Fall Coil Tips for Facility Managers

By David Pflum and Jim Leeds

HVAC coils are a mechanical system component that often fall into the "out-of-sight; out-of-mind" category. A few minutes of attention in the approaching Fall season can help prevent issues which could lead to occupant discomfort, energy inefficiency, leaks, or outright failure. It can also put you in a much better position to respond in the event your building quickly needs a replacement coil.

Coil Check-up

Inspect the coil for signs of leakage. Look for fin discoloration or rust. These can indicate internal leaks.

Straighten any bent coil fins to maintain maximum heat transfer. Bent fins reduce the effective coil surface and correspondingly reduce coil capacity.

Always check fin appearance after any handling of the coil and after any servicing is done near the coils.

Fin combs are sized according to number of fins per inch of the coil. They can be purchased at most mechanical supply stores. For relatively small bends that require only minor repair, other tools may be used to evenly space the fins. Be careful not to damage the coils.

Clean Coils are Happy Coils

Keep coils clean to maintain maximum performance. For operation at highest efficiency, clean coils more often during periods of high cooling demand or when dirty conditions prevail. For example, remove the build-up of cottonwood fuzz that is a seasonal issue in some regions.

Prior to cleaning, disconnect and lockout electrical power. Cover motors to prevent moisture from penetrating into the windings, potentially causing motor failure. Remove large debris from the coils and straighten fins before cleaning.

Clean refrigerant coils with cold water and detergent or with one of the commercially-available chemical coil cleaners. Rinse coils thoroughly after cleaning.

Do not clean the coil with hot water or steam. The use of hot water or steam (in non-steam coils) as a refrigerant coil-cleaning agent will cause high pressure inside the coil tubing and subsequent damage to the coil.

Do not use acidic chemical coil cleaners. Do not use alkaline chemical coil cleaners that, after mixing, have a ph value greater than 8.5 without also using an aluminum corrosion inhibitor in the cleaning solution. Failure to follow these guidelines or the manufacturer's instructions for use of cleaning chemicals could result in damage to the unit.

Exercise extreme caution with any caustic or toxic chemical coil-cleaning compounds to prevent personal injury or equipment damage.

Steam Coil Tips

Implement a maintenance program to insure that steam traps are operating correctly and at maximum efficiency. Failure to do so could result in premature failure of the coil and loss of warranty due to condensate backing up into the coil causing leaks, or allowing the coil to freeze during low ambient conditions if supply air drops below 40° F.

Steam distributing coils may be called "NON-FREEZE" coils. However, these coils will freeze if temperatures drop below the freezing point. If there is the possibility that the coils will experience freezing temperatures, install freeze safeties in the system to prevent damage to the coils.

Preventing Coil Freeze-ups

One useful tip to preventing damaging coil freeze-ups is to assure the coils are pitched toward the return connection. This allows condensate to exit and not freeze in the coil, potentially bursting it.

Responding Effectively to Coil Replacement Emergencies

Even with attentive maintenance, a coil can occasionally fail. The good news is a bit of planning can eliminate panic and get the unit back online with minimal downtime. Identify your servicer or coil resource in advance, and have the contact info accessible.

What to Look For in a Replacement Coil Provider

Proper fit and timely delivery are the key criteria to a successful coil replacement. If you work with a service contractor, seek one who has demonstrated responsiveness and attention to detail. A number of replacement coil manufacturers provide online software selection programs. Look for ease of use. Flexibility in quick ship options can help you meet your time frame demands as cost effectively as possible. Seek a supplier whose processes leak-test every coil under water with dry nitrogen, meeting the UL Burst Test. The coil provider should include a one year warranty.

Conclusion

With a little extra thought and attention to coils this Fall, these simple advance preparations can:

• Maintain occupant productivity and comfort
• Sustain energy efficiency
• Establish predictable maintenance
• Enable effective emergency coil replacement

David Pflum is Vice President and General Manager of Precision Coils, LLC. He has 16 years of experience in leadership positions at several HVAC firms. Jim Leeds is Sales Manager for Precision Coils with 24 years experience in the coil industry. Precision Coils; Right Fit. Right Now™; is a business of Unison Comfort Technologies.