Airflow Control, IAQ, and Efficiency Products
It also varies on the type of equipment involved, pointed out Raj Shah, manager for systems development and engineering, Carrier Residential and Light Commercial Systems. And in many ways, the savings and performance can be amplified by the system’s controls.
The fan, he said, does several things; it circulates air between heating-cooling cycles, and enables all air quality features that require air circulation. “It’s especially true in situations like heating,” he said; “if you don’t have continuous fan, you don’t have air quality control.” It does use energy, so applying variable-speed technology is critical.
Some system controls, like Carrier’s new Edge thermostat and the more advanced Infinity system, offer humidity control as well as temperature control. This also is affected by modulating fan speed.
The Edge’s humidistat “actually works best in conjunction with variable-speed air movers,” said Shah, to remove more moisture from the air. “The indoor air mover in our system is the most critical element,” he said. “It optimizes heating and cooling efficiency for single- and multi-stage heating and cooling. It’s best achieved if the air handler moves the right amount of air, optimizing air movement.”
VARIABLE FLOW“Managing the indoor air is critical for all of these reasons,” Shah said. “With too much or too little air, you can also get into trouble. Everything revolves around the indoor air handler. The controlling element, in matching the right airflow to the mode of operation, is very critical. The Edge is basically a thermostat device, and it does control airflow to manage humidity. Multiple stages of heating and cooling are also controlled. It enables the air handler to know what to do, what to run at what speed.”
“In today’s HVAC industry, the importance of energy consumption has never been more apparent,” said Jay Bauman, sales and marketing manager, fan and ventilator products, Greenheck.
“With energy costs continuing to rise, there should be attention paid to both application and design in order to select the proper air movement equipment. This is especially true when it comes to fan selection. With so many options available, considerations should be given to both construction and performance.”
Fan selection can be critical, he continued. In the past, “a fan was selected for a particular application with the intent that it would run continuously. With the cost reduction and improvements in speed controls, there are significant opportunities to reduce exhaust rates with either variable-frequency drives (VFDs) or electronically commutated motors (ECMs). Airflow rates can be reduced manually or integrated for optimum efficiency with a building automation system. With these options, a reduction in energy consumption can be achieved.”
One more element is zone control, Shah said. “The home’s duct system has a challenge; it can be restrictive and it distributes to various parts of the home.” The Edge works with the company’s zone controls.
Components of the Infinity system “all communicate in a digital way,” Shah said. “In the air-moving scenario, when the Infinity talks to the furnace, it can provide variable airflow to match what the system needs. For humidity control, it can be used where you want to make sure the system does what the system needs for the Infinity control.”
In the heat pump heating mode, the Infinity manages the indoor airflow by lowering airflow to make the space feel warmer and less drafty. “Those systems are very, very comfortable,” said Shah. “It runs for long periods of time, keeping the temperature very even. The air handler is a continuum of speed; you’re matching the airflow to the instantaneous need.”
The Edge can also be used with Carrier’s Hybrid Heat dual-fuel heat pump. “It’s a wonderful energy story,” said Shah. “We feel very strongly that this is gaining in popularity and will continue to do so,” so having a control option in addition to the Infinity line is important.
He added, “The Edge is definitely an attempt to make it easier on the homeowner and the contractor. Basically, it’s the intuitiveness of the system that makes it possible. It is a very easy-to-use stat. It has been laid out with considerable care to make it obvious.”
DIRECT VENTILATIONImproving IAQ is still an important function of ventilation systems, even while they are helping to keep energy costs down. More products work as components of the total system, or even as stand-alone devices.
According to the Environmental Protection Agency (EPA), moisture is a leading cause of mold in the home. “By combining the convenience of a ventilation fan with a light and powerful heater that is directionally adjustable, homeowners can remedy chilly or humid bathrooms,” said Patrick Nielsen, marketing manager, ventilation fans, Broan-NuTone.
The new heater/fan/light from Broan® and NuTone® feature a 1,500-W heater and quiet fan operation at 2.0 Sones for 100 cfm. The heater/fan/light provides the user with warmth after a shower, or bath, light, and ventilation, which protects them from allergenic substances produced through mold.
Offered with both incandescent and fluorescent California Title 24-compliant light bulbs, the heater/fan/light is available in four models: Broan 100 HL (incandescent) and 100 HFL (fluorescent); and NuTone 765 HL (incandescent) and 765 HFL (fluorescent).
A new Steril-Zone™ room air purifier uses a three-stage process to clean the air in rooms up to 1,000 square feet. The ozone-free, portable air purifier incorporates Steril-Aire’s patented UVC Emitter™ to clean the air of bacteria, mold, and viruses. The UVC lamp combines with a high-efficiency air filter and long-life carbon filter to remove three categories of indoor air pollutants and irritants: particulates, volatile organic compounds (VOCs), and microorganisms.
Additional features include a 95 percent efficiency (MERV-16) pleated filter that removes particulate contaminants down to 0.3 micron in size, without using ionization or electrostatic charges; and a commercial-grade quiet fan that moves the air at 250 cfm with an air exchange rate of up to five changes per hour in an average room.
The three-stage air-cleaning unit is concealed from view until it is time for replacement, typically after one year, the company said. Changeout is accomplished by taking out the old filter unit and dropping in the new one, replacing all three components (particulate filter, carbon filter, and UVC lamp) at once.
Generally, when selecting a fan, there are several things to take into account, said Greenheck’s Bauman. “Fan size is often a major consideration due to limited space,” he said. “However, when you are selecting a fan, obtain the necessary airflow with as few fans as possible. Larger fans of similar construction typically consume less energy than their smaller counterparts.
“Another consideration when selecting a fan is utilizing it in the proper application. Proper application in system design will contribute to reduced energy consumption,” Bauman said.
For more information, visit www.broan.com, www.carrier.com, www.greenheck.com, www.nutone.com, or www.steril-zone.com.
Publication date: 09/29/2008