In this article, we go over a few guidelines for performing maintenance on your control dampers: from what to look for in an inspection to the best practices for cleaning damper components.
Dampers Need Regular Maintenance
You might be wondering where your control dampers are at this moment. Where are they? Are they all in full working order? When was the last time you observed your control dampers in action? You have a maintenance schedule for each unit, right? These are important questions.
You should check all HVAC equipment periodically and ensure that each part is fully operational. Control dampers are no exception.
You should inspect your dampers on a semi-annual basis: at least once every six months. Life safety dampers will have additional requirements for inspection, as dictated by UL standards.
Certain dampers may require a more frequent maintenance schedule depending on each damper's application. Timing between inspections will depend on several factors, such as the damper's location and the type of air flowing through. For instance, dampers subjected to dusty air will need to be checked more often. Manufacturers will provide general guidelines for maintaining the damper, along with suggested timetables for maintenance.
Always follow the literature provided by the manufacturer, including any guides on inspection and maintenance.
Damper Maintenance - Inspecting, Cleaning, and Lubricating
A full inspection will examine all parts of the damper: blade surfaces, blade axles, the linkage, the damper’s actuator, and any pins and bushings.
Blade action will be the first thing to inspect. Locate the damper in the duct. Cycle the damper’s actuator from open to close several times, to make sure that every blade moves freely. Look for moments when the blades turn slowly or don’t move at all. Disconnect the actuator from the damper and test the blade rotation with your hand. This will rule out the actuator if binding or seizing occurs.
Look for dust or grit that might hinder movement. Ensure that every part moves smoothly.
For actuators, inspect the housing and the driving arm for signs of wear or damage. If any components are damaged, you will need to replace the actuator with a working one before sending it in for repairs. Power on electric actuators and make sure they properly rotate the blades. Test pneumatic actuators through your integrated air pressure system, to make sure the system provides adequate pressure to operate the actuator. Replace any faulty or damaged actuators before returning the damper to service. Check for signs of rust or wear on pins and bushings on the damper, then replace them as needed.
Check the seals along the edges of the blades and in the damper’s jambs. Blades should close tight and flush. Silicone seals may deteriorate over time, so be sure to replace them if they look worn. Replacement seals are self-adhering. Tear the old seal off of the blade, wipe away the old adhesive from the blade edge, and then apply the new seal.
With the inspection complete, take some time to clean and lubricate any moving parts. Use a lint-free cloth when cleaning parts to avoid leaving behind any debris. The damper’s manufacturer will specify which lubricants are best for their damper.
As a rule, do not use oil-based lubricants. Oils will attract dust and grit to any lubricated parts. This will hinder blade movement and ultimately defeat the purpose of the lubricant. Consult the manufacturer’s maintenance guide for approved lubricants. Non-metallic parts, such as molded nylon bearings, will not require lubrication.
Summary - A Checklist For Maintaining Control Dampers
There is a lot to consider when maintaining your control dampers. Here's a quick checklist to work with:
- Inspect damper blades for free, unhindered movement.
- Test dampers with the actuator unplugged, to ensure the damper works on its own.
- Check seals for tight closure and replace worn seals with new ones.
- Replace any worn or rusted bushings and pins.
- Clean the damper with a lint-free cloth.
- Oil all moving metallic parts with approved lubricants. (No oil-based!)
Always consult the manufacturer’s literature on proper maintenance before starting your maintenance routine. Keep your HVAC system in peak condition by cleaning and maintaining your control dampers. A healthy damper makes for a healthy HVAC system.
MCDLG & Continuing Education
Want to know more? MCDLG offers a free self-paced course on control dampers.
"An Introduction to Air Control Dampers" covers the basics of control dampers: what they do, where they go in an HVAC system, the principles that dictate their performance, and guidelines for installing and maintaining your control dampers.
This course provides continuing education credits for a variety of institutions, including ASHRAE's PDUs. Learn the basics of control dampers and earn credit, at your own pace. Visit the MCDLG Campus Portal today!