State-Of-The-Art Design And Technology Can Meet Both Energy And Comfort Demands

The CFC phaseout has forced facility executives to take a hard look at their HVAC systems. At the same time, current technology offers significant opportunities for energy savings from the heating and cooling system, typically the second-largest energy user in commercial facilities. On top of all that, the definition of comfort has evolved rapidly over the past decade.

At one time, HVAC systems satisfied the comfort issue by simply making sure the work area was warm or cool enough for most occupants. Now, comfort is being refined to include indoor air quality and outside air exchange.

All in all, it's a tall order: The HVAC system is expected to achieve comfortable conditions for the individual and the masses in the office without harming the delicate global atmosphere. A good example is the CFC phaseout.

Facility executives have three choices: contain CFCs in existing chillers, convert existing units to alternative refrigerants or replace existing machines. Installing new high-efficiency equipment can result in significant energy savings.

Modern HVAC equipment offers improved efficiencies, which are being achieved with better motor performance and better temperature splits in the refrigerant tubes. Today's HVAC systems also offer better part-load efficiencies than older models. Multi-stack units and horizontal screws run more efficiently at part-load levels than earlier models. The economizer bundles are better than they used to be, so the systems run more efficiently.

The recent improvements in chiller efficiencies are the result of refinements in many small places. Manufacturers have done it by better designed compressors, by improving heat transfers. Every component has been reengineered.

New materials, notably plastics, offer major potential for increased HVAC advances that end up benefiting building owners and managers. New materials make units more efficient, easier to install and more corrosion resistant. HVAC systems are becoming more component oriented so they can be put in after the building is built.

Resolving IAQ via HVAC

One of the biggest challenges facing facility managers today is how to meet ASHRAE's current standard for outside air exchange. Variable air volume systems and normal applications need to be reexamined to meet ASHRAE fresh air standard.

To maintain energy efficiency and meet the new standard, multi-zone air-handling systems may need some overhauls. The normal unit has two decks -- one for warm air and one for cool. Provided air is mostly being recirculated, the two decks work effectively.

With the larger temperature differences involved with increased outside air, a neutral zone also may be needed. In a triple-deck system, the outside air is brought by the heat exchanger to that neutral point, before entering the air stream. The result is returned efficiency to the HVAC system in its heating and cooling modes.

Another promising solution is the use of dessicants to pre-condition air without mechanical cooling.

For buildings undergoing major retrofits, the building's air should be tested before renovations begin. Establish the levels of existing contaminants, if any, so that you have a point of reference. After renovations, the air quality should be retested. Periodically, additional IAQ tests should be conducted.

What should building owners do when indoor air actually is better than outside air, as often is the case in buildings located adjacent to major airports? Filtration for gaseous contaminants can play a major role in cleaning the building's air. The health care industry already is aware of the importance of air filtration in controlling the spread of airborne pathogens. But other building owners are just beginning to recognize the importance of proper filtration systems.

Custom comfort

Many advances have been made in HVAC control technology during the past decade. One of the most recent is the ability to control air flow, temperature and even air quality at individual workstations. Because of metabolism and dress in the office, women often complain that they are too cold, while men are too hot.

Advances in DDCs and control systems give us tools to get better air as well as energy conservation from HVAC systems. Everything now is automatic. We can set certain parameters for temperature and humidity with the outside air economizer.

And we can do so much more with the system to protect the health of the people inside the building. For example, if there is a fire and the smoke-detection system is activated, the HVAC controls can stop the air-handling system and start exhausting smoke from the space while alerting local fire and alarm departments.

Electronics in HVAC systems are becoming more integrated with each other: The air-handling unit knows how much is needed from it, and the chiller knows what each air handler is doing and can adjust itself accordingly.

Further refinements in HVAC system controls are on the near horizon. For example, comfort control that relies on more than the temperature to measure a space's overall comfort currently is being investigated by researchers, consulting engineers, ASHRAE and building controls manufacturers. Sophisticated comfort control sensors are being developed that will take into account not just the dry-bulb temperature of today's thermostats but also the mean radiant temperature, air velocity and humidity level.

Julian Arhire is a Manager with DtiCorp.com - DtiCorp.com carries more than 35,000 HVAC products, including industrial, commercial and residential parts and equipment from Honeywell, Johnson Contols, Robertshaw, Jandy, Grundfos, Armstrong and more.

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Ventless Gas Log Fireplaces For Backyard Design

More and more frequently I have clients who want me to custom build outdoor fireplaces in their backyards. Especially in this economy as homeowners maximize their property investment by taking "staycations" the backyard is becoming an oasis of outdoor enjoyment. Fireplaces have traditionally been thought of as wood burning but more and more homeowners are using gas logs as a beautiful and simple alternative to the wood burning fireplace.

Wood burning fireplaces can become complex even when we are building outside. The atmosphere created around a wood burning fireplace is comforting, calming. The crackling and popping of the wood and the smell that permeates the entire yard adds enjoyment to the functional heater. However, building a custom fireplace can become expensive and complicated. In addition to the firebox and the mantle that we devise as the custom plan, a flue and chimney must be built up through the roof and terminated above the roof line. For many homeowners we have worked with, the expense of cutting through a roof, plus the associated laws and inspections attached to resealing a roof and the expense of building a chimney places the project outside an acceptable budget.

For instance, a homeowner decides to build a marble mantle seven feet wide and four feet high. The budget takes into account the marble tile to finish the design and the firebox, structural materials to build the fireplace and labor. Most people do not look at a chimney and think "Wow, that is a great looking chimney" so we do not always account for the ventilation when we design our perfect outdoor accent. The ventilation cannot be skipped just because there is plenty of ventilation outdoors. The proper flue will "pull" the fumes and smoke up and away from the fireplace. Without the vent gas fumes will flow from the front of the fireplace and the area usually reserved for sitting in front of the fire will be hot and smelly. The homeowner contacts a contractor who explains the chimney, flue and roof termination will double the budget.

I have been in this situation many times and the answer is often gas logs. I have had clients with damage to their chimney flue inside a wall and believe they can put a gas log fireplace kit into their wood-burning fireplace instead of repairing the damaged flue. This is a mistake, and a dangerous mistake. Gas logs use liquid propane or natural gas instead of wood for fuel. When gas burns, oxygen is burned and carbon monoxide is created. If there is damage to the flue, a typical gas log fireplace is not the answer because the fresh air ventilation is still necessary to pull out carbon monoxide.

The answer is ventless gas logs. Vent free gas logs do not have to be vented. When a client wants to design a custom outdoor fireplace but they do not want to build a chimney and cut through their patio roof, a vented gas log kit is the perfect solution because no ventilation is necessary.

Ventless gas logs are designed to be used indoors and have several safety features that make them safe inside your home. Manufacturers of ventless gas logs have a limit to the amount of BTU's burned which limits the size of most unvented gas log burners to 30". The size of a firebox that would comfortably hold a 30" gas burner is 42" to 48" which is still a large fireplace. A standing pilot assembly stays lit and heat is tracked with a thermocouple. If the flames go out for any reason, the thermocouple cools and gas stops at the valve. Oxygen depletion sensors are also attached to the gas valve to ensure the flames do not burn up so much oxygen in the house that unsafe conditions are created.

Outdoors a ventless gas log cannot deplete oxygen or fill your home with gas but a different set of issues ensues. Oxygen Sensors can get pollen and dust in them and wind can confuse the pilot assembly's ability to provide continuous heat to the thermocouple. The design of the fireplace and the placement of the logs should be discussed with a professional to minimize these possibilities. These issues do not risk the safety of your family but if the thermocouple thinks the pilot is out because the wind is directing the flame in another direction, your gas log burner will turn itself off. An experienced installer will manipulate the mounting bracket to work around wind issues and position the Oxygen Depletion Sensors so they do not get clogged with pollen and dust.

The benefit to a ventless gas log fireplace outdoors is convenience and cost. The process of building proper ventilation and a chimney can often double the expense of custom fireplaces indoors or outside. Convenience is the ability to create a perfect flame pattern as easily as turning on a barbeque grill. Many gas log fireplaces have complex valve options that allow variable remote controls that alter flame height, on/off remotes, wall switches and thermostatic controllers that turn the fireplace on and off based on the temperature read at the thermostat. I do not recommend any of these valves in your backyard. A manual safety pilot kit has a standing pilot light that stays on always. As long as the pilot is burning, the fireplace can be controlled with a simple control knob. A couple of decorative ceramic pinecones or wood chunks hide the controls. Remotes, wall switches, thermostatic controls and other valves use batteries. Even a gas log fireplace that is under an overhang will be affected by moisture in the air. Here in Florida where humidity is tremendous, a battery operated valve will corrode within a year in most backyards.

Proper placement and a good design will ensure a beautiful fireplace at an affordable price. Years ago ventless gas logs were only for indoor applications where it was impossible to place a vented fireplace. Innovations in log design and burners that burn so clean that very few fumes are created have made unvented gas logs a much more attractive option. Fire effects that do not use ceramic logs but burn crushed fire glass, ceramic fire shapes, river stones or nothing at all have evolved in to a modern design for contemporary homes that do not want a gas log fireplace to appear to be a wood burning fireplace. These fire effects are gaining popularity both indoors and out in the backyard.

Ethanol fireplaces are also a new interesting application. Ethanol burners are rectangular reservoirs with slits or ports in the top to allow flames to keep the alcohol burning. Many ethanol burners can burn for four to six hours before depleting their load and have a heat shield on top that can be used to turn the flames off. Ethanol is functional, beautiful and simple because it does not need ventilation, does not require gas lines running through the house and creates a strong tall flame pattern.

We build custom fireplaces for many home owners and there are always strengths and weaknesses to every option. In my experience, many clients are pleased with ventless gas log fireplaces outdoors in spite of the limitations involved in placing an indoor product in the backyard. Foregoing a chimney and ventilation system saves a lot of money and a lot of time. Vent free gas logs have become as attractive as wood burning and vented gas log fireplaces and they are safe indoors and out. If you are considering a custom fireplace in your backyard or if you are just considering doing something to make your home resort more fun, the ventless gas log fireplace is affordable, safe, simple and can completely change the space you use outside.

http://www.Grill-Repair.com and our backyard design blog site provide replacement grill parts and grill repair tutorials using articles, images and video. We also publish information about the quality of outdoor patio furniture and gas log fireplaces and fire pits. Hopefully this article has assisted you and helped you further enjoy your own backyard resort. We would love to get feedback from you about this article and suggestions for future articles.

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