Furnace Repair Draper UT | Draper Heating & Air Conditioning

Furnace Repair in Draper, Utah

Furnace repair in the south Salt Lake Valley comes in two varieties. The first is a legitimate diagnostic call: the furnace is not working, there is a measurable cause, and the repair is what the diagnosis supports. The second is a call that arrives after another contractor has already been out, condemned the furnace without documented evidence, and quoted a replacement that is not warranted by the system’s actual condition.

We see both regularly. The second is expensive for homeowners and profitable for contractors willing to skip borescope inspection and combustion analysis. Our repair process is measurement-first: we document what the instruments show before we quote anything. If the furnace needs repair, we say so and quote the repair. If it needs replacement, we say so and explain why, with the combustion analysis printout and borescope findings to support it. If it was condemned incorrectly by a prior contractor, we say that too, with the same documentation. The $89 diagnostic fee is the cost of finding out which situation you are actually in.

Our Furnace Repair Diagnostic Process

Step 1 — System History and Visual Inspection

Before instruments come out, the technician reviews any available service history, notes the furnace model, serial number, and approximate age, and performs a visual inspection covering:

  • Filter condition at arrival (a severely restricted filter causes high limit trips and intermittent heating that can look like a failed limit switch, flame sensor, or control board on initial symptoms)
  • Visible error codes on the control board LED (most modern furnaces from 2005 onward have LED fault code sequences; we record the code and cross-reference it against the manufacturer’s error code documentation before any disassembly)
  • Condensate drain condition on 90%+ AFUE units (a partially blocked condensate drain causes pressure switch trips that produce intermittent no-heat lockouts; it is the single most common cause of furnace “failure” calls on condensing units in the south Salt Lake Valley and is corrected by a $45 drain cleaning, not a $280 pressure switch replacement)
  • Visible venting integrity: disconnected vent connectors, blocked vent terminals (especially at SunCrest and Traverse Ridge where ice dam formation or heavy snow can block PVC vent terminations), and evidence of exhaust gas recirculation from nearby vent terminations
  • Gas valve and burner condition: pilot light or hot surface igniter condition, burner flames on a visual inspection (blue, stable flames with minimal yellow tipping are normal; orange flames, severe yellow tipping, or flames rolling toward the heat exchanger indicate combustion problems)

Step 2 — Combustion Analysis

Every furnace diagnostic call includes a combustion analysis at steady-state operation using a Testo 320 Basic flue gas analyzer. The combustion probe is inserted into the flue gas sampling port (or through the draft hood on Category I appliances) after the furnace reaches steady-state operation, typically 3–5 minutes after ignition.

We measure and record:

  • CO (carbon monoxide) in the flue gas, air-free: Target under 100 ppm. A reading above 200 ppm air-free causes us to shut the furnace down and investigate the cause before it is returned to operation. Common causes of elevated CO in the south Salt Lake Valley: altitude derate was never performed (rich-burn combustion producing incomplete combustion), cracked heat exchanger allowing flue gas dilution with combustion products, blocked flue gas recirculation at the burner head, or a gas-air mixture problem from a partially blocked burner orifice.
  • O₂ (oxygen) in the flue gas: Target 5–9% for a properly functioning gas furnace. O₂ below 4% indicates a rich mixture (excess fuel, insufficient air) — the classic signature of a furnace that was never altitude-derated at installation. O₂ above 11% indicates an excess-air condition, typically from dilution air infiltration through a draft hood or a leak in the vent connector.
  • Stack temperature: Compared against manufacturer specification for the furnace model at the current firing input. Stack temperature significantly below spec may indicate a heat exchanger with reduced surface area from internal scale buildup or a cracked exchanger allowing return air dilution. Stack temperature significantly above spec may indicate a restricted secondary heat exchanger on condensing units or a high-limit condition in development.
  • CO in ambient air: A Bacharach MGS-150 or equivalent CO detector is placed at the return air grille to measure ambient CO concentration in the return air stream. Any CO above the ambient background (typically 0–2 ppm in a well-maintained home) in the return air strongly suggests a cracked heat exchanger allowing flue gas into the conditioned air stream. This is the measurement that matters for occupant safety — CO in the flue gas stays in the flue; CO in the return air reaches the occupants.

Step 3 — Electrical and Component Diagnostics

Based on the fault codes and visual findings, we proceed to targeted component testing:

  • Inducer motor: Amperage measurement against nameplate FLA, shaft bearing condition (axial and radial play), and draft proving sequence timing. An inducer that starts but fails to build adequate draft within the manufacturer’s proving time trips the pressure switch and prevents ignition. Common causes: blocked condensate drain (most common), partially blocked flue terminal from ice accumulation at SunCrest, failed inducer motor bearing.
  • Pressure switches: Continuity test with the inducer running. A pressure switch that fails to close with the inducer running at rated speed (and the condensate drain confirmed clear) is a failed pressure switch. A pressure switch that fails to close because the inducer is not building adequate draft is a symptom of a blocked drain or blocked vent, not a failed switch. We distinguish these before quoting a part.
  • Hot surface igniter or pilot assembly: Hot surface igniters (silicon carbide or silicon nitride) are tested for resistance per manufacturer specification. A silicon carbide igniter with resistance above 100Ω is typically approaching end of life. A silicon nitride igniter is tested for open circuit. Pilot assemblies are inspected for thermocouple or thermopile output voltage under flame.
  • Flame sensor: Flame current measurement with a microamp meter. A clean stainless steel flame sensor in a properly burning furnace produces 1.5–5 microamps of flame current. A flame sensor producing less than 0.5 microamps causes the control board to shut down the gas valve on a false “no flame” signal after the ignition attempt. Flame sensor cleaning (fine steel wool or emery cloth, 30 seconds of work) restores original microamp output in most cases. We clean before quoting replacement.
  • Control board: Control board diagnosis is the last step, not the first. Most furnace control board “failures” are actually flame sensor issues, pressure switch issues, or condensate drain issues that manifest as control board fault codes. A board that shows fault code 13 (pressure switch stuck open) is not a failed board — it is a board correctly reporting a pressure switch or inducer problem. We do not quote control board replacement based on fault code alone without ruling out the upstream causes the code is reporting.
  • Gas valve: Manifold pressure measurement at the gas valve outlet, compared against the manufacturer’s rated manifold pressure and against the altitude-corrected target for the installation elevation. A gas valve producing manifold pressure within spec is a functioning gas valve. A gas valve producing manifold pressure outside spec may have an internal regulator problem or may have been previously set to the wrong specification by a prior technician who did not apply the altitude correction.
  • Blower motor: Amperage measurement against nameplate FLA, belt condition on belt-drive units, blower wheel cleanliness (a dirty blower wheel on a direct-drive motor draws above FLA and reduces airflow simultaneously), and bearing condition on direct-drive units through shaft resistance to manual rotation with power disconnected.

Step 4 — Heat Exchanger Inspection

For furnaces over 12 years old, for furnaces producing elevated CO in the flue gas, for furnaces where the combustion analysis shows ambient CO in the return air, and for any furnace that another contractor has condemned on the basis of a “cracked heat exchanger,” we perform a borescope inspection of the heat exchanger.

The borescope (a flexible fiber-optic camera with LED illumination, 5.5mm probe diameter) is inserted through the burner access panel into each heat exchanger cell in sequence. We examine the full visible length of each cell: the burner end, the mid-section, and the outlet end where the cell transitions to the inducer section. We document each cell with still photos and video where findings support it.

What we look for:

  • Cracks: Visible fractures in the heat exchanger wall, typically at stress concentration points (weld seams, bends, the area around the burner flame contact zone). A crack that is visible under borescope and accompanied by elevated ambient CO in the return air is a confirmed failed heat exchanger. The appropriate response is furnace replacement, heat exchanger replacement on units where replacement parts are available, or continued operation with daily CO monitoring while the homeowner arranges replacement at their preferred schedule.
  • Perforations: Pinhole perforations from corrosion or fatigue, often at the outlet end of the heat exchanger where condensation forms on 80% AFUE units during cold-start cycles. Perforations produce the same CO-in-return-air signature as cracks.
  • Overfire discoloration without structural failure: Blue-to-purple discoloration and surface scale on the heat exchanger walls from chronic rich-burn combustion (the altitude derate was never performed) without visible cracking or perforation. This indicates a furnace that has been stressed beyond design intent but has not yet failed structurally. Our recommendation: manifold pressure correction to achieve proper altitude-derated combustion, and annual heat exchanger inspection at every maintenance visit thereafter.
  • Clean inspection: No visible cracks, perforations, or concerning discoloration. A clean borescope inspection on a furnace with normal combustion analysis readings is a passed heat exchanger. We document this finding in writing — if a competitor has told the homeowner the heat exchanger is cracked and our borescope shows otherwise, the written documentation protects the homeowner from the replacement quote.

Common Furnace Failures in the South Salt Lake Valley

Condensate Drain Blockage (90%+ AFUE Units)

The single most common cause of furnace “failure” calls we receive from October through February on condensing furnaces. The 90%+ AFUE Category IV condensing furnace extracts so much heat from the flue gas that the exhaust condenses into liquid water in the secondary heat exchanger, which drains through a condensate trap and drain line to a floor drain or condensate pump. In the south Salt Lake Valley, two factors accelerate condensate drain blockage: the 15–25 grains per gallon hard water that precipitates calcium carbonate scale inside the drain tubing and trap orifice over two to three heating seasons, and biological growth (algae or fungal biofilm) that develops in the drain trap’s standing water. A blocked condensate drain backs up into the secondary heat exchanger, trips the condensate overflow switch or the pressure switch (depending on the furnace model), and produces a no-heat lockout. The fix: drain clearing with compressed CO₂ or compressed air and a descaling agent. The cost: $45–$85. The misdiagnosis: pressure switch failure ($145–$220 parts and labor). We check the drain first, every time.

Altitude Derate Skipped — SunCrest and Traverse Ridge

A furnace installed at SunCrest (6,200 ft) or Traverse Ridge (6,400 ft) without manufacturer-specified altitude derating runs rich — too much fuel for the available oxygen. The combustion products include elevated CO, soot, and incomplete combustion byproducts that deposit on the heat exchanger’s secondary surface, the flame sensor, the burner ports, and the condensate drain system. Over 3–7 seasons, the accumulated effects include: flame sensor fouling (frequent loss-of-flame lockouts), burner port restriction from carbon deposits (orange or rolling flame), and premature heat exchanger fatigue from the elevated flame temperatures produced by rich combustion. We have corrected altitude derate on furnaces installed by other contractors in SunCrest and Traverse Ridge as the primary service call — after the manifold pressure adjustment, flame sensor cleaning, and burner port inspection, furnaces that were “failing frequently” run cleanly through an entire heating season.

High Limit Switch Trip from Reduced Airflow

The high limit switch on a gas furnace opens when the supply air temperature exceeds the manufacturer’s set point (typically 150–180°F depending on furnace model). The most common cause in the south Salt Lake Valley is restricted airflow: a MERV 13 filter installed in a furnace cabinet designed for MERV 8 (total external static pressure above 0.8″ WC), a dirty blower wheel on an older direct-drive motor, or a duct damper that was closed during summer and not reopened. High limit trips typically manifest as a furnace that starts, runs for 8–15 minutes, shuts off on high limit, and restarts 20–30 minutes later when the limit resets. The symptom is consistent with several other failure modes; static pressure measurement across the air handler at the diagnostic visit identifies airflow restriction as the cause in under 5 minutes.

Control Board Failures on Specific Models

Certain furnace models in our service area have documented control board failure patterns that we track in our service records:

  • Carrier 58MCA / 58CVA series (2010–2016 production): The IFC (Integrated Furnace Control) board in these models has a higher-than-average capacitor failure rate on the line voltage side, typically manifesting as intermittent ignition failure with no consistent fault code. A capacitor measurement on the IFC board identifies the failed component; the board itself may be serviceable with a capacitor replacement rather than full board replacement.
  • Goodman GMS80 series (2005–2012 production): The pressure switch wiring harness connector at the control board develops a high-resistance connection on some units due to connector corrosion in humid mechanical rooms. Manifests as intermittent pressure switch fault codes. Connector cleaning or replacement restores normal operation without board replacement.
  • Trane XR80 and XR90 (pre-2010): The SureLight ignition control board on these units has a known failure mode involving the flashing LED sequence that misreports the actual fault condition. Accurate diagnosis requires reading the LED code against the correct Trane service manual for the specific board revision level, not the generic fault code list printed on the furnace door.

Second Opinions on Furnace Condemnation Quotes

We have overturned condemnation quotes regularly — furnaces condemned by competitors without documented borescope inspection or combustion analysis that, on our diagnostic visit, had a clean heat exchanger, normal ambient CO levels, and a specific repairable cause of the presenting symptom.

Common patterns:

  • Competitor reports “cracked heat exchanger” based on a flame deflection test (passing a hand or a piece of tissue paper near the heat exchanger in a running furnace and noting flame disturbance) without borescope inspection. Flame deflection tests are not diagnostic — flame disturbance near the heat exchanger can result from blower-induced air currents, duct leak induced pressure differentials, or a cracked heat exchanger. Only borescope visual inspection differentiates these.
  • Competitor reports elevated CO “in the home” without specifying whether the measurement was in the return air (meaningful) or in the ambient room air near a natural gas appliance (potentially explained by many sources). A CO reading at the return air grille that traces to the furnace’s flue gas circuit is a heat exchanger concern. A CO reading in the kitchen three rooms away is not furnace-specific evidence.
  • Competitor reports a furnace is “at end of useful life” at 14–15 years without performing any measurement. A 15-year-old furnace that passes combustion analysis, passes borescope inspection, and has normal static pressure and temperature rise is not at end of useful life — it is a mid-age furnace with potentially 5–8 years of remaining service if maintained annually.

If you have received a condemnation quote and want a second opinion, our $89 diagnostic fee applies. The documentation we produce — combustion analysis printout, borescope photo record, static pressure measurements — is yours regardless of whether you proceed with any repair or replacement through us.

Frequently Asked Questions

How much does furnace repair cost in Draper?
Repair cost depends on what actually failed. Common repair cost ranges in our service area: condensate drain cleaning $45–$85; flame sensor cleaning $65–$95 (included in our maintenance visit); pressure switch replacement $145–$220; hot surface igniter replacement $125–$195; inducer motor replacement $285–$475; gas valve replacement $325–$525; control board replacement $395–$750 depending on brand and model; blower motor replacement $375–$625. The $89 diagnostic fee is applied to the repair total if you proceed on the same visit. At any repair cost above $1,000 on a furnace over 15 years old, we present a replacement estimate in parallel so you have both numbers.
My furnace keeps shutting off after a few minutes — what’s wrong?
Three most common causes in our service area, in rough order of frequency: (1) High limit trip from restricted airflow — check your air filter first. A severely restricted MERV 13 filter causes the heat exchanger to overheat, tripping the high limit switch. The furnace restarts 20–30 minutes later when the limit resets, then trips again. Filter replacement may resolve it immediately. (2) Condensate drain blockage on a 90%+ AFUE condensing furnace — the condensate overflows, trips the pressure switch, and causes a lockout. Intermittent restarting follows as the overflow switch resets. (3) Flame sensor fouling — a contaminated flame sensor fails to detect the burner flame after ignition, causing the control board to shut down the gas valve on a false no-flame signal after 5–7 seconds of operation. In a SunCrest or Traverse Ridge home where altitude derate was never performed, flame sensor fouling from carbon deposits is accelerated and typically recurs seasonally.
Is a cracked heat exchanger always a reason to replace the furnace?
A confirmed cracked heat exchanger (visible under borescope, accompanied by measurable CO in the return air) is a safety concern that warrants prompt action — but not necessarily immediate furnace replacement if that is not financially feasible. Options include: temporary operation with daily CO detector monitoring while planning the replacement, heat exchanger replacement if parts are available for the specific furnace model (available on some Carrier, Trane, and Lennox models for 10–15 years after production), or expedited furnace replacement. What is not an option is operating a confirmed cracked heat exchanger without CO detection in the living space — CO in the return air stream reaches occupants directly, and the consequences of CO poisoning in a tightly sealed winter home are serious. We document the finding, explain the options, and do not pressure a specific decision timeline beyond the CO safety discussion.
Can a furnace be repaired if it’s over 20 years old?
Yes — if parts are available and the heat exchanger passes inspection. A 22-year-old American Standard Freedom 90 with a clean heat exchanger, normal combustion analysis, and a failed inducer motor is a $350–$475 repair that extends the furnace’s service life. A 22-year-old furnace with a cracked heat exchanger, a marginal blower motor, and a control board showing age-related component degradation is a different picture. We evaluate each furnace on its measured condition, not its age alone. The honest answer is often: this particular repair is worth doing, but budget for replacement within 2–3 years because the other components are approaching end of life.
Do you make emergency furnace repairs on nights and weekends?
Yes. Our 24/7 emergency dispatch line is staffed by our own team, not a third-party answering service. Emergency criteria for same-night dispatch: indoor temperature below 55°F, suspected gas leak, or active CO alarm. After-hours rates apply to emergency calls; standard rates apply to non-emergency calls scheduled during business hours. SunCrest and Traverse Ridge emergency calls during winter weather events may have extended response times due to road conditions — we communicate realistic ETAs when conditions require it and have never left a SunCrest home without heat in a dangerous cold event.

Contact Draper Heating & Air Conditioning

For furnace no-heat emergencies, second opinions on condemnation quotes, or standard diagnostic visits across Draper, Sandy, Bluffdale, Riverton, South Jordan, and Herriman, our licensed technicians are dispatched from Business Park Drive 24/7.

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