4 FM quick reads on HVAC
1. Condensate Line Maintenance for Good IAQ
Striving for good IAQ in your facility means keeping an eye on a million little things, such as condensate drain lines. Condensate drain lines should be adequately trapped to overcome fan pressures and should be piped to drains on both rooftop and interior HVAC equipment.
If the static pressure of the fan on the air handling unit is greater than the depth of the trap and the condensate drain is on the negatively pressurized side of the air handling unit, air is pulled back through the drain trap. As the air enters the interior of the unit, it's like a little geyser of water from the drain line. Water from the drain line and the condensate pan could hit the interior insulation in the unit, and once that happens it becomes a likely site for microbial growth.
Condensate drain lines should not only be adequately trapped, but should be piped away from HVAC equipment to roof or floor drains. Condensate water that is not piped to drains can accumulate in low spots on the roof or in mechanical rooms. This water again becomes a breeding ground for microbes and could infiltrate the HVAC system through a rooftop outdoor air intake or a mechanical room that is acting as a mixing plenum for return and outdoor air.
2. Monitoring Is an Essential Part of Water Treatment Program
Effective water treatment is a complex process involving steps designed to address system-specific problems such as scale, corrosion and fouling. Each category of problem requires its own specialized treatment. That may be the use of biocides to control microbiological fouling, the addition of chemicals to limit the build up of scale, and the use of different chemicals to reduce corrosion.
But it's not enough to implement those measures. Rather, it is essential to monitor the water within the system to ensure that problems are not developing. For example, many biocides are corrosive. If too high a level of biocide is used, it may cause corrosion; if the level is too low, however, the biocide may not be effective at controlling microbiological growth. What's more, make up water conditions can change from season to season, or if a new source of make up water is used.
To ensure that the water treatment program is effective, weekly monitoring is generally advisable. For example, dip slides can be used to keep track of bacteria levels. Although testing involves labor and possibly some equipment costs, that cost is a small price to pay in comparison to the problems it can prevent.
3. Replacing HVAC Equipment? Take a Fresh Look at Options
Today's topic is replacing HVAC equipment.
It's easy to think that the best replacement for a piece of HVAC equipment is an updated version of the same piece of equipment. If the old equipment basically did the job, a new unit will do even better. It will be more reliable and more energy efficient and will likely offer more control options. What's more, you already know that it will meet the needs of the space it is serving.
But replacing in-kind — that is, buying essentially the same piece of equipment — may not be the best route. For one thing, the needs of the space may have changed. If the cooling load has increased, more capacity may be needed. Or perhaps there is now a critical load that justifies redundancy in the cooling system.
It's also possible that changes in technology may offer new options that are worth considering. Or perhaps a different configuration of equipment — two smaller chillers instead of one larger unit, for example — might match the load better.
Replacing a unit in-kind may be easier, faster and less expensive in the short term, but it can be a mistake in the long run.
4. Ceiling Panel Durability an Important Consideration
Ceiling tiles need to stand up to some forms of use and abuse. If a facility executive cuts corners on ceiling durability for cost reasons, the ceiling panels may need to be replaced much sooner than anticipated, costing more money in the long run.
Schools and other seasonal-use facilities are spaces where special durability considerations are important, for example. When school isn’t in session, HVAC systems are usually turned off to save money. This is often the most humid part of the year, however. When HVAC systems are turned back on in the fall, the ceiling panels can bow. For spaces like these, ceiling panels designed to tolerate a high level of humidity and temperature fluctuation are important.
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