Spencer Heating and Air Conditioning Action Center

Helpful Tips About Researching and Purchasing Your HVAC Services and Products.

Gas Furnace

In a gas furnace heat is supplied by burning gas.  Burner flames heat up the heat exchanger.  The heat exchanger has alternating chambers which separate the flame exhaust from the air you breathe. The blower moves air across the heat exchanger, through the duct system and into your living space.  The by-products of combustion pass harmlessly through the venting system to the outdoors.

Heat Exchanger Cracks  

The heat exchanger can develop cracks or holes and the potential exists for dangerous fumes to mix with indoor air.  According to:

  • The American Gas Association (AGA) publication 'Fact Sheet On Heat Exchangers' "Any visible crack or hole discovered is reason for requiring replacement of the heat exchanger or furnace."
  • The Society of Professional Real Estate Inspectors manual 'Heating Systems Inspection' states: "...the committee consulted with all of the major furnace manufacturers, as well as the American Gas Association (AGA), and The Gas Research Institute (GRI).  The consensus of opinion is that THERE IS NO ACCEPTABLE CRACK, OPENING OR DAMAGE IN A FURNACE HEAT EXCHANGER" (capitalization theirs).  When you attempt to sell your home a home inspector will likely see the crack and require a furnace replacement.
  • The Atlanta Gas Light Company's policy is to "Red Tag" and refuse to light the pilot on any furnace with any visible crack or hole.


Gas furnaces are rated by AFUE (Annual Fuel Utilization Efficiency).  The AFUE indicates how much of the furnace's heat goes into the house vs. how much heat goes up the exhaust flue.  Prior to 1992 most furnaces were rated at about 60% AFUE.  Today the minimum efficiency rating is 80%.  A high efficiency furnace is 90% and above.  The added cost of a 90% furnace is about $1,300 - $1,500.

Single-stage vs. two-stage 

A single-stage furnace works on "high stage" all the time.  You get the full blast of heat when less might be better.  The furnace might short cycle because it satisfies the thermostat faster.  A two-stage furnace operates on low fire unless high fire is called for by the thermostat.  This will give you longer heating cycles and more even heating temperatures.


The variable speed blower motor adjusts airflow for greater comfort.  This motor uses about half the electricity of a traditional motor.  It also increases the efficiency of the air conditioner by about 7% and offers better humidity control.  Where blower noise is a factor this blower offers the quietest operation.

Electric Heat-Pump

A heat-pump is basically an air conditioner that cools and heats.  By manipulating refrigerant pressures it transfers heat from indoors to outdoors in the summer, then reverses refrigerant flow and transfers heat from outdoors to indoors in the winter.  Heat-pumps will often have electric heat strips that come on when the thermostat is set for emergency heat.  The heat strips will also come on to aid the heat-pump if the weather is so cold it falls behind.  The heat-pump efficiency is rated according to its air conditioning mode.

Electric/Gas Dual-Fuel

A dual-fuel system utilizes both a heat-pump and a gas furnace.  The heat-pump works at its greatest efficiency when the temperature outside is mild.  When the outside temperature gets cold enough the thermostat turns off the heat-pump and turns on the gas furnace. The dual-fuel system also turns the heat-pump off and the gas furnace on when the "emergency heat" function at the thermostat is utilized.

Click here to schedule the repair or maintenance of your furnace

An air conditioner cools and dehumidifies indoor air by transferring heat from inside a structure to the outdoors.  All central air conditioners employ three pieces of equipment.  The indoor coil is located downstream from the blower and removes heat from the air stream.  The outside condenser expels the heat.  The blower circulates conditioned air through the duct system.


Air conditioners are rated by SEER (Seasonal Energy Efficiency Ration).  For every one SEER increase, electricity usage is reduced roughly 10%.  As a ratio, this percentage decreases as the SEER rating rises above 10 SEER.  Houses built prior to 1992 would normally have a/c's with ratings of 7-8 SEER.  In 1992 the EPA set the minimum allowed at 10 SEER.  In January 2006 that minimum was raised to 13 SEER (making most of today's equipment appear "obsolete").  Today's standard efficiency 13 SEER a/c units use about 23% less electricity than a 10 SEER unit (produced in 1992 - 2005), and about 46% less than a 7 SEER unit (units produced prior to 1992).

Did you know...It is common for manufacturers to take the highest rating number possible for an air conditioner and then use that number in the unit's name(for example, having 15 in the model number does not mean what you are buying will get 15 SEER).  This practice is misleading and is capitalized on by a/c companies.  An air conditioner can be assigned an efficiency rating only after it is determined which indoor coil it will be matched with.  We always let you know what you will be getting. Ask your a/c company to tell you what the engineering specs say, or call us and we'll be glad to look it up.

Click here to schedule the repair or maintenance of your air conditioner

Heating and cooling systems are usually trouble-free and easy to maintain. Efficient operation is a function of good regular maintenance. No matter what type of system you have, there are several things you can do to help keep it in top condition.

The air fliter - located in or next to the furnace - should be replaced regularly. To check the filter, take it out and hold it up to the light. If you see more than a dusting, replace it with a new filter of the same type and size, regardless of the length of time it has been used.  The size of the filter is printed on the edge of the frame. The arrow should point to the furnace which is the direction of the air flow.

Bushes, ivy and other debris around the outside air conditioning should be cut back.  Greenery can greatly reduce capacity and efficiency inhibiting the free flow of air into the unit.   Also, objects within three feet above the unit can cause the hot air that has just been expelled from the unit to recycle back into it.  This condition can greatly reduce efficiency and capacity, as well as hurt the compressor.  Sometimes this state of affairs cannot be avoided, as in the case of a deck built over the unit.  When it comes time to replace the unit this condition can be remedied.

Q  My system does not heat or cool well.  What might be my problem? 

A  Check your air filter, make sure your registers are open, move furniture blocking return and supply air openings, make sure the air conditioner outside is free from bushes, vines and other debris.  Make sure you have sufficient attic insulation.  If you get a lot of afternoon sun coming through your windows try having your windows treated with UV film, planting a tree or installing an awning to block the sun.  Have a service company check the system.

Q  My air conditioner or heater does not come on at all.  The fan does not even move air.  What might be my problem

A  Check the breaker box and turn the breaker marked "Furnace" off then on.  If the breaker is tripped this will reset it.  If you have recently changed your filter make sure the switch next to the furnace which turns it off has not been turned off.  If you needed to open the blower door to change the filter make sure the door has been put back properly.

Q  I have a tri-level house with one heating and cooling system.  The temperature varies on each floor. Is there anything I can do?

A  This is a common problem; heat rises and cold air falls.  Moreover, the thermostat is usually located in the heart of the house, usually on the main floor, which does not experience the temperature extremes of the other floors.  As a result, the thermostat satisfies more quickly shutting the system off.  This state deprives the other floors of much needed conditioned air.  To help remedy this problem try leaving the "fan" function on at the thermostat, close the downstairs registers in the summer to push the cool air up and close the top floor registers in the winter to push heat to the lower floors.  Appropriately sizing heating and cooling equipment when it is time to replace can also reduce temperature disparities.

Q  My house is uncomfortably humid in the summer.  What might be my problem?

A  Make sure your air conditioning has a clean air filter.  You might want to have a service company check the refrigerant charge.  An appropriately sized air conditioner can remove a lot of humidity.  You might look into a central dehumidifier which can remove a large amount of water from the air.

Q  Why is my basement musty and cold in the summer? 

A  This might be due to ground source water.  If this is the case call a water abatement expert to assess your basement.  If your basement shares a system with the main floor you might try leaving the fan in the "on" position at the thermostat to continuously introduce the fresher air from the main floor to the stuffy basement.  A whole house dehumidifier can pull a great deal of moisture out of the air.