A furnace tune-up in San Leandro has two jobs. The first is safety: making sure the burners light cleanly, the combustion gases leave through the vent, and the heat exchanger that keeps those gases out of your air is intact. The second is reliability: cleaning and testing the parts that most often fail on the first cold night, such as the flame sensor, the igniter and the blower. Both happen on the same visit, and the safety inspection is part of the price.
The safety inspection
- Burners and flame. A healthy gas flame is steady and mostly blue. Lazy, yellow or lifting flames point to dirty burners or an air or gas pressure problem.
- Venting. We check that the vent pipe is intact, sloped and connected, and that the furnace drafts properly. On furnaces that share a vent with the water heater, both are looked at.
- Heat exchanger. We inspect the parts of the heat exchanger that can be seen for cracks, rust-through and soot.
- Gas connections. The connections at the furnace are checked for leaks.
- Safety controls. The high-limit, rollout and pressure switches are tested, because they are what shut the furnace down when something goes wrong.
- Carbon monoxide. We check for carbon monoxide around the furnace and remind you to test your CO alarms.
Cleaning and reliability checks
- Clean the flame sensor; a coated sensor is the most common reason a furnace lights and then shuts off.
- Check the igniter for cracks and wear.
- Clean the burners if the flame calls for it.
- Inspect the blower wheel and motor, and measure the motor’s current draw.
- Check or replace the filter.
- On high-efficiency furnaces, clear the condensate trap and drain line.
- Measure the temperature rise across the furnace against the range on its rating plate.
- Run a full heating cycle from the thermostat.
What a tune-up can turn up
| Finding | What it means | Next step |
|---|---|---|
| Dirty burners | Uneven flame and a possible loud start | Cleaned on the visit |
| Coated flame sensor | Furnace may light and shut off | Cleaned on the visit |
| Worn igniter | Likely to fail in cold weather | Replacement offered with a price |
| Noisy or weak blower | Poor airflow, overheating, short cycling | Cleaning or furnace repair |
| Blocked condensate trap | Furnace shuts down on a high-efficiency unit | Cleared on the visit |
| Cracked heat exchanger | Combustion gases may reach the air you breathe | Furnace should not be run; repair or replacement |
Nothing beyond the tune-up is done without your approval. If a part needs replacing, you get the price first.
When to book
Early fall is best: September and October, before heating season starts in earnest in November. Furnaces that sat idle all summer show their weak parts on the first cold night, which is also when everyone else is calling. Many households pair a fall furnace visit with a spring AC tune-up, so each half of the system is checked before its season.
Between visits
- Change the filter regularly; in heating season, check it every month or two.
- Keep the area around the furnace clear. Hall closets and garages tend to fill up with boxes, paint, cleaning supplies and gas cans, none of which belong near a burner.
- If the furnace closet door has louvers, do not block them; many closet furnaces draw their combustion air through them.
- Test your carbon monoxide alarms and replace their batteries on schedule.
- Keep supply registers and return grilles open, even in unused rooms.
Cost and warranty
A furnace tune-up costs $89 to $149, and the safety inspection is included. The range depends on the type of furnace, where it is installed and how much cleaning it needs; an attic or crawlspace furnace takes longer than one in a garage. Some manufacturer warranties expect regular professional maintenance, so keep the record of each visit. Seniors and military households get 10% off.
Local notes
Many furnaces in San Leandro, San Lorenzo and Castro Valley sit in hall closets or garages of post-war homes, often sharing a vent with the water heater. Those shared vents, and the stored items packed around closet furnaces, are two of the things we look at most carefully. If you notice more dust in the house once the heat comes on, the filter and ducts are worth a look; see indoor air quality.