FIRST PUBLISHED ON ENERFICIENCY.COM BLOG OCTOBER 2001 – BUT STILL RELEVANT
Fuelish Furnace Fitness
Give Your Home’s Heater a Workout
BY ENERFICIENCY DOUGLAS BLACK
Your furnace might be wasting a lot of energy – and a lot of your money! Improperly functioning furnaces also contribute to pollution – inside and outside. Here are steps you can take to make sure old man winter won’t outrun your home – or run-out your pocketbook!
Safety first.This guide does not cover all applicable code and safety procedures, so make sure you follow manufacturers’ instructions in the use and care of your furnace. Have qualified contractors handle repairs and installation.
If you smell gas:
- call your gas company immediately
- do not turn electrical switches on – or off
- open doors and windows
- do not use open flames
If a pilot light has gone out
- shut off the gas supply to the unit
- wait for accumulated gas to escape
- relight following instructions on your furnace
- strike the match first, hold it at the relighting point, and turn on the gas
How a furnace functions.
A furnace has three basic parts; the Combustion System, the Control System, and theDistribution System.
The Combustion System Fuel is burned in the combustion chamber. The heat which is produced first travels through a metal box called a heat exchanger. The heat exchanger transfers heat to the air moving through the distribution system. Hot gases are then vented out of the furnace through the flue pipe and chimney.
The Control System Two thermostats control heat distribution to your home. Smart operation of these thermostats can offer big savings without reducing comfort. Programmable “set-back” and “step-up” thermostats will operate automatically to save energy, much like cruise control on an automobile.
Heating season settings should be 68 degrees from 7:00 pm through 11:00 am, and set-back 5 degrees (to 63 degrees) from 11:00 am through 7:00 pm. Cooling season settings should be 73 degrees from 7:00 pm through 11:00 am, 78 degrees from 11:00 am through 7:00 pm. You should also manually turn the thermostat down whenever you are away from home for extended periods. You can save about 10 percent for every 10 degrees you set your thermostat back for 8 hours or more.
A second thermostat located within your furnace compartment, regulates the operation of your blower. Because moving air feels cooler, furnace technicians will often set the blower to turn on at 135 degrees (F) and off at 100 degrees. You can achieve significant savings by adjusting the pointers on the dial (not the high limit pointer) to turn the blower on at 100 degrees and off at 80 degrees. You’ll get more heat out of your heat exchanger.
The Distribution System Warm air is delivered through a series of metal ducts called warm air supply ducts. A fan, often called a blower, draws air back to the furnace through cool air return ducts.
Furnace fitness requires that air is not hindered anywhere along its pathway. This means unblocking all registers, maintaining the blower and fan belt, and changing filters regularly.Furnace fix-ups.
A furnace needs a regular tune-up to keep it running efficiently. The $40-$60 you spend will pay for itself quickly and help to identify safety problems.
If you have a natural gas furnace have it tuned every 2 years. If you have oil tune it every year. If you suspect a problem, have it checked.
When you get a tune-up, ask the service person to check;
- Efficiency rating – the efficiency rating is obtained by comparing the exhaust gas temperature and the level of carbon monoxide (CO2)
- Electrical Wiring – wiring should meet all local, state and national codes
- The Burner – the burner should be cleaned. Air intake levels should be adjusted to ensure proper combustion
- Thermostat – the thermostat needs to be accurate. Make sure it is mounted level and plumb.
- Heat Anticipator – the heat anticipator is a miniature heater which warms the thermostat and shuts the burner off before the house reaches the desired temperature. The blower keeps running for several minutes, continuing to heat up the house.
- Blower and Filter – the blower should be cleaned and oiled. The filter, or filters, should be cleaned or replaced. A typical fiberglass filter costs a dollar or two – buy a dozen and replace it the first of every month. The blower thermostat should also be set to deliver the most energy (turning the blower on sooner and off later)
- Chimney – check the chimney for corrosion, air flow (draft), and obstructions
- Leaks – check for leaks in the gas lines leading to your furnace. A leaking heat exchanger may indicate a safety problem and a need for furnace replacement.
- Ductwork – check for leaking ducts in your basement. A certified Home Energy Rater can perform a pressure test to identify leaky ductwork, and other air leaks in the envelope of your home. Just by identifying and sealing leaky ductwork, a typical homeowner can often save enough money over a couple of seasons to pay for the test – after that the savings are gravy!
Furnace Fitness Checklist
____ THERMOSTATS (ROOM and BLOWER)
____ BLOWER and FILTER
____ LEAKS (DUCTWORK, GAS LINE, and HEAT EXCHANGER)
Getting the Heat. Most of the heat you pay for never gets to you! Here are a few ways to get the heat where you want it. Your home will also stay cooler in the summer.
Insulate Your Home. Proper insulation in the walls, attic, windows, and basement of your home will reduce energy loss. Insulation is measured in terms of R-Value (the resistance to heat flow). In the Midwest, for instance, the attic space should have an R-Value of 19, the exterior walls R-15, and the basement walls should be R-10 or more.
Reduce Air Leaks. Air leakage can account for 25 percent of the heat loss in your home. Surprisingly, loose-fitting windows and doors may account for only a small portion of this loss. Attics, basements, walls, and ducts should all be closely inspected for heat “bypasses”. Small cracks are big losers! A certified Home Energy Rater can perform a pressure test to identify air leaks in the envelope of your home so you can put your efforts where they will return savings.
Seal cracks and penetrations around
- plumbing, gas, and electrical lines
- attic doors, chimneys, and vents
- tops of wall cavities in the attic
- wall switches and outlets
- window trim, frames, jambs, and sashes
- cracks in walls, bricks, and ceilings
- where any building materials meet
Use proper materials and methods. Many sealants are available. Read the label!
Deal with Ducts. Leaking uninsulated ducts can be responsible for much of the heat loss in your home. Warm air supply ducts which are located in the unheated and unoccupied areas of your home (usually basements or attics) are the first priority.
Ducts can be sealed with a high grade silicone caulk, duct tape, or foil tape and then insulated with special duct wrap insulation. A professional grade ductwork sealant, while more expensive, will prevent leaks from recurring for far longer. These materials are available from many heating equipment suppliers.
If you see a white, chalky material (like the cast you had on your broken arm as a kid), it is probably asbestos. DO NOT TRY TO REMOVE IT! Disturbing asbestos releases the fibers into the air, creating the potential for lung cancer. A trained professional hazardous materials mitigation team should look at the problem if substantial material is present. For small amounts, CAREFULLY cover the material with plastic before insulating.
Dampers are sometimes installed in ducts near the furnace. These, or individual room registers, can be adjusted for better heat distribution and air flow.
Furnace Selection. A new higher efficiency furnace can offer major energy savings, improve comfort, reduce the greenhouse gas emissions that contribute to global warming, and add value to your home. Dollar savings can help pay for the new unit. When replacing, consider these helpful tips:
- Furnace Condition – if your furnace is over 15 years old, in need of major repairs (more than $400), or operating at an efficiency of less than 60 percent, consider replacement. Newer condensing units can operate at over 90 percent efficiency levels.
- Furnace size – if your home has been (or will be) properly insulated and weatherized, you can often get by with a much smaller and often less expensive furnace. A Home Energy Rating will give you an Equipment Sizing Summary, showing the heating and cooling loads for your home “As Is” and also “With Improvements”.
- Efficiency – new furnace efficiencies vary between 65 percent and 97 percent AFUE (Annual Fuel Utilization Efficiency). High efficiency may cost more but can cut fuel bills 30 to 40 percent. Savings due to higher efficiency will help pay for the furnace.
- Contractor Selection – ask for at least two bids and read them carefully. Ask for warranties on the equipment and references, as well as professional affiliations such as the local Home Builders Association or Mechanical Contractors Association.
- Flue Sizing – a properly-sized flue is a safety concern. When replacing a furnace, make sure that the flue pipe is properly sized. This will allow proper draft and reduce corrosive condensation in the flue or chimney.
You Don’t Need Aerobics Classes to practice furnace fitness! A safe and efficient heating system is your key to lower fuel bills, improved comfort, and furnace fitness! By understanding furnace operation, maintenance, and proper weatherization techniques, you can go a long way toward controlling costs in your household.