Filters in Los Angeles: the questions that come up
The filter is the one maintenance item every LA household controls, and fire season changes the answer.
What MERV rating during fire season?
smoke and ash
MERV 13 captures the fine smoke particles that MERV 8 does not — but only if the system was designed for the extra resistance. Most LA retrofits, on ducts sized for a 1958 furnace, were not. A MERV 13 filter on an undersized return drops airflow, freezes the coil in September and trips the furnace limit in December. The answer: a MERV 11 in a 1-inch slot, or a 4-inch MERV 13 media cabinet installed by the contractor, which has the surface area to carry the rating without choking the blower. Ask at the tune-up.
How often?
less than you think, then more
LA systems run fewer hours than in any other metro we serve, so a 1-inch filter can go 60–90 days most of the year. During a smoke event, check it weekly; a filter can load in days. Run the fan continuously with a good filter during smoke — it is the cheapest air purifier in the house.
Where is it?
the LA-specific answer
In a retrofit, sometimes nowhere. Systems added to prewar houses in Pasadena, Highland Park and the Valley occasionally have no filter rack at all, or a filter grille in a hallway ceiling that nobody has opened in years. Finding and fixing that is a tune-up item here and nowhere else.
The 30-year furnace and the combustion check
Los Angeles has the oldest heating equipment of the five metros: wall furnaces in courtyard apartments across the basin, floor furnaces in Craftsman homes, 1970s closet furnaces in Torrance and Downey tracts. A fall maintenance visit on any of them is mainly a safety inspection, and it must include:
- A combustion analysis at the supply register — carbon monoxide in the air the furnace delivers — not a flashlight look at the exchanger.
- Draft and spillage test at the flue; old metal flues in retrofit closets backdraft.
- Thermocouple and pilot service on standing-pilot units; gas pressure at the manifold.
- On a wall furnace: the vent connection and the grille clearance, because a wall furnace that fails vents into the room.
An honest tech will sometimes recommend not relighting a furnace. That is the visit doing its job.
Low runtime, three climates
Los Angeles averages about 1,240 heating degree days and 800 cooling degree days a year (NOAA normals for the city; climate zone 3B). The air conditioner in a Santa Monica house may run a few dozen hours a year; the one in a Van Nuys house runs every afternoon from July to September. The Valley — Van Nuys, Burbank, Glendale, Pasadena — gets a real spring cooling tune-up: charge, capacitor, coil. The coast gets a check that the system still starts. Maintenance priced as if every LA house were the Valley is overpriced for half the county.
Where in LA County
Contractors cover the City of Los Angeles and the independent cities: Long Beach, Torrance, Inglewood, Downey and Whittier; Pasadena, Glendale and Burbank along the foothills; Santa Monica on the coast; Van Nuys, Sherman Oaks, North Hollywood and the San Fernando Valley. The visit changes with the house: prewar homes in Pasadena, Highland Park and Long Beach get the furnace safety check and a search for the filter; 1950s–70s tracts in Torrance, Downey, Whittier and Reseda get the closet furnace and the R-22 condenser both checked, with an honest word about the refrigerant; Valley homes with attic retrofits get the real cooling tune-up.
The Los Angeles maintenance calendar
Later and lighter than in the hot metros:
- April–MayCooling tune-up — Valley and inland homes. Charge, capacitor, coil, static. Coastal homes: a start-up check.
- July–SeptemberPeak in the Valley; contractors on emergency calls. Filter monthly. Coil rinse after any smoke.
- OctoberSanta Ana winds and fire season. Filter weekly during smoke; FAN on with a good filter.
- NovemberFurnace safety check, before the first cold night after Thanksgiving. Combustion analysis on anything old, which is most of them.
Licensing, permits and utility programs
Maintenance needs no permit anywhere in LA County; only a replacement does, through the Los Angeles Department of Building and Safety inside the city or the equivalent in Long Beach, Pasadena, Glendale, Burbank, Torrance and Santa Monica. Any HVAC work above a small dollar threshold must be by a contractor holding a C-20 license from the Contractors State License Board; on a 30-year-old gas furnace, that is not optional. No utility pays for a tune-up; when the fall visit turns into a replacement conversation, LADWP's per-ton heat pump rebate inside the city and SoCalGas's furnace rebate are on the LADWP and SoCalGas sites, and the Los Angeles installation page walks through which applies.
What maintenance costs in Los Angeles
LA labor is the highest of the five metros. The furnace safety check is the one to pay for; the cooling tune-up is worth it in the Valley and inland.
- Furnace safety check, standalonecombustion analysis, draft, thermocouple, gas pressure
- $130–$280
- Cooling tune-up, standaloneValley and inland; charge, capacitor, coil, static
- $120–$270
- Wall or floor furnace servicepilot, thermocouple, vent, grille
- $140–$300
- Two-visit planspring cooling, fall furnace
- $240–$460 / yr
- Premium plantwo visits, priority during heat waves, 10–20% repair discount
- $400–$700 / yr
- 4-inch media filter cabinetinstalled; carries MERV 13 without choking the blower
- $250–$600
- Post-smoke visitcoil rinse, filter, blower amps
- $110–$240
If the fall check finds the exchanger gone or the pilot that will not stay lit, the Los Angeles furnace repair page has the costs. The full tune-up checklist and plan comparison for any metro are on the maintenance page.