HVAC FAQs & Terminology


How often should I get a tune-up on my HVAC appliances?

We recommend getting your furnace tuned-up once a year. If your furnace is brand new and was just installed, we recommend that you get your first tune-up after two years. This increases the lifespan of your furnace and ensures that it will operate safely and more efficiently. Our furnace tune-up services start at $79.

We recommend getting your water heater tuned-up once a year. This increases the lifespan of your water heater and ensures that it will operate safely and more efficiently. Our water heater tune-up services start at $99.

We recommend getting your boiler tuned-up once every three years. This increases the lifespan of your boiler and ensures that it will operate safely and more efficiently. Our boiler tune-up services start at $400.

We recommend getting your air conditioner tuned-up once a year. If your air conditioner is brand new and was just installed, we recommend that you get your first tune-up after two years. This increases the lifespan of your air conditioner and ensures that it will operate safely and more efficiently. Our air conditioner tune-up services start at $79.

Why should I invest in an energy efficient HVAC appliance?

In general, an energy efficient appliance costs more money up-front. But there are many incentives that make it easier to choose an energy efficient appliance over a conventional one. Because high-efficiency appliances need less energy to operate, they cost you less money on your utility bill. Using less energy also means you reduce your carbon footprint, which benefits our environment. In addition, energy efficient appliances may be eligible for rebates and other financial incentives. This helps reduce your up-front costs. Click here to learn more about available rebates and incentives.

How often should I change my furnace filter?

You should change your furnace filter once every three months during the heating season. Make sure you do the same if you have central air during the cooling season.

My furnace or boiler isn’t turning on. What should I do?

There is a switch located near your furnace or boiler called an SSU switch. It may have accidently been turned off or left in the off position during a repair. Flip the switch to the on position and try again. If this still doesn’t fix your problem, call us at 720-236-1350 to set up an appointment.

The LED light on my thermostat is flashing. What does this mean?

This often happens when the batteries that power your thermostat have run out of power. Change the batteries and this should fix the problem. Otherwise, call us at 720-236-1350 to set up an appointment.

My swamp cooler is leaking water. What does this mean?

This usually means the float valve isn’t closing. This isn’t a complicated issue, but we recommend you give us a call at 720-236-1350 to help you resolve it.

My air conditioner has stopped working. What does this mean?

After several 100 degree days, it is common for the capacitor to go out. Give us a call at 720-236-1350 to make an appointment.

There is a rotten egg smell in my house. What does this mean?

This could mean there is a gas leak in your home. We recommend that you assess this immediately. Open up your home and don’t turn on any appliances or light fixtures. Call your utility company or an experienced technician for a repair. Leave your home immediately as an extra safety precaution. Give us a call at 720-236-1350 or Xcel at 1-800-895-2999.

What level of carbon monoxide is considered dangerous?

Anything over 35 parts-per-million (ppm) is dangerous. At this point your carbon monoxide detectors will go off. If this is the case, you and your family should leave the home immediately. We recommend you call your utility company. Xcel’s phone number is 1-800-895-2999. You may also call us at 720-236-1350 to make an appointment.

What are high-efficiency furnaces?

Here’s something to think about as you start looking to upgrade your furnace: Beginning in 2013, only 90%+ efficient units will be manufactured. Finding an 80%+ unit will be difficult.

Furnaces with 90%+ efficiency have two heat exchangers instead of one. They also condense water vapor that exhausts gases. This means less heat is lost and more is put to use to condition your home. Instead of having a conventional metal vent pipe, 90%+ units use PVC pipe that runs out the side of your house or through your roof. Depending on city codes and height requirements, you may need a flush mount or “gooseneck” kit installed. Concentric kits are required on your roof in “straight-shot” situations. With a 90%+ furnace replacement, you may notice cooler air coming out of your vents during initial start up. This is only because your unit is using less fuel and saving you money! Call us for more information about 90%+ efficient furnaces.

What does AFUE mean?

All furnaces made in this country must have an “Annual Fuel-Utilization Efficiency” (AFUE) of at least 78 percent. This means that a minimum of 78 percent of the fuel is put to use in the process of heating your home. The rest escapes through the flue. The latest and most efficient gas furnaces have an AFUE as high as 97 percent. By contrast, gas furnaces made in the early 1970s typically have an AFUE of only 65 percent. Replacing these old furnaces can make a significant reduction in your gas bill. Keep in mind that the AFUE rating does not factor in heat lost through ducts or pipes. The Department of Energy says can account for as much as 35 percent of total heating energy. Proper insulation and duct sealing is recommended for all furnace types.

Why invest in a 90%+ efficient furnace?

Although a high-efficiency furnace will cost more up-front, it costs less to operate each year and will lower your gas bill.

Annual Estimated Savings for Every $100 of Fuel Cost by Increasing Your Heating Equipment Efficiency
Existing System AFUE

New/Upgraded System AFUE




































































































Source: Energysavers.gov

Suppose you are replacing an old system with an AFUE of 60 percent. A 90 percent efficient furnace replacement will save you $33.33 for every $100 spent on gas. Gas consumption, climate, insulation, and local utility rates determine how quickly your savings will meet up-front cost. In Colorado, a high-efficiency furnace pays for itself. (Veterans Green Jobs can help you calculate the expected annual operating costs of different furnaces.)

In addition, high efficiency furnaces may be eligible for rebates. Click here to learn more about available rebates and incentives!

Cutting your home’s energy use also benefits the environment. According to National Geographic’s environmental website, replacing an old heating system that is 56 percent efficient with a new system that is 90 percent efficient will save 1.5 tons of carbon dioxide emissions each year if the house is heated with gas, or 2.5 tons if it’s heated with oil.

What is the advantage of swamp cooling over air conditioning?

Compared to air conditioning, swamp coolers use water and are more environmentally friendly. Swamp coolers use less energy than central air conditioning, but create more humidity in the home. Windows need to be open to prevent moisture and indoor air quality issues. Several types of swamp coolers are available with varying prices.

Should I stick to storage water heating or should I go tankless?

Tankless water heaters are the highest energy efficient units, but can be very costly up front. Because they are more efficient, you pay less in operating costs over the life of the unit. This not only helps lower your energy bill, but also reduces your carbon footprint. Tankless water heaters may also qualify for rebates. Click here to learn more about available rebates and incentives that help reduce your upfront costs.

Storage water heaters last a shorter period of time, but are less costly up front. You could potentially replace two to three of these units for the price you would pay for a tankless unit.

We suggest you do some research before you buy your next water heater to see what makes sense for your household. Questions you may want to ask yourself: How long are we planning to live in the home? How much do I want to spend? How many people live my home? How much water do they use on a daily basis? Call us and we can help you decide on which type of water heater is right for you.

What does the SEER rating on air conditioning units mean?

SEER stands for “Seasonal Energy Efficiency Ratio”. The higher the SEER rating, the more energy you save. If you have a 10 SEER system and upgrade to a 14 SEER system, you will save about 30 percent on your operating costs.

How is the annual cost of electric energy for an air conditioner calculated?

Here is a brief explanation of SEER ratings and energy consumption in your house – and how these translate to costs:

Electric power is measured in kilowatts (kW). Electric energy is measured in kilowatt hours (kWh). For example, if an electric load that draws 1.5 kW of electric power is operated for 8 hours, it uses 12 kWh of electric energy. In the United States, a residential electric customer is charged based on the amount of electric energy he or she uses. A customer’s utility bill will state the amount of electric energy in kWh for the past month and the cost of the electric energy per kWh.

Air conditioner sizes are often given as “tons” of cooling. One ton of cooling equals 12,000 BTU/h (3.5 kW). One ton of cooling equals the amount of power that needs to be applied continuously over a 24 hour period to melt 1 ton of ice. Use the following formula to calculate your annual operating costs:

Unit size, BTU/h × hours per year, h × energy cost, $/kWh ÷ SEER, BTU/Wh ÷ 1000 kW/W

Example 1:

What is the annual cost of electric energy consumed by a 72,000 BTU/h (21 kW) (6 ton) air conditioning unit that operates for 1,000 hours per year, with a SEER rating of 10, and an electric energy cost of $0.12 per kWh?

(72,000 BTU/h) × (1000 h) × ($0.12/kWh) ÷ (10 BTU/Wh) ÷ (1000 kW/W) = $864

Example 2:

A residence near Chicago has an air conditioner with a cooling capacity of 4 tons and a SEER rating of 10. The unit is operated 120 days each year for 8 hours per day. The electric energy cost is $0.10 per kWh. What is the annual cost of the electric energy required to operate the air conditioner?

First, we must convert tons of cooling to BTU/h.

(4 tons) × (12,000 BTU/h/ton) = 48,000 Btu/h

The annual cost of the electric energy is:

(48,000 Btu/h) × (960 h/year) × ($0.10/kWh) ÷ (10 BTU/Wh) ÷ (1000 kW/W) = $461




AFUE – Acronym for Annual Fuel Utilization Efficiency, which is a thermal efficiency measure of combustion appliances such as furnaces, boilers, and water heaters.

Ambient Temperature – The temperature of the air that surrounds operating equipment.

BTU – Acronym for “British Thermal Unit”, which is the standard of measurement used to measure the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

BTUH – Acronym for the amount of BTU’s in one hour.

Central Air Conditioner System – System in which air is conditioned at a central location and carried to and from rooms in a home by a system of ducts and fans.

Compressor – A pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again.

Condenser – The device in an air conditioner or heat pump in which the refrigerant condenses from a gas to a liquid when it is depressurized or cooled.

Condenser Coil – The device in the outside unit of an air conditioner or heat pump where refrigerant is circulated and releases heat when a fan blows outside air over the coils.

Cooling Capacity – The quantity of heat that a cooling appliance is capable of removing from a room in one hour.

EER – Acronym for Energy Efficiency Ratio, which means the ratio of the cooling capacity of the air conditioner in British Thermal Units per hour to the total electrical input in watts.

Evaporator – Absorbs heat from the surrounding air or liquid and moves it outside the refrigerated area by means of a refrigerant. It is also known as a cooling coil, blower coil, chilling unit or indoor coil.

Evaporator Coil – A series of tubes filled with refrigerant located inside the home that takes heat and moisture out of indoor air as liquid refrigerant evaporates.

Ductless System – A unit with no ducts that only conditions one room.

HVAC – Acronym for Heating, Ventilation, and Air Conditioning.

Heat Pump – An air conditioner capable of heating by refrigeration.

Heating Capacity – The quantity of heat necessary to raise the temperature of a material by one degree.

Insulation – Material(s) that slows the transfer of heat.

Kilowatt (kW) – Unit of electrical power equal to 1,000 watts.

Kilowatt-hour (kWh) – Unit of electrical power equal to 1,000 watts in one hour.

Latent Heat – The quantity of heat absorbed or released by a substance undergoing a change of state, such as ice changing to water or water to steam.

SEER- Acronym for Seasonal Energy Efficiency Ratio, which is a rating that determines the efficiency of air conditioning equipment.

Sensible Heat – Heat energy which is added or removed from a gas, liquid, or solid that causes a rise or fall in its temperature.

Single Package – A combination central air conditioner unit with both a condenser and air handler.

Split System – A central air conditioner consisting of two or more major components, usually containing a compressor unit and condenser as well as an air handling unit.

Ton – A unit of measurement for air conditioning system capacity where one ton of air conditioning removes 12,000 BTU’s of heat energy per hour from a home.