Furnace Repair in Sonoma, CA

What breaks on furnaces around here?

Hot surface igniters top the list. They are brittle, they degrade with every cycle, and they crack from careless handling during unrelated service. Flame sensors run a close second, and a sensor gets cleaned rather than replaced unless it is physically damaged. After that: inducer motors and their bearings, blower motors and run capacitors, pressure switches and their hoses, condensate traps, and low-voltage wiring chewed up by rodents in a crawlspace.

Control boards fail less often than they get blamed. A board that keeps dying is usually being killed by something else, such as a shorted thermostat wire or a motor drawing far more current than it should. Two other failures deserve separate treatment: high limit switches rarely fail, they trip, and they trip for a reason worth finding; heat exchangers do fail, and that one ends the repair path, because a compromised exchanger can put combustion products into the air you breathe.

There is a Sonoma wrinkle here. The valley runs hot through summer, so the blower in most local systems carries the cooling season as well as the heating season, accumulating run hours a heating-only climate would never impose. That is why blower components here often fail before the burner side shows any age. If your cooling has also been weak, the two problems are frequently one problem, and our AC repair work in Sonoma starts at the same air handler.

When a unit clears all four, we repair it and say so plainly, even when a replacement quote would have been the easier sale. When it fails the combustion check, replacement is not a recommendation, it is the only correct answer.

What decides this more often than the furnace itself?

Static pressure. It is the most useful number on a furnace call and the one most rarely taken.

Every furnace is rated to move its design airflow against a specific amount of duct resistance, and that rating is printed on the unit. We measure the real figure with a manometer at the supply and return sides of the air handler. When it runs well past what the equipment was built for, the blower cannot deliver rated airflow. Less air across the exchanger means it runs hotter than intended, temperature rise climbs beyond the manufacturer's range, the high limit starts interrupting cycles, and the motor spends its life fighting the duct. All of that shortens equipment life and arrives eventually as a repair bill.

The causes are ordinary and physical: one undersized return trying to feed a whole house, a filter grille too small for the air it must pass, flex duct crushed where it turns under a floor, registers closed off in unused rooms, or a cooling coil dropped into an existing cabinet years later without anyone resizing the duct to suit it.

This is where converted Plaza-era housing gets expensive if it is ignored. A home that started with a gravity heater and got forced air added decades later usually has return capacity that was fitted rather than engineered. Correcting airflow is often smaller than the second premature failure it prevents, and it belongs in any serious conversation about heating and cooling work in Sonoma.

Who issues the permit here, the city or the county?

It depends on which side of the city line you are on, and that trips people up constantly in this valley.

Inside city limits, the City of Sonoma Building Division handles it, taking plan submittals through its online portal and reporting more than 600 building permits and more than 900 plan reviews and 1,900 inspections a year. Outside those limits, in the Springs communities and on the valley-floor and hillside properties beyond them, the authority is Permit Sonoma, the county's permit and resource management department. Same valley, different department, different process.

Scope decides whether a permit is needed at all. Swapping a wear component on an appliance that stays in place is service work. Replacing the appliance is permitted work, and we file for it rather than leaving it to you. An unpermitted furnace discovered during a resale inspection is a far larger problem than the permit ever was.

Replacement also puts the job under California's energy standards. The 2025 Building Energy Efficiency Standards took effect January 1, 2026, per the California Energy Commission, and a change-out in an existing home is an alteration under them. Which measures attach depends on exactly what is being replaced, so we confirm that against the current standard before the application goes in.

Is the air district going to force me off gas?

Not this year, and not for a repair. Here is what the rule actually says.

Sonoma sits fully inside the Bay Area Air Quality Management District, which is not true of the whole county: the northern Sonoma County cities fall under a separate district entirely, as Sonoma County's air quality districts page sets out. Being fully inside BAAQMD means Regulation 9, Rule 4, Nitrogen Oxides from Fan Type Residential Central Furnaces applies at your address. The district's Board adopted amendments to that rule on March 15, 2023.

The mechanism matters more than the headline. This is a point-of-sale standard on new equipment, not a ban on the appliance in your closet.

So repairing your furnace is unaffected, and keeping it is unaffected. What the rule shapes is the equipment you will be able to buy once this one is finished, and implementation is still being worked through, so we verify the requirement in force when we write a replacement scope rather than quoting a date from memory. If your unit has a few seasons left, a sound repair keeps your options open while that settles. If it failed the combustion check, you are choosing equipment now, and a heat pump in Sonoma becomes a real candidate. That makes the panel a live question, since electric heating equipment needs capacity your service may not have spare, and so an electrical panel upgrade in Sonoma often gets priced alongside it.

Is there rebate money for any of this?

Not for repairs. Incentive programs attach to installing qualifying equipment, so a service call falls outside them. On the replacement side, the picture in Sonoma is narrower than most published advice suggests.

Sonoma Clean Power is the community choice energy provider here, which makes this county's incentive landscape different from Marin's and Napa's. SCP rebates qualifying heat pump heating and cooling systems, with one exclusion that matters on a furnace page: a heat pump paired with a gas heating element does not qualify. It also runs an enhanced heat pump water heater rebate for a limited period, after which that rebate continues only for customers enrolled in the CARE or FERA bill discount programs.

Will my furnace run during a Public Safety Power Shutoff?

No, and that surprises people who assume gas heat is independent of the grid. A modern furnace needs line power for the blower, the inducer motor, the igniter, and the control board. Gas at the meter produces nothing without electricity behind it.

That matters in this valley specifically. The hills around Sonoma carry real wildfire exposure and see PG&E Public Safety Power Shutoffs, so the scenario is not theoretical. If keeping heat through an extended outage is a requirement rather than a preference, the answer is a backup power conversation. We are a Certified Generac Generator installer, and standby generation, transfer switching, and the service capacity behind it fall under our electrical work in Sonoma. Scope it together, because the transfer equipment and the panel work are one project.

What should I be doing between service visits?

Filters first, and more often than the packaging suggests. Because the same blower carries your cooling months here, the filter loads year-round rather than seasonally. Wildfire smoke accelerates that sharply: a filter that looked serviceable in early autumn can be strangling the system a few weeks later.

Resist upgrading filter density without checking what the system can pull through. A high-MERV filter in an undersized grille raises static pressure and manufactures the exact overheating problem described further up this page. Leave supply registers open too, since closing off rooms to concentrate heat drives limit trips that cost more than the heat saved. Keep the space around the appliance clear, and never stack storage against a combustion air opening.

Book service before heating season rather than during it. A real annual visit includes combustion analysis, flame sensor cleaning, inducer and condensate checks, blower wheel inspection, a gas pressure reading, flue and vent inspection, safety switch verification, and a static pressure measurement so there is a trend line for next year. That last one separates diagnosis from a look. Our maintenance program keeps the cadence from slipping. Put working carbon monoxide alarms on every sleeping level and test them, regardless of how new the furnace is.

Which parts of the valley do you work in?

All of it. Inside the city, that means the Plaza and the older residential blocks around it, where tight equipment closets and retrofit ducting are the norm. North of the city line we cover Boyes Hot Springs and the wider Springs area, where permitting runs through the county. Beyond that, the valley-floor and hillside properties with long duct runs and detached structures.

Every truck runs from our Petaluma headquarters, a short trip over to the valley. The full local picture is on our Sonoma service page, and the wider view is on our Sonoma County heating and cooling page.

How do I tell a competent furnace contractor from a salesperson?

Ask for numbers. A technician who diagnosed your furnace properly can tell you the static pressure, the temperature rise across the exchanger, the gas manifold pressure, and what the combustion analyzer read. A diagnosis with no measurements behind it is a guess, however confident it sounds.

Ask which component failed, by name, and ask to see it. Ask whether the finding was confirmed by test or inferred from a symptom. Treat a first-visit heat exchanger condemnation with no combustion analysis and no visual evidence as a claim that needs backing, because it is the shortest path from a service call to a replacement quote.

Ask who pulls the permit when work crosses into replacement, and what happens if the repair does not hold. Then check license class and current status through the Contractors State License Board: C-20 covers HVAC, C-10 covers electrical, C-36 covers plumbing, and we hold all three. Ongaro & Sons has served the North Bay since 1932, is Diamond Certified, holds a BBB A+ Rating, and is a Trane Comfort Specialist, a Mitsubishi Diamond Contractor Elite. Our company background covers the rest.

What North Bay homeowners say

Two reviews that describe how we handle the repair-or-replace call: