Common questions about a furnace, heat pump or air conditioner.
Q: What is a BTU and "ton of A/C"?
A: BTU, or British Thermal Unit, is a measure of heat energy. It represents how much heat energy an air conditioner unit can remove from the surroundings. Air conditioner manufacturers needed a way to measure the amount of cooling energy (heat removal) that is produced for a specific period. These measurement units are BTU’s and ton(s) of refrigeration.
A BTU is defined as the amount (quantity) of heat needed to raise the temperature of 1 pound of water by 1 degree F. For example: when 5 lb of water is heated from 30°F to 40°F, then 50 BTU of heat energy is added to the water, or you could say the water now contains 50 BTU of heat energy. The BTU calculation is:
BTU = weight in lbs. times change in temperature in °F
BTU = 5 lb x (40°-30°) = 5 x 10 = 50
HVAC technicians use the term BTU to describe the quantity of heat energy contained in a substance. In the example above, the water contains 50 BTU.
Let's review a furnace that has 30,000 BTU. That means the furnace will produce 30,000 BTU of heat energy within a specific period.
When it comes to air conditioning, it is entirely the opposite. A 30,000 BTU air conditioner means that the unit will remove 30,000 BTU of heat energy from the surroundings. Every heating or air conditioner unit’s rating is based on it's ability to remove or add heat energy. This allows consumers to compare units of various manufacturers and select units appropriately sized for their residence.
Ton of refrigeration (or ton of air conditioner)
Air conditioning “tonnage” is a measurement used to size air conditioner or refrigeration units.
The term “ton of refrigeration” goes way back to when ice was used as the source to remove heat. A ton of refrigeration refers to the amount of heat needed to melt 1 ton (2000 lb) of ice in a day (24 hours). It requires 144 BTU of heat energy to melt one pound of ice at 32°F to one pound of water at 32°F. To convert a ton of refrigeration to BTU multiply 2000 lb by 144 BTU/lb, which equals 288,000 BTU.
288,000 BTU is how much heat a one ton A/C unit will remove in 24 hours. In one hour, this unit will remove 12,000 BTU of heat (288,000 BTU/24 = 12,000 BTU) from the residence. A 2.5 ton A/C unit = 30,000 BTU/hr (5000 lb x 144 BTU/lb / 24 hr).
Q: Why should I consider a heat pump instead of an air conditioner?
A: 1. In its heating mode, the output temperature of the air supplied by a heat pump is less than the air supplied by a furnace. The warm air entering a room from the heat pump is about 100oF compared to about 120o to 130oF from a furnace. This means the heat pump warms a room gradually and more evenly than a furnace. It's similar to running your bath water by turning the hot water faucet to the desired warmth setting rather than turning the faucet to maximum hot and then turning if off and waiting for the water to cool down.
2. It is much more efficient in warming your home in mild weather as compared to a gas or propane furnace.
3. A ductless heat pump, or mini-split, may be installed in older homes that lack traditional ductwork, providing a more efficient heating and cooling solution.
Q: What is important in deciding what brand of HVAC unit to get?
A: Although cost is usually the deciding factor, it is often more important to consider the unit's reliability and efficiency. To save $1000 up front, but spend $30 more per month to operate the unit, and $500 or more to repair it in the first few years, is no cost savings (not to mention if the unit fails on a cold winter night)! Consumer Reports ranked Rheem furnace and A/C units highest in reliability. Combined with Evergreen's annual maintenance to ensure peak performance, your initial expense is repaid quickly and you can enjoy month after month of savings and worry-free operation.
Q: What if my furnace doesn't work?
A: Sometimes, a child (or you) may accidentally turn off the power switch located near the unit. It usually looks like a standard light switch. Confirm that this is actually in the "on" position. Also check that the cover is correctly installed on the front of the furnace. There is a safeguard which prevents the unit from operating if this cover is not in place. If these don't solve your problem, check the breakers to see if they tripped. You may need to push it to the "off" position before moving it to "on". If none of these solutions work, call us at 208-623-6331 to schedule a technician.
Q: What should I NOT do when choosing an A/C or heat pump?
A: Although volumes may be written on this topic, we will touch on a few points.
1. See What is important in deciding what brand of HVAC unit to get?
2. Get "hung up" on SEER ratings. Many companies will claim extremely high SEER ratings to convince you to purchase the high-end model. You should keep in mind that SEER ratings are based on a laboratory setting under specific environmental conditions. Simply put, that SEER rating is not guaranteed to be reproduced in your residential installation. And to pay thousands more yet have your return on investment take 20 years, or more, doesn't make sense! Buy a reasonably efficient unit (check your utility company for what SEER rating qualifies for a rebate).
3. Focus on HSPF ratings either, for many of the same reasons. Check your utility for rebates.
4. Choose upfront price over total price (even looking at the first few years of ownership).
Does installation of the indoor unit include an appropriate thermostat and all the required sheet metal components? Often an additional charge.
Does the heat pump or A/C unit installation include a new pad, electrical disconnect and refrigerant charge? Not always. How long is the warranty? What is covered? Is regular maintenance required for the warranty to be in effect? Is any maintenance included in the purchase price?
Read the fine print and ask questions.
Q: How can I improve my indoor air quality?
A: The simplest (and least expensive!) thing to do is regularly change your furnace filter. This enhances air quality and improves air flow. Beyond that, an air filter or UV lamp further cleans the air of fine particles and/or kills mold spores and bacteria. If suffering from dry skin, or you have fine wood furniture or flooring, consider a whole house humidifier.