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Cambridge S-Series Preventative Maintenance Schedule

Proper maintenance is essential to keep your Cambridge S-Series heating unit running efficiently and prevent costly repairs. This blog outlines a preventative maintenance schedule for your unit. Depending on whether your unit has filter sections, inspections should be done two or four times a year. In this guide, we will cover crucial tasks like checking air filters, greasing bearings, inspecting belts, and more. By following these steps, you'll extend the lifespan of your equipment and optimize its performance, reducing energy costs and minimizing downtime.

Let's get started on maintaining your Cambridge S-Series unit.

Why Preventative Maintenance Is Important for S-Series Units

Regular preventative maintenance helps keep a Cambridge S-Series heating unit operating efficiently and reliably throughout the heating season. Routine inspections can identify worn components, dirty filters, loose connections, airflow restrictions, and other issues before they develop into more significant equipment problems.

A consistent Cambridge S-Series maintenance schedule can also help facility teams:

Maintain proper airflow and discharge temperatures
Support efficient heater operation
Identify worn belts, bearings, and other mechanical components
Keep burners and combustion components operating properly
Reduce unexpected equipment downtime
Extend the service life of the heating unit
Identify maintenance issues before they become more costly repairs

For facilities that depend on S-Series units for heating large commercial or industrial spaces, documenting maintenance activities can also make it easier to track equipment condition over time.

Suggested inspection Frequency:

The recommended inspection frequency depends on whether the S-Series unit has filter sections:

2 times per year for units without filter sections
4 times per year for units with filter sections

Maintenance frequency may also need to account for the operating environment. Facilities with high levels of dust, dirt, or other airborne contaminants may require more frequent inspection or cleaning of certain components.

Always refer to the applicable Cambridge S-Series technical manual for complete maintenance procedures and requirements for your specific unit.

S-Series Maintenance Checklist

S-Series Air Filter Maintenance: Clean or replace the air filters if necessary because dirty filters will reduce CFM and could damage the discharge air sensor.

Service the filters as needed based on the “loading” experienced. Clean filters typically start out with a pressure drop across the filters between 0.15 and 0.25” WC. Cleaning or replacement is generally required below the pressure drop increased by a factor of 4 times the initial clean value.

S-Series Blower Bearing Lubrication: Grease the blower bearings. The grease should be evenly distributed around the race.

Heaters with 3 HP or smaller motors have permanently lubricated, double-shielded and double-sealed ball bearings which do not require additional lubrication. Heaters with 5 HP or larger motors require lubrication on intervals of 3 to 6 months. Use Duralube AW-2G, Goldplex (Lithplex HC 150 SMG), Shell Gadus S2V100 2 or Mobilith AW2 grease. Grease should be bearing quality and compatible to lithium bases thickener.

S-Series Motor Bearing Lubrication: Grease the motor bearings. Do NOT use the standard bearing grease in the Baldor motor. This motor takes special grease.

Motors are pre-greased normally with Exxon Polyrex EM. Equivalent greases which are compatible with the Exxon Mobil lithium complex greases and electric motor polyurea greases per ASTM D6185. Follow the below schedule for your motor grease intervals.

Turn the disconnect switch off when performing service or maintenance functions.

Check the belt tension and inspect for wear: If the belt is too tight, it can prematurely wear out the bearings and the belt. If the belt is too loose it can slip or squeal. Periodic belt adjustments may be required.

Using a Browning Belt Tension Checker and straight edge, verify proper belt tension according to the following table:

Series Blower Wheel Inspection: Examine for accumulation of dust on the blades. These surfaces must be kept clean.

Cycle the unit on and off in all modes of operation: This ensures components are working per specifications. Check DC voltage on modulating valve to ensure unit is not stuck in High or Low fire modes.

S-Series Burner Maintenance: The burner is for the most part self-cleaning, but if the application is extremely dirty or dusty it may become necessary to periodically clean. For steps on how to clean the burner, reference our tech manual, page 82.

S-Series Flame Sensor Maintenance: Inspect the flame sensor. Remove and re-install to ensure corrosion doesn’t form within threads. A steady reading between 2.0 and 6.0 µA should be verified. If reading is low, clean with Emory Cloth and plan to return in the near future to replace.

S-Series Hot Surface Ignitor Inspection: Inspect hot surface ignitor and replace if degradation is apparent.

Check the discharge temperature: Use a wired thermistor at the mixing box and calibrate the system if necessary.

S-Series Control Panel Inspection: Inspect the control panels. Look for any loose or frayed wired connections and make sure all connections are tight.

S-Series Gas Valve Inspection: Perform a gas valve leak test. This verifies the integrity of the valves. All relief vents on the gas controls should also be checked for blockage. In general, if the voltage to the coil is correct, sluggish valve operation, excessive noise, or leakage will indicate that cleaning is required.

Verify that the manifold differential gas pressure matches the nameplate: It is extremely important that this is set up properly. If the manifold pressure is incorrect, the heater temp rises, and its efficiency will be affected.

Check the calibration of digital thermostats: Press the up arrow and hold it; the display should show 0F. If not, the calibration may have been adjusted to show a warmer or cooler temperature than desired.

Our application-focused engineering team & your local rep collaborate closely for facility fit and system design. Our customer service group can deploy for training, troubleshooting or startups – whatever it takes for your project to be a success. If you ever need to get in touch with a Cambridge expert, don't hesitate to reach out!

You can also schedule an hour call with our tech support! Find a time that works best for you and our team will you help you on your next project.

S-Series Maintenance FAQs

1. How often should a Cambridge S-Series unit be serviced?

Cambridge S-Series units should generally be inspected twice per year for units without filter sections and four times per year for units with filter sections. Units operating in particularly dusty or dirty environments may require more frequent attention.

2. What is included in a Cambridge S-Series preventative maintenance schedule?

A typical S-Series preventative maintenance inspection includes checking air filters, blower and motor bearings, belt tension and wear, the blower wheel, burner, flame sensor, hot surface ignitor, gas valves, manifold gas pressure, discharge temperature, electrical connections, thermostats, and overall unit operation.

3. How often should S-Series air filters be changed?

S-Series filters should be serviced based on the amount of loading experienced by the unit. Clean filters typically have an initial pressure drop of approximately 0.15 to 0.25 in. WC. Cleaning or replacement is generally required when the pressure drop increases to approximately four times the initial clean value.

4. What should I check on a Cambridge S-Series unit before heating season?

Before heating season, inspect the filters, blower wheel, belts, bearings, burner, flame sensor, ignitor, gas controls, electrical connections, discharge temperature, thermostat calibration, and overall unit operation. Any issues identified should be addressed before the unit is placed into regular heating service.

5. What should I do if my Cambridge S-Series unit is not heating properly?

Start with the applicable maintenance and operational checks, including filters, airflow, burner and ignition components, gas controls, discharge temperature, and thermostat operation. If the issue persists, contact Cambridge Air Solutions or your local Cambridge representative for troubleshooting assistance.