Gas Furnace Types

This Gas Fired Unit Heater Serves a Large Open Area

Gas furnaces come in a variety of sizes and can be used for different applications. By and large, the most common gas furnaces use natural gas and utilize electronic ignition. Electronic ignition gas furnaces are slowly replacing the older style standing pilot furnaces where a pilot light remained lit all the time. Now, with the newer modern electronic ignition, gas furnaces only use gas when there is an actual call for heat. This adds efficiency because with the older standing pilot gas furnace the pilot remained on even in the summer months. While the heat produced by a standing pilot light is negligible, it is still added heat to the system in the summer when the whole purpose in the summer is to remove the heat from the system rather than add heat like a standing pilot would do.

A gas furnace is rated for efficiency by AFUE or Annual Fuel Utilization Efficiency rating. Furnaces installed before the nineties have efficiency ratings down to 60 percent efficient (or less in some cases). The AFUE ratings of gas furnaces is simply the amount of heat delivered by the gas furnace divided by the fuel used to make that heat. Another way to look at AFUE is to measure the amount of heat lost up the exhaust stack. If the furnace delivers 90 percent of the heat produced into the dwelling then ten percent of the heat produced is lost up the stack. Even the highest AFUE rated furnace is going to lose heat up the stack. It is nearly impossible to get 100 percent AFUE out of any gas or oil furnace simply because all oil and gas delivered to a furnace has a small amount of moisture in it. Gas typically has a moisture content of 4 to 5 percent. Oil depends on the quality of oil purchased, how many additives used in the oil, and the integrity of the oil tank and piping system. The end result of all this moisture and additives in the fuels effects the AFUE of the furnace and is the reason why no gas or oil furnace can achieve more than 96 percent efficiency.

The Three Boiler Efficiency Factors

When boiler efficiency is discussed one can mean three different things. This often times can be very confusing to those who do not truly understand boiler efficiency. Boiler efficiency actually comprises of:

• Combustion Efficiency
• Steady-State Efficiency
• Seasonal Efficiency 

To determine true boiler efficiency we must examine all three efficiency factors mentioned above. One of the factors can be determined to be very efficient but if we fail to look at the other factors we can miss another efficiency factor suffering big loss. It is thereby possible to determine that the boiler is very efficient in one aspect but very inefficient in another aspect. It is necessary to look at all three factors (and then some (mentioned below)) before declaring or determining the boiler to be efficient.

What BAS/DDC Does for Facilities

BAS Systems Enhance Energy Efficiency

HVAC Controls, building automation (BAS), direct digital control (DDC Controls) are at the heart of many energy management systems for energy savings. Many of you may be wondering what Direct Digital Control (DDC Controls) is and what and where it is used. DDC Control Systems are mainly used in commercial HVAC control and energy management system applications in building automation. DDC & building automation itself is an energy management system which saves management companies and building owners hundreds of thousands if not millions of dollars every year by efficiently controlling air DDC/building automation system (BAS) should have trim and respond capabilities. conditioning and heating comfort systems. DDC is where mechanical and electrical systems and equipment are joined with microprocessors that communicate with each other and possibly to a computer. This computer and controllers in the building automation system can be networked to the internet or serve as a stand alone system for the local peer to peer controller network only. Additionally, the controllers themselves do not need a computer to operate efficiently as many of these controllers are designed to operate as stand-alone controllers and control the specific equipment they are assigned to control. With a few exceptions, each DDC or building automation controller holds their own programs and has the ability to communicate to other DDC building automation controllers. It is important for the DDC or building automation controllers to communicate to each other. If the network fails for whatever reason then the system may still function (because the DDC controllers in building automation systems are stand-alone) but it will not function as efficiently as designed. Building Automation & DDC Control Systems grows more and more complex as time passes but it will save in energy and maintenance costs if installed and programmed properly. Energy Management Systems, DDC Controls Systems and Building Automation Systems (can be one in the same) are definitely the way of the future and are replacing older less efficient systems everyday.