Fast, Reliable Heating & Furnace Across Sunnyvale
Furnace repair in Sunnyvale typically runs $150–$700, while a full replacement on a standard residential system falls between $3,500–$7,500. Most calls in Sunnyvale’s 94086, 94087, and 94089 ZIP codes get same-day or next-day response. Call (855) 467-1888 for a free estimate.
We’ve been driving down Highway 101 to Sunnyvale for 16 years. Jason Trent, our owner and Field Supervisor, has crawled through enough attics in the 94087 ranch tracts to know which 1960s furnaces are still salvageable and which ones are pouring carbon monoxide into a family’s living room. Sunnyvale’s post-war housing stock isn’t a footnote for us. It’s the bulk of what we service. From the Lockheed-era ranches off Remington Drive to the worker cottages near Moffett Field in 94089, we know the ductwork, the failure patterns, and the parts-availability dead ends that catch less experienced techs off guard.
Why Stonegate Heating & Air California Is Sunnyvale’s Preferred Heating & Furnace Company
Our Heating & Furnace team has built a reputation in Sunnyvale on one thing: showing up with the right diagnosis and no runaround. Nearly 500 verified reviews at a 4.7-star average don’t happen by accident. They come from 16 years of Jason Trent supervising jobs personally, not dispatching whichever contractor is free that day.
Sunnyvale customers specifically mention our willingness to explain the repair-versus-replace math on aging equipment. In a market full of tech-industry homeowners who research before they call, that transparency matters. We don’t quote a replacement when a heat exchanger patch or gas valve swap will buy another three seasons.
Response time to Sunnyvale averages same-day for calls received before noon, next-day for afternoon requests. Emergency HVAC service is available for no-heat situations, failed ignitors on cold nights, and cracked heat exchangers leaking CO.
Our local knowledge runs deep. We know that a 94086 slab-on-grade ranch with original ductwork presents different challenges than a 94085 bungalow with a wall furnace. We know that Diablo wind events push Sunnyvale past 100°F, and that wildfire smoke season now lasts weeks, not days. That context changes how we size equipment and specify filtration.
Our Heating & Furnace Services in Sunnyvale
Furnace Repair
Most Sunnyvale furnace repair calls we handle fall into three categories: failed ignitors in aging systems, gas valves that won’t open fully, and blower motors straining against undersized return ducts. In 94087 and 94086, we regularly find 25- to 40-year-old furnaces that have been patched once already. We’ll tell you honestly if another repair is throwing good money after bad. Typical furnace repair in Sunnyvale: $150–$700.
Furnace Replacement
Replacement is where Sunnyvale’s housing stock gets interesting. Those 1950s–1970s ranch homes were built with furnace-only ductwork: 6-inch branch runs, trunk-and-branch layout in the attic, sized for heating loads that assumed no AC. When we quote a replacement, we’re often quoting a system integration problem, not just a box swap. Upsizing branch ducts, adding returns, or specifying a ductless complement can be the difference between a furnace that runs and a home that’s actually comfortable. Furnace replacement in Sunnyvale: $3,500–$7,500.
Furnace Tune-Up
A tune-up on a Sunnyvale system means checking heat exchanger integrity with a camera scope, testing gas pressure at the manifold, and inspecting blower amp draw against the nameplate. In wildfire season, we also evaluate whether your filter slot can handle MERV-13 or if the static pressure would choke the blower. Annual furnace tune-up: $80–$200.
Heat Exchanger Inspection & Replacement
This is the safety-critical one. Cracked heat exchangers in 94086 and 94087 slab-on-grade ranches are a pattern we’ve seen repeatedly, especially in homes that have changed hands as flips. The crack can be hairline and silent, leaking CO into living spaces through the plenum. We scope every heat exchanger we can access. If it’s cracked, we red-tag the unit and walk you through replacement options. Heat exchanger work: $150–$700.
Ignitor Replacement
Hot-surface ignitors fail predictably after 5–7 years in the dry Santa Clara Valley climate. In 94089’s older worker cottages with original floor furnaces, Robertshaw and similar pilot assemblies are often discontinued. We’ll check parts availability before quoting a repair, and we’ll tell you if a full system upgrade makes more sense. Ignitor replacement: $150–$700.
Gas Valve Repair
Gas valves stick, leak, or fail to modulate properly, especially on furnaces that have cycled through years of short-running due to oversized capacity or restricted airflow. We test manifold pressure, check for gas leaks at all joints, and replace only when the valve itself is the fault, not a symptom of a bigger problem. Gas valve repair: $150–$700.
What happens when you call
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A real person answersNo phone trees — you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Sunnyvale
Whatever brand is in your Sunnyvale home, we’ve likely worked on it. Our technicians are experienced with Carrier, Trane, Lennox, Goodman, Rheem, York, Daikin, Bryant, and American Standard. We carry common ignitors, gas valves, and blower components for Bryant and American Standard systems on our trucks, which means faster turnaround on Sunnyvale calls. For Daikin and Carrier systems, we maintain supplier relationships that get us next-day parts when something unusual fails. Nine brands, one team. No “we don’t service that” dead ends.
Common Heating & Furnace Problems We See in Sunnyvale Homes
- Cracked heat exchangers in 94086 and 94087 slab ranches. These homes were built with furnaces that ran hard for 30–40 years. The heat exchanger metal fatigues, cracks form between cells, and CO enters the supply air. We scope these during every tune-up and replacement quote.
- Failed floor-furnace ignitors in 94089 worker cottages. The small homes near Moffett Field and the old industrial corridor still run original wall or floor furnaces. Parts are discontinued. We check availability before quoting repair, and we’ll be direct if replacement is the only viable path.
- Diablo wind events overwhelming undersized systems in 94085. When temperatures spike past 100°F, 1.5-ton systems in older bungalows short-cycle or freeze up. Homeowners crank the thermostat, the system runs continuously, and the furnace blower never gets a break. We size replacements for the 99th percentile, not the median.
- Wildfire smoke degrading standard filtration. MERV-8 filters don’t catch PM2.5. We evaluate whether your furnace blower can handle MERV-13 or if you need a standalone air scrubber. This has become a near-standard add-on in Sunnyvale replacements since 2020.
Pricing for Heating & Furnace in Sunnyvale, CA
| Service | Typical Range in Sunnyvale |
|---|---|
| Furnace Repair | $150–$700 |
| Furnace Replacement | $3,500–$7,500 |
| Furnace Tune-Up | $80–$200 |
| Heat Exchanger Repair/Replacement | $150–$700 |
| Ignitor Replacement | $150–$700 |
| Gas Valve Repair | $150–$700 |
What moves you within these ranges? Parts availability for discontinued components, access difficulty in shallow crawlspaces or packed attics, and whether duct modifications are needed alongside the furnace work. In a 1958 ranch on Remington Drive (94087), we found a 60,000 BTU furnace with original sheet-metal trunk-and-branch ducts. The homeowner wanted AC, so we upsized the branch runs to 8 inches in the attic and installed a 3-ton Carrier condenser. The rear bedrooms now stay within 2°F of the thermostat setpoint instead of the previous 9°F delta. That job sat at the higher end because of the ductwork, but the homeowner avoided a future callback and a second contractor.
We don’t quote over the phone for replacement work. We inspect the existing system, measure the home, and run a load calculation. Estimates are free. Call (855) 467-1888 to schedule.
We Also Serve Cities Near Sunnyvale
Our service radius covers the full South Bay corridor. We regularly run calls to Mountain View, Santa Clara, Cupertino, and Los Altos from our dispatch. Each city has its own housing stock and climate quirks, but the same owner-supervised standard applies. If you’re in a neighboring city and found this page, the same team and the same pricing structure serve your area.
Serving Sunnyvale, CA — Our Local Coverage Area
We’re based in the Sunnyvale area and know this community well. Use the map below to see our service coverage — if you’re nearby, we can almost certainly help.
FAQs — Heating & Furnace in Sunnyvale
No, not if you want even cooling. The original 6-inch branch runs were sized for a 60,000 BTU furnace, not a 3-ton condenser. Back bedrooms will run 8–10°F warmer than the front of the house. The fix is upsizing branches in the attic or adding a ductless head. We’ve done this dozens of times in 94087. Call (855) 467-1888 and we’ll measure your ductwork during a free estimate.
Maybe, if the ignitor or thermocouple is still available. Many Robertshaw pilot assemblies for 1960s floor furnaces are discontinued. We check parts before quoting repair. If the component is obsolete, replacement is the only safe option. Call (855) 467-1888 — we’ll run the parts check and give you both numbers.
Your ductwork is almost certainly undersized for cooling. This is the most common call we get in Sunnyvale’s 94087 ranch tracts. The 6-inch branch runs can’t move enough CFM for a 3-ton condenser. We upsize to 8-inch branches or recommend a ductless mini-split for the hot zone. Call (855) 467-1888 — we’ll trace the airflow and show you the fix.
Standard MERV-8 filters won’t catch PM2.5 particles. We specify MERV-13 or add an air scrubber to most Sunnyvale replacements now. The catch: your blower must handle the static pressure. We test this during tune-ups and replacement quotes. If your system can’t take MERV-13 without straining, we’ll tell you and propose alternatives. Call (855) 467-1888 for a filter and blower evaluation.
Yes, but access matters. Slab-on-grade homes typically have the furnace in a closet, garage, or attic. If it’s in the attic, replacement is straightforward. If it’s in a tight closet with no plenum clearance, we may need to reconfigure the return or relocate the unit. We’ve replaced hundreds of slab-ranch furnaces in Sunnyvale. Call (855) 467-1888 — we’ll assess your specific layout during a free estimate.
Written by Jason Trent, Owner and Field Supervisor at Stonegate Heating & Air California, serving Sunnyvale and the South Bay since 2008.