaust terminations outside for nests, leaves and low clearance to the snow line, then clears the condensate trap, flushes the drain and confirms any condensate pump works. These are the furnaces that quit in a deep freeze when the drain line freezes.

When to book: before the first cold snap

The best window in Pittsburgh is September through early November. Scheduling is easier, and if the tune-up turns up a weak ignitor, a failing capacitor or a cracked heat exchanger, there is time to fix it before you depend on the furnace every night. EPA guidance supports having furnaces, flues and chimneys inspected every year, and many manufacturers recommend annual professional service.

Once the first hard freeze arrives, technicians switch to no-heat calls and maintenance gets pushed back. A furnace that has sat idle since April also tends to show its weak parts on the first cold morning, which is why so many no heat repair calls come in the same week each fall.

We book tune-ups across the city and our service areas, including Penn Hills, Ross Township and Bethel Park. Every HVAC technician we send is licensed where Pennsylvania requires it, and insured.

What a furnace tune-up costs, and what to ask before you book

We don't publish a tune-up price, because what's included varies and so do the furnaces. You hear the price before the visit is booked and confirmed. These are the questions that make two tune-up prices comparable:

• Is combustion and carbon monoxide testing included? It's the safety half of the visit, and some low-priced tune-ups skip it.
• Is a filter included, and which size and rating?
• Does it cover the condensate trap and drain on a 90% or higher furnace?
• What happens if a repair is found? A good answer is a separate price for the repair, given before any work starts.
• Will you get the readings in writing? Carbon monoxide, temperature rise, gas pressure and flame-sensor microamps make next year's visit faster and more useful.

Access matters too. A furnace in a tight closet or under the basement stairs takes longer, and an older furnace with a standing pilot or a sooty burner may need more cleaning. For what common repairs involve if the tune-up finds one, see our Pittsburgh furnace repair cost guide.

What a tune-up does not fix, and when it turns into a repair

A tune-up cleans, adjusts and tests. It does not include replacement parts, chimney liners or ductwork changes. When the technician finds a part that is failing or out of spec, you get an explanation and a firm price before any repair, and you decide whether to go ahead now or later. Ask for the readings in writing, including carbon monoxide, temperature rise, gas pressure and flame-sensor microamps. They become the baseline for next year's visit.

• Small repairs often done the same visit: flame sensor, ignitor, capacitor, condensate trap or drain line.
• Repairs that may need a second visit: inducer or blower motor, control board, gas valve.
• Findings that change the plan: a cracked heat exchanger or failed venting, which may lead to a shutdown or a furnace replacement.

For a sense of what common repairs involve, see our Pittsburgh furnace repair cost guide. If the furnace stops before your appointment, try the basic furnace checks first.