4 FM quick reads on HVAC
1. Replacing Rooftop Units Before They Fail Can Bring Significant Benefits
Today's tip comes from Building Operating Management: Look at the big picture to persuade top management it's worthwhile to replace rooftop HVAC units before they fail.
If your organization has made a practice of replacing rooftop HVAC units only when they fail, there are several arguments that you can use to try to persuade top management to replace them proactively instead.
The biggest consideration is the impact on business. Rooftop units often fail on the most extreme temperature days. Suppose one fails in the midst of a heat wave. Depending on the building, the indoor environment will be anywhere from unpleasant to unbearable.
How important is that? The extent of the impact will depend on the type of organization. An office building may be able to stay open and put up with grumbling from employees. But in a retail facility, customers can't be told to stay. And even with office space, if it's a leased building, the tenants aren't likely to forget the inconvenience.
Getting a replacement in as quickly as possible will be a top priority, of course. But that may mean having to accept a less than optimal replacement unit because it is the first one available.
When making the case to top management, remember to focus on business issues. Talk to department heads or other business leaders whose functions will be affected by failure of a rooftop unit. Find out if they can provide any estimates of cost to the organization. Talk to contractors about how long it would take them to install a new unit and what impacts a rush order might have on choices, then translate all of that into business terms such as higher first costs, overtime costs, or higher long term energy costs.
3. MSCA Star Certifies Non-Residential Mechanical Service Contractors
Today's tip from Building Operating Management: For facility managers looking to hire HVAC contractors, one certification program to check out is the MSCA Star certification.
The Mechanical Service Contractors of America created the MSCA Star designation in 2003 for mechanical service contractors that serve industrial, commercial and institutional facilities. Among the requirements for the MSCA Star designation:
• Contractors must have been involved in the heating, ventilating, air conditioning and refrigeration industry for at least five years.
• At least 25 percent of the contractor's service techs must hold the UA Star certification, an HVACR service technician certification from the United Association of the Plumbing, Pipefitting and Sprinklerfitting Industry of the United States and Canada.
• Employees have to attend at least one national or local program sponsored by MSCA or its parent group, the Mechanical Contractors Association of America each year.
• Inventory control programs for trucks and tools are required for contractors.
• Contractors must have documented service safety and health programs and must maintain what MSCA calls an "outstanding" safety record.
• All field personnel must be required to wear photo ID cards.
• Contractors must maintain a high-level of customer service. The MSCA Star qualification process checks contractor references with customers. To receive UA Star certification, technicians have to pass an exam designed to ensure that they are qualified to service, repair, maintain or retrofit a wide range of mechanical systems. Technicians also have to complete a 5 year apprentice training program and have work experience.
A third-party personnel certification agency, National ITC Corporation, administers the MSCA Star program, as well as the UA Star program and a wide variety of other industry certifications. NITC is certified under the ISO 9001 quality management standard and is ANSI-accredited.
4. A VFD Offers Energy Savings, Other Benefits from Part-Load HVAC Operation
Today's tip comes from James Piper, contributing editor for Building Operating Management: Variable frequency drives, or VFDs, offer multiple benefits for HVAC systems.
For more than 20 years, VFDs have successfully been installed on fan and pump motors in wide range of variable load applications. The most significant benefit of the use of a VFD is energy savings. By matching system capacity to the actual load throughout the entire year, major savings in system motor energy use is achieved.
Another benefit of the units is reduced wear and tear on the motors. When an induction motor is started, it draws a much higher current than during normal operation. This inrush current can be three to ten times the full-load operating current for the motor, generating both heat and stress in the motor's windings and other components. For motors that start and stop frequently, the heat and other stresses produced contribute to early motor failures.
In contrast, when a motor connected to a VFD is started, the VFD applies a very low frequency and low voltage to the motor. Both are gradually ramped up at a controlled rate to normal operating conditions. With no significant inrush current, heating and stresses are practically eliminated, extending motor life.
VFDs also provide more precise levels of control of applications. For example, high rise buildings use a booster pump system on the domestic water supply to maintain adequate water pressure at all levels within the building. Conventional pump controls in this type of application can maintain the pressure within a certain range, but a VFD based system can maintain more precise control over a wider range of flow rates, while reducing energy requirements and pump wear.
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