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Sterling QVSD-400 - User Manual

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INSTALLATION INSTRUCTIONS AND SERVICE MANUAL
STERLING SEPARATED COMBUSTION
GAS-FIRED INDOOR DUCT FURNACE
(S) SCDFM-4
J30-05374
HVAC PRODUCTS
260 NORTH ELM ST., WESTFIELD, MA 01085
TEL: (413) 564-5540 FAX: (413) 562-5311
www.sterlinghvac.com
MODELS: QVSD-100 thru 400
01/11
FOR YOUR SAFETY
The use and storage of gasoline or other fl ammable vapors and liquids in open containers in
the vicinity of this appliance is hazardous.
FOR YOUR SAFETY
If you smell gas:
1. Open windows.
2. Don’t touch electrical switches.
3. Extinguish any open fl ame.
4. Immediately call your gas supplier.
Model No.
Serial No.
ATTENTION: READ THIS MANUAL AND ALL LABELS ATTACHED TO THE UNIT CAREFULLY BEFORE
ATTEMPTING TO INSTALL, OPERATE OR SERVICE THESE UNITS! CHECK UNIT DATA PLATE FOR TYPE OF GAS
AND ELECTRICAL SPECIFICATIONS AND MAKE CERTAIN THAT THESE AGREE WITH THOSE AT POINT OF
INSTALLATION. RECORD THE UNIT MODEL AND SERIAL No.(s) IN THE SPACE PROVIDED. RETAIN FOR FUTURE
REFERENCE.
APPROVED FOR USE IN CALIFORNIA
INSTALLER'S RESPONSIBILITY
Installer Please Note: This equipment has been test fi red and inspected. It has been shipped
free from defects from our factory. However, during shipment and installation, problems such
as loose wires, leaks or loose fasteners may occur. It is the installer's responsibility to
inspect and correct any problems that may be found.
RECEIVING INSTRUCTIONS
Inspect shipment immediately when
received to determine if any damage
has occurred to the unit during
shipment. After the unit has been
uncrated, check for any visible
damage to the unit. If any damage is
found, the consignee should sign
the bill of lading indicating such
damage and immediately file claim
for damage with the transportation
company.
Install, operate and maintain unit in accordance with manufacturer's
instructions to avoid exposure to fuel substances or substances from incomplete
combustion which can cause death or serious illness. The state of California
has determined that these substances may cause cancer, birth defects, or other
reproductive harm.
Improper installation, adjustment, alteration, service or maintenance can
cause property damage, injury or death. Read the installation, operating and
maintenance instructions thoroughly before installing or servicing this equipment.

Table of Contents

Questions and Answers

  • J
    Jason WilkinsSep 23, 2025
    What does it mean if the hi-limit switch is tripping on my Sterling QVSD-400?
    • S
      Susan KimSep 23, 2025
      If the hi-limit switch is tripping on your Sterling Furnace, it could be due to several reasons. The unit might be overfiring, so adjust the manifold pressure if it's too high or verify and replace burner orifices if required. Air flow may be too low, so increase air flow and check the fan size and voltage. Finally, the switch itself may be defective, requiring replacement.
  • N
    natalieshepardAug 23, 2025
    What to do if my Sterling Furnace pilot will not light or stay lit?
    • H
      Hector GardnerAug 23, 2025
      If the pilot light on your Sterling Furnace won't light or stay lit, start by ensuring all manual gas valves are open and the pilot adjustment screw on the combination main gas valve is not set too low. Purge any air from the gas line and follow the lighting instructions on the label near the gas valve. Clean the pilot orifice with compressed air or solvent, being careful not to ream it. Check for extremely high or low gas pressure. Eliminate any drafts around the unit. Inspect and correct any faulty wiring to the pilot valve or ignition system. If none of these steps work, the gas valve may be defective and need replacement.
  • A
    Amanda JohnsonAug 25, 2025
    Why is my Sterling QVSD-400 Furnace power ventor motor not running?
    • K
      Kristopher HallAug 25, 2025
      If the power ventor motor on your Sterling Furnace isn't running, first check and tighten all wiring connections according to the diagrams. Ensure the thermostat wires tagged “W” and “G” are connected, unless special thermostats are in use. If the wiring is correct, the motor overload protector or the motor itself may be defective, requiring replacement. Also, check the power ventor relay by ensuring 24V is present across terminals 1 and 3 on the fan relay. If it is, jumper terminals 2 and 4; if the motor then runs, the relay is defective and needs replacement. If 24V is not present, check the wiring diagrams.
  • J
    Jessica DavisAug 27, 2025
    What to do if my Sterling Furnace burner won't turn off?
    • D
      David BrownAug 27, 2025
      If the burner in your Sterling Furnace won't turn off, consider these steps: Relocate the thermostat away from drafts. If that doesn't work, replace the thermostat. Check the wiring diagrams to ensure proper thermostat or transformer wiring at the gas valve. Inspect for short circuits, such as staples piercing the thermostat wiring, and correct them. If these steps don't resolve the issue, the gas valve might be defective or sticking and needs replacement. Also, check for excessive gas supply pressure.
  • C
    Chelsea JohnsonAug 27, 2025
    Why is my Sterling Furnace making a noisy flame?
    • H
      herbert72Aug 28, 2025
      A noisy flame in your Sterling Furnace can be due to several reasons. First, there might be too much primary air, in which case you should close the air shutter. It could also be a noisy pilot, requiring a reduction in pilot gas. An irregular orifice causing a whistle or resonance would necessitate replacing the orifice. Lastly, excessive gas input could be the culprit, requiring you to reset the manifold pressure. If resetting the manifold pressure doesn't solve the issue, consider replacing the regulator section of the combination gas valve or the complete valve, or check with your local gas supplier for the correct orifice size and replace it if necessary.
  • K
    Kenneth Aguilar MDSep 18, 2025
    What to do if the pilot lights but the main valve does not energize on my Sterling QVSD-400 Furnace?
    • D
      danielle87Sep 18, 2025
      If the pilot light on your Sterling Furnace ignites, but the main valve does not energize, begin by checking for loose S8600 connections, ensuring the term MV feeds the main valve. Inspect for a cracked or broken sensor ceramic, and if found, replace the pilot assembly. Check the sensor/spark lead for continuity, replacing it if needed. Measure 24 volts from term MV to term MV/PV. If 24 volts is present, replace the main valve; if not, replace the S8600 Igniter.
  • L
    Laura GilmoreSep 15, 2025
    What does it mean if there is no spark in my Sterling Furnace?
    • H
      Heather JonesSep 15, 2025
      If there is no spark in your Sterling Furnace, first ensure the thermostat is calling for heat by closing the thermostat contacts. Check for 24V across the 24V terminals of the S8600. The spark gap might be closed or too wide, so set the gap to 0.1". Lastly, a broken or cracked ceramic on the spark electrode could be the issue, requiring replacement of the pilot assembly.
  • K
    Kelly BurgessSep 17, 2025
    What to do if there is a spark but the pilot does not light on my Sterling Furnace?
    • B
      Betty GentrySep 17, 2025
      If there is a spark but the pilot does not light on your Sterling Furnace, check for loose S8600 connections, ensuring the term PV feeds 24V to the pilot valve. Verify proper gas pressure, as pressure that is either too high or too low may cause a problem. Confirm the spark is in the pilot gas stream and that it arcs from the electrode. Also, check the pilot line for kinks and ensure there are no drafts.
  • S
    Sara ClarkSep 6, 2025
    Why is my Sterling QVSD-400 power ventor motor turning on and off?
    • B
      brendacarsonSep 6, 2025
      If the power ventor motor on your Sterling Furnace turns on and off while the burners are operating, it could be due to several reasons. First, ensure the ventor relay heater terminals are connected per the diagrams. A defective ventor relay switch could also be the problem, requiring replacement of the ventor motor. Additionally, the motor protector might be cycling on and off, so check the motor amps against the motor nameplate rating and check the voltage, replacing the power ventor motor if defective. Finally, ensure the motor is properly oiled.
  • T
    Tabitha PierceSep 3, 2025
    What to do if my Sterling QVSD-400 is not producing enough heat?
    • J
      James TaylorSep 3, 2025
      If your Sterling Furnace isn't producing enough heat, consider the following: The gas input might be incorrect. The heater might be undersized, especially if the heated space has been enlarged. In this case, have a heat loss calculation performed and compare it to the heater's output (80% of input). Your gas supplier or installer can provide this information, and if the heater is undersized, consider adding additional heaters. A malfunctioning thermostat could also be the issue, requiring replacement. Also, check for proper air movement through the heat exchanger and check the voltage to the fan motor. Clean the power ventor motor and adjust dampers accordingly.

Summary

Installers Responsibility

Inspection and Correction of Issues

Installer is responsible for inspecting and correcting any problems that may occur during shipment or installation.

Receiving Instructions

Shipping Damage Inspection and Claims

Instructions to inspect the unit for shipping damage and file claims with the transportation company.

General Safety Information

Safety Terminology Definitions

Explains hazard alert symbols and terms used in the manual for safety.

Unit Specifications

Physical Dimensions and Gas Inlet

Provides key physical dimensions, gas inlet sizes, and weight for different unit models.

Performance Data

Airflow and Temperature Rise Metrics

Lists input/output ratings, airflow capacities, and temperature rise for various unit sizes.

Installation Clearances

Minimum Clearance Requirements

Details minimum safe distances from combustible materials and for service access.

Special Installation Locations

Outlines installation requirements for aircraft hangars and public garages.

Installation Procedures

Ductwork and Airflow Design

Covers recommended ductwork designs and airflow adjustment for optimal unit performance.

Suspension and Mounting

Provides guidance on proper suspension points and ensuring secure mounting of the unit.

Electrical Connections

Power Supply and Wiring Standards

Details power supply requirements, adherence to electrical codes, and grounding procedures.

Thermostat Installation and Settings

Instructions for thermostat mounting, wiring, and setting the heat anticipator for optimal control.

Wiring Diagrams

Honeywell Ignition System Diagram

Illustrates the wiring for units utilizing the Honeywell ignition system.

Johnson Ignition System Diagram

Illustrates the wiring for units utilizing the Johnson ignition system.

Combustion Air Piping

Combustion Air Piping Installation Requirements

Details installation requirements for combustion air piping, including codes, pipe materials, and length limits.

Exhaust Venting

Exhaust Venting Installation Requirements

Covers installation requirements for exhaust venting, including codes, pipe materials, and termination guidelines.

Gas Piping

Pipe Sizing and Selection

Provides formulas and tables to calculate and select the appropriate gas pipe size based on input and length.

Pipe Installation

Gas Supply and Pressure Requirements

Details standards for installing gas piping, including pressure testing and required gas pressures.

Burner Components

Burner Drawer Parts Identification

Identifies common parts found in the burner drawer assembly.

Gas Input Rate

Input Rate Calculation

Explains the process for calculating the gas input rate using gas meter readings and BTU content.

Pressure Adjustments

Pilot and Manifold Pressure Settings

Provides procedures for adjusting pilot and manifold gas pressures for optimal operation.

Unit Operation

Initial Lighting Procedure

Step-by-step instructions for safely lighting the unit for the first time.

Primary Air Shutter Adjustment

Describes how to adjust the primary air shutter for proper burner flame characteristics.

Maintenance Procedures

Periodic Service Routine

Outlines a routine inspection and service schedule for maintaining the unit.

Power Venter Assembly

Component Identification and Notes

Identifies components and provides notes on assembly and flue size requirements.

Troubleshooting Guide

Flame and Gas Odor Issues

Addresses troubleshooting steps for flame appearance issues and gas odor detection.

Ignition and Condensation Problems

Provides solutions for ignition problems and condensation of water vapor.

Cycling and Ventor Operation Issues

Troubleshoots issues related to rapid burner cycling, noisy power ventor, and pilot ignition problems.

Ventor and Heat Output Issues

Troubleshoots issues related to power ventor operation and insufficient or excessive heat output.

Spark, Pilot, and Safety Switch Issues

Resolves problems with spark, pilot operation, and hi-limit switch tripping.

Replacement Parts and Warranty

Ordering Parts and Warranty Terms

Details how to order replacement parts and the terms of the product's limited warranty.

Sterling QVSD-400 Specifications

General IconGeneral
BrandSterling
ModelQVSD-400
CategoryFurnace
LanguageEnglish

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