Furnace
The Blinking Light on Your Furnace Is Talking: How to Read Error Codes
The LED behind your furnace's panel window blinks a code. Count the flashes, check the door legend, and learn what common codes mean and which are DIY.
Formerly Adam & Sam Brothers RepairLake Forest Park · Heating
Furnace care for Lake Forest Park's older, wooded homes
Lake Forest Park has the oldest houses of any city we serve, many with ductwork reworked through several remodels. We repair gas and electric furnaces, plan replacements, and reach most addresses in 8–11 minutes by way of Ballinger Way.
- Built 1960–79
- About 37% of homes; only 9% since 2000
- Gas heat
- About 53% of homes; most others heat with electricity
- Older stock
- 35% built before 1960, including 12% before 1940
- $85 diagnosticBecomes part of the repair price when you say yes. If you pass on the repair, that visit is all you pay.
- Up to $18 offAny repair requested through the online form. The diagnostic itself is never reduced.
- No-charge site visitInstalls are quoted in writing, equipment and installation work in one number.
Ole Hanson laid out Lake Forest Park in 1912 with the rule that its natural beauty must be preserved, and the city still looks the part: winding streets, salmon creeks, and houses tucked beneath big trees on medium and large lots. It also has the oldest housing among the cities we cover. About a third of homes predate 1960, and only about 9% were built after 2000. Old houses mean furnaces in tight basements, ductwork patched over the decades and vent paths that have changed more than once.
Our Lake Forest Park work splits between two kinds of furnace. Gas furnaces, which heat about half the city, get the usual repairs: igniters, sensors, pressure switches and blowers. Electric furnaces get element and sequencer work, and when one is near the end, we study the house and write replacement or heat pump options with prices attached. Every job starts with a diagnosis and a written number, and nothing is replaced until you approve it. Because so many houses here have been remodeled piece by piece, we also note anything odd we see along the way, such as an abandoned flue, a disconnected return or wiring spliced in an attic, so you have a clear picture of the whole system and not just the part that failed.
What goes wrong with Lake Forest Park furnaces
Furnace runs, but the house never catches up on a cold night
- Likely cause
- Leaky or undersized ducts, a slow blower, or a failing heat stage
- What we do
- Measure supply and return temperatures, check blower speed, and look for disconnected runs
Gas burners light with a small bang
- Likely cause
- Delayed ignition from dirty burners or a misplaced igniter
- What we do
- Clean and align the burners, check igniter position, and test the gas pressure
Pressure switch code on a condensing furnace
- Likely cause
- Intake or exhaust blocked by leaves, needles or a nest
- What we do
- Clear the outdoor terminations, check the trap, and confirm the switch closes on good draft
Electric furnace hums, breaker holds, nothing heats
- Likely cause
- An open element or a failed sequencer
- What we do
- Test each heating stage, replace the open coil or relay, and check the wire insulation
Burners shut off after a minute or two, then relight
- Likely cause
- Dirty flame sensor, or a limit tripping on a clogged filter
- What we do
- Clean the sensor, check the filter and airflow, and test the limit switch
You smell gas
- Likely cause
- Possible leak inside the house
- What we do
- Leave first, then call PSE at 1-888-225-5773 or 911 from outdoors; we inspect after PSE gives the all-clear
Lake Forest Park houses and their heating history
Many Lake Forest Park houses have changed heating equipment more than once. A 1940s or 1950s home off Ballinger Way NE may have gained a gas furnace when PSE ran a main up the street, then picked up an electric furnace or baseboards in a later addition. In the basement we often find a newer gas furnace sitting on ductwork decades older than it, sometimes with the old masonry chimney still serving a gas water heater. Those details shape every replacement quote, because venting a new furnace correctly is where older houses hide extra cost. Lots along Lyon Creek and McAleer Creek also stay damp, and crawlspace furnaces in those low spots tend to show rust on cabinets and duct joints sooner. Basement ceilings in these houses are often low and crowded with plumbing, so we check the route for a new flue or PVC vent before we commit to a model.
The homes here that don't burn gas mostly heat with electricity, whether an electric furnace on ducts or baseboards in rooms added later. When an electric furnace nears the end, a heat pump with an air handler is usually the next step, and it brings cooling for summers like the one that brought the June 2021 heat dome. Gas households have a choice too: a new condensing furnace vented through the wall, or a heat pump paired with the gas furnace, which then runs only on the coldest days. Seattle City Light supplies the electricity in Lake Forest Park and PSE the gas; we check which City Light programs apply before we finalize a heat pump quote.
The city sits squarely in the Convergence Zone, and its tall trees pull down City Light lines when wind and wet snow arrive together. Furnaces stop when the power does, and the hills up toward Horizon View and Sheridan Heights can be slow after snow. We come in on SR 104 and SR 522 and plan around those climbs when the weather turns, so a cold morning call still gets a same-day visit whenever the roads allow. After an outage, give the furnace a few minutes once power returns; if it stays silent, check the breaker and the service switch, then call us. SR 522, the old Red Brick Road along the lake, is our usual way into the south end near Sheridan Beach.
Furnace costs in Lake Forest Park
Furnace repair in Lake Forest Park starts at $285. Igniters are the everyday job in the gas half of the city, while a control board on a furnace that has outlived a few remodels lands at the upper end. Replacing a failed electric furnace starts at $4,500, equipment and installation included; moving from electric heat to gas, or adding a heat pump, can bring venting, gas service or electrical work, which the written quote itemizes line by line. These figures show where pricing begins in our area and are not a quote. The real number follows the diagnosis and comes to you in writing. The site visit to measure for a replacement costs nothing.
- Flame sensor cleaning or replacementfrom $285
- Furnace igniterfrom $285
- Limit switchfrom $285
- Pressure switchfrom $285
- Sequencer or heat relayfrom $285
- Electric heat strip / elementfrom $285
- Furnace or air handler control boardfrom $425
- Gas valvefrom $425
- Blower motor (standard PSC)from $475
- Inducer motorfrom $550
- Blower motor (ECM / variable speed)from $850
- Diagnostic visit$85, included in the repair
Starting prices for the north Seattle area, 2026. The $85 diagnostic is included in any repair you approve, and the exact price is in the written estimate before work starts.
System, installed
- Gas furnace, 80% AFUEfrom $4,750
- Gas furnace, 95%+ AFUEfrom $6,500
- Electric furnacefrom $4,500
- Heat pump outdoor unit onlyfrom $5,250
Install prices start here, equipment and installation included, before any utility program. Multi-zone systems are priced after a visit. We do not charge for the site visit or the written quote.
Deciding on an older Lake Forest Park furnace
In a house this old, the furnace is often not the oldest part of the heating system. The ducts, the chimney and the wiring can all be decades older, and a good decision looks at all of them. If the furnace is under fifteen years old and the failure is an igniter, a board or a limit, repair it and move on. If it is past twenty and needs a heat exchanger or an inducer, replacement usually wins, and that is the moment to ask what the new equipment should be, rather than copying whatever was there before. A heat pump needs ducts that can carry enough air, so we check sizes before recommending one; where the ducts fall short, a ductless system for part of the house can fill the gap. With an electric furnace past twenty years, plan the replacement before the coldest week of the year; the earlier you start, the more options stay open, including a heat pump on the same ducts.
Common questions
Do you serve Horizon View and Sheridan Beach?
Yes, along with every other Lake Forest Park neighborhood. Most addresses are eight to eleven minutes from our Mountlake Terrace shop off-peak, by SR 104 and SR 522. Steep or narrow driveways are fine; just tell us where to park. Calls that reach us early in the day, Monday through Saturday, usually get a technician that same day.
Can you switch my electric furnace to gas?
When PSE gas is available at your street, yes. We quote the new furnace and its venting, and we tell you what gas service and electrical changes the switch also needs so nothing surprises you later. Many Lake Forest Park owners also price a heat pump before deciding, and we write both quotes during the same visit.
Why does my furnace thump when it lights?
A thump or small bang at ignition usually means gas is building up for a moment before it lights, often because the burners are dirty or the igniter has shifted. It is worth fixing soon, since it stresses the heat exchanger. Turn the furnace off if the bang is loud, and call us to clean and adjust it.
Will a heat pump work with ductwork from the 1950s?
Sometimes. Heat pumps move more air at lower temperatures than a gas furnace, so small or leaky ducts can limit them. We measure duct sizes and static pressure before quoting. If the ducts fall short, sealing a few runs or adding a ductless head for one area often solves it without tearing into walls.
What do I do if I smell gas?
Leave the house at once and do not operate switches, the thermostat or the garage door on the way out. From outside, call PSE at 1-888-225-5773 or 911. Once they have made the line safe, call us and we will inspect the furnace and its gas connections and write a price for any repair.
Talk to Adam & Sam
Ring (425) 570-9520 with the furnace nameplate in view, or book online, note its model number in the form and save up to $18 on the repair. Approve the job and the $85 diagnostic is counted inside the repair price; measuring for a new furnace or heat pump is at no charge.
From Sam’s repair notes
Furnace
Furnace Running But Blowing Cold Air? Five Causes, From No-Cost to 'Call Now'
Fan-ON settings, flame sensor dropouts, overheating limit trips, dead igniters and duct leaks all blow cold. How to tell which one you have.
Furnace
Furnace Clicks But Won't Ignite: Igniter, Flame Sensor and the Pressure Switch Chain
No-ignition calls follow a chain: inducer, pressure switch, igniter glow, gas valve, flame sensor. Where each link fails and what the clicking means.
Schedule a repair
Request a visit from Adam & Sam
Send the basics and we call you back with an arrival window, most days the same morning.
- $85 diagnostic Becomes part of the repair price when you say yes. If you pass on the repair, that visit is all you pay.
- Up to $18 off Any repair requested through the online form. The diagnostic itself is never reduced.
- $10 off A second appliance’s diagnostic when we check it during the same trip.