Furnace

Home heating of one sort of another has been around for millions of years but it’s been less than one hundred years that furnaces, as we know them, made their appearance. Although the history of furnaces is far shorter than the history of home heating, there have been significant improvements in the short years of its existence.

The earliest heating systems used campfires and fireplace hearths that radiated heat outward. It wasn’t until after the early 1800s that the first version of the forced-air furnace came about. It took the invention of electricity, fans and ductwork to make them work for whole-house heating.

The more common kind of heating in the early years was radiant heat emanating from fireplaces, hearths and later on, wood stoves. Over the years, the furnace has replaced radiant heating, especially in areas like ours where winters are mild and the heating load is light. Compared to radiant systems, they’re easy to install and heat homes quickly.

Important Improvements

While the history of furnaces reveals that improvements came slowly, since the 20^th century, plenty of changes have made furnaces more efficient and effective. The most recent upgrades include:

• Variable-speed technology. A variable-speed air handler is an upgrade well-suited for this climate. When the heating load is moderate, the furnace runs at a lower speed, which saves energy and increases your comfort. It will run on low for longer periods, which gives all rooms in your home a chance to thoroughly warm, instead of those closest to the air handler.
• Condensing technology. These furnaces use two heat exchangers to extract nearly all the heat that the fuel creates. A standard furnace has just one heat exchanger and wastes as much as 20 percent of the fuel it uses. The most efficient condensing furnaces waste from one to two percent.

Modern gas furnaces have safety features that shut the furnace off when there’s a problem with carbon monoxide, a deadly byproduct of the combustion process. If you aren’t sure what safety features your furnace has, you can schedule furnace maintenance with your HVAC company and ask. Here are more furnace safety tips.

Operating Your Gas Furnace Safely

1. Your main safety concern with your gas furnace is carbon monoxide. Although a properly functioning gas furnace will produce small amounts of CO that are not generally harmful, it’s important to monitor CO production so that you will know if it ever reaches the danger zone. CO monitors are your best defense against this hazard. Check CO monitors regularly to make sure batteries are working or that wires are connected, and that sensors are operational. Monitors five years old or older should be replaced. Mount monitors outside each bedroom.
2. When your HVAC tech checks your furnace, ask about the heat exchanger. Over time, small cracks can develop in this part of the furnace, from which CO may leak out. Also ask about the burners. The flame should burn blue rather than orange. Burners may need to be cleaned periodically.
3. Change your air filter as recommended. Clean filters promote good airflow that helps your system heat more efficiently. It also keeps dust from circulating in your home.
4. Keep obstructions away from vents, registers and the furnace itself.
5. Always be sure the front panel door of the faurnace is in place. Without the door, you can increase the risk of CO poisoning. Generally, furnaces won’t operate without the door in place; however, if you have an older furnace, it may not have this safety feature.
6. Keep anything combustible, including solvents, paint and gasoline, well away from the furnace.
7. Keep your registers open.

Is optimum furnace efficiency possible in your home? Your furnace comes from the manufacturer with an official efficiency rating called AFUE (Annual Fuel Utilization Efficiency). This figure expresses the percentage of energy consumed that actually contributes to usable heat versus the amount lost in the combustion process.

Today, standard efficiency furnaces have AFUE ratings around 80%. More expensive high-efficiency furnaces with secondary heat exchangers deliver efficiency as high as 95% AFUE.

Here are some reasons why your furnace may not be living up to current furnace efficiency standards:

It’s too old.

Gas-fired furnaces last 15 to 20 years so a unit still on the job today may have been manufactured to meet AFUE standards that were lower than present minimums. If you don’t know the age of your furnace, write down the make, model and serial number. Contact the manufacturer to get an age estimate. If it’s more than 15 years old, upgrading to a new furnace built to today’s higher standards may be the best way to improve efficiency.

Neglected maintenance.

Every furnace should receive annual maintenance by a qualified HVAC service technician. This includes a list of manufacturer-approved procedures that support optimum efficiency as well as maximum performance , safe operation and lower heating costs. Most manufacturer’s warranties also require this to maintain coverage. If professional preventive maintenance has been neglected, schedule a furnace tune-up now to improve efficiency.

Improper sizing.

Every new furnace installation should include a professional heating load calculation. This determines the ideal BTU capacity to meet the unique heating requirements of the home. Over-sized furnaces cycle on and off too rapidly and degrade efficiency while under-sized units don’t heat the house uniformly and run overly-long cycles.

Household issues.

Heating-related issues outside the furnace itself can have a major effect on furnace efficiency. For example, deteriorating ductwork that leaks conditioned air can cause the furnace to run extended cycles to maintain thermostat settings, reducing efficiency and raising operating costs. Insufficient insulation, especially in the attic, can also impact furnace energy consumption.

Like all machines, aging furnaces can begin to regularly malfunction. This could be highly problematic in the middle of a cold night. Fortunately, you can troubleshoot many common forced-air furnace problems. Once you know what the problem is, you can determine if you need to have a qualified professional make a house call. Often, the fix is simple and can be done immediately yourself.

When troubleshooting an aging furnace, first check the thermostat. Make sure it is set to the “heat” position and that the desired temperature setting is higher—or warmer—than the current temperature. Next, check the furnace power supply. Sometimes an ordinary light switch is installed near a furnace for a quick power shut off. Also check the breaker box and make sure the furnace switch is in the “on” position. Once you’ve made sure the furnace is getting power, set the thermostat to the “off” position and wait 10 minutes.

After waiting 10 minutes, return the thermostat to the heat setting, look into the furnace and see if the igniter glows red. The igniter burns hot and is easily seen when functioning. You may have to remove the furnace access panel to see the igniter’s bright glow, but some furnaces are equipped with portholes for this purpose. If the igniter is functioning, the next thing to check is the gas flow. It’s easy to accidentally turn the handle on a gas valve and shut off the flow.

If the furnace ignites, produces warm air but prematurely shuts off, there could be several reasons that will depend on your particular furnace type. Also, if the gas flow is on and the igniter appears to function but does not fire up the furnace, it could be a control board problem.

It will soon be time to turn on the heat in your San Diego area home, and before you do, be sure to schedule your annual furnace tune-up to reap these far-reaching benefits:

• Greater system efficiency.
• Lower utility costs associated with heating your home.
• Extended operating life for your system
• Fewer breakdowns during the winter.
• Safe operation of your system.
• Lower carbon footprint due to fewer emissions.

The tune-up checklist varies among different companies, but a reputable and qualified contractor will ensure that these key tasks are performed to ensure the efficiency and safety of your furnace:

• Test for dangerous carbon monoxide leaks.
• Lubricate moving parts of your system to prevent friction.
• Inspect the ventilation system for obstructions and other damage.
• Check the gas pressure and burner combustion to ensure they meet system specifications.
• Clean and inspect the blower assembly for optimum airflow.
• Inspect the heat exchanger for cracks, corrosion and other damage.
• Test the controls to ensure proper cycling.
• Measure the voltage and current on the motor.
• Inspect your ductwork for loose joints and obstructions that result in air loss.
• Check your thermostat for accuracy.

Several things should be on your fall home maintenance checklist to ensure your furnace continues to operate safely and efficiently:

• Stock up on good-quality, pleated air filters. Check your filter every month, replacing it when it’s caked with debris. A clean filter improves your indoor air quality, protects your system from dust buildup, and ensures proper airflow to your system.
• Test your smoke and carbon monoxide detectors and replace the old batteries with fresh ones. Make sure you have one of each type of detector on every floor in your home, with one near your bedrooms.
• Know the location of your gas shutoff valve and keep it accessible in case of an emergency.