Ventilation Services at Northwest Heating and Cooling, Inc.

The majority of home and smaller commercial air conditioning systems circulate a compressed gas refrigerant in a closed “split” system to cool and condition inside air. The refrigerant has to be re-cooled and condensed, and outside air is the medium most often used to accomplish this. The term “split” simply means that components are divided into inside and outside portions as opposed to being located together in a “package” unit. The refrigerants, widely recognized by the trademark “Freon” (which is a registered trademark of the DuPont company for refrigerants), helps cool and dehumidify the inside air. In a “forced air” system, an internal blower circulates the conditioned air through ducts to the rooms where the cooler air is needed. The air ducts generally run either below the ceiling and inside the rooms (conditioned air) or in the attic (unconditioned air). An outside fan pulls air across the external parts of the system to cool and condense the refrigerant.

• Compressor (Outdoors): The electric pump, or heart of the system, that circulates the refrigerant in a closed loop between the condenser and evaporator coils. Compressors come in more than one variety. According to Consumer Reports™ “A reciprocating compressor is more trouble-prone than a scroll-type one, they say. While pricier, scroll-type compressors do tend to be higher in efficiency and quieter than reciprocating compressors. Most manufacturers offer both types of compressor.”
• Condenser Coil (Outdoors): A network of tubes filled with refrigerant that remove heat from the heated gas refrigerant and convert the refrigerant into a liquid form again. The excess heat escapes into the outside air.
• Condenser Fan (Outdoors): Pulls air through the condenser coil for heat dispersal.
• Evaporator Coil (Indoors): A network of tubes filled with refrigerant that remove heat and moisture from the air as the refrigerant evaporates into a gas again.
• Air Handling Unit (Indoors): the blower and related portion of the central air conditioning system that moves air through the air ducts.
• Air Filters (Indoors): Air filter elements trap dust, pollen, and other airborne particles as air moves through the air conditioning system. Air filters contribute to both reliable air conditioner operation and health, so we dedicated a page to them.
• Drainage System & Pan: During the normal condensation process, an air conditioner produces a significant amount of water as a by-product. In a central A/C system, there is a primary system of pipes, often made of PVC, that carry this condensate water to the outside of the building. This piping needs periodic flushing to prevent it from getting stopped up with the algae and similar growth. At a minimum, this maintenance should be done by your service company during your annual system tune-up. Your inside A/C system should have an emergency drain pan in case the primary drain lines stop up. This pan usually comes equipped with an automatic cut-off switch that turns your air conditioning system off when then pan fills up with water. Otherwise, water will run out of the pan onto you ceiling or whatever is located below it. The need to flush the drain lines is a prime example of how a little preventive maintenance can prevent a major repair.
• Air Conditioning w/ Heat Pump: often shortened to “heat pump” is a combination central air conditioning and heating system. In one mode, it functions as an air conditioner. In the reverse mode, it becomes a heater. Due to their unique design and special considerations, we have given heat pumps their own page on this website.

The first use of mechanical air conditioning (as we know it) began in 1902 in a New York print shop. Willis H. Carrier developed that system. Although he was not the first inventor to attempt to control indoor temperature and humidity with machinery, the safety improvements with refrigerants and success of Mr. Carrier’s system played a large part in the launch the modern air conditioning industry. A 1906 patent application by Stuart Cramer, a textile engineer, recorded the term “air conditioning” in a patent application for a humidifying device. Although it was first placed in a large residence in 1914, for the first twenty years or so, air conditioning was used mainly to control humidity and temperature to benefit industrial processes, not for human comfort. Carrier used air conditioners to enhance human comfort commercially in a department store and theaters in 1924. After gaining wider acceptance for the equipment in theaters and restaurants, in 1928 he developed the first air conditioner for private home use. That residential system went by the name “Weathermaker”.

The depression of the 1930s followed by the Second World War slowed the spread of air conditioning in homes. After the war ended, consumer demand picked up along with the baby boom. In 1952, housing developments began promoting the benefits of “central air conditioning”. Today, in all except the most temperate summer areas of the U.S., air conditioning is a standard feature in homes and businesses. Today’s air conditioning systems are more efficient and cost more upfront. Today’s central air conditioning systems are much more efficient than their predecessors. The industry uses a rating called SEER for central systems, which is an acronym for Seasonal Energy Efficiency Ratio. Essentially, a higher SEER rating means the air conditioner uses energy more efficiently. When other factors such as thermostat settings are kept equal, a higher SEER results in lower monthly utility bills for the owner or occupant. A central air conditioning unit rated at 16 SEER uses almost a third less electricity than a 13 SEER system. Some outside A/C units are rated at a range, such as 18/19 SEER, depending on what type of indoor equipment they are paired with. For example, if paired with a manufacturer recommended evaporator coil and a variable speed furnace or variable speed air handler, an outside unit could be rated as a 15 SEER system. Otherwise, the rating would be 14 SEER. As of January 2006, U.S. government regulations require all air conditioning manufacturers to produce residential central air conditioners with 13 SEER or higher. Between 1992 and January 2006, the minimum SEER rating was 10.As you might imagine, higher efficiency A/C equipment costs more to build. Why? For one reason, more efficient condensers and evaporators contain more metal in their extra coils. Additionally, to gain higher efficiency, the systems may have more complex technology such as motor speeds and electronics. If you are buying a new air conditioner, make sure you clearly understand the relationship between higher upfront costs and lower monthly utility bills of the more efficient equipment. The Energy Guide label clearly displays the SEER rating of all new A/C equipment.

In a furnace, a fuel is burned and the heat produced goes through a heat exchanger into to the air distribution system for the home or building. The blower and fan and ductwork carry the warmed air to the rooms where it is needed. A vent pipe or flue transfers waste gases to the outside air. Depending on where they need to be located within a structure, furnaces have different designs. These include conventional up-flow, horizontal, and down-flow designs.

On the brighter side, today’s central heating systems with gas are much more efficient than their predecessors. The heating industry uses a rating called the Annual Fuel Utilization Efficiency (AFUE) to measure the efficiency of converting gas into energy for heating. A high AFUE rating means the furnace can derive more heat from each unit of gas. This means both lower costs in utility bills and less environmental impact from emissions. Only twenty-five years ago, the typical gas furnace had an AFUE of about 65 percent. Currently, regulations of gas furnaces require them to exceed 78 percent efficiency. The AFUE range commonly seen is 80 to 95 percent, and the most efficient furnaces have an AFUE of almost 98 percent.

Maintenance: Plan ahead with regular maintenance, reduce the likelihood of emergency repairs, save energy, and prevent buildup of dangerous carbon monoxide.

Northwest Heating and Cooling encourages planning ahead through maintenance to prevent heater repairs. Why? If you wait until your heating system breaks, you will not only have to pay for the parts and labor, but most heater failures happen at the same time for everyone, during the first cold weather or times of intense use, such as the coldest day of the year. Since the repair companies are more likely to be busy then, you will be more likely to pay for an after hours repair or emergency trip charge.

In addition to annual maintenance from your heating contractor, be sure to change all air filters in your heating system according to the manufacturer’s directions. Make sure your ductwork is insulated if it runs through space that is not conditioned (i.e. in an attic instead of below the room ceilings.) Also, have your heating air ducts checked periodically for leaks. Sealing leaky ducts usually saves between 20% and 27% of all heated (and cooled) air, which would otherwise be lost through into un-conditioned space. Overall, skimping on regular maintenance and adjustment of your heating system can cause you to pay more each month on your utility bills due to wasted fuel and electricity.

From a mechanical viewpoint, the main components in a central heating system can last up to 25 years. Due to improvements in fuel efficiency in furnaces, their economic life is much shorter. Twenty-five years also happens to be longer than normal mechanical and economic lifespan of most air conditioners, so this leads to decisions on replacing all or part of your central HVAC system. If you are “on the fence” regarding repair vs. replacing your heating or HVAC system, you will want to talk about this while setting the appointment with Northwest Heating and Cooling.

Some situations call for heaters that do not require ductwork. Examples of suitable applications include one-room additions, offices, or garage apartments, and in a commercial setting, motel rooms. Although the equipment costs more than a portable space heater and needs professional installation, fixed ductless heat pumps offer some distinct advantages over portable space heaters. Because of their design, ductless heat pumps: provide heating and cooling with one unit, produce heat more safely than un vented gas portable space heaters and are usually more energy efficient that electric portable (“strip” heat source only) space heaters.

There are many different kinds of heat pumps, but they all operate on the same basic principle — heat transfer. This means that rather than burning fuel to create heat, the device moves heat from one place to another. There’s a key to making this all happen — heat naturally flows downhill. This means that it tends to move from a location with a high temperature to a location with a lower temperature. Pretty simple. What a heat pump does is use a small amount of energy to switch that process into reverse, pulling heat out of a relatively low-temperature area, and pumping it into a higher temperature area. So heat is transferred from a “heat source,” like the ground or air, into a “heat sink,” like your home.

One of the most common types of heat pumps is the air-source heat pump. This modern technology takes heat from the air outside your home and pumps it inside through refrigerant-filled coils, not too different from what’s on the back of your fridge. The air source variety is pretty basic, and you’ll find two fans, the refrigerator coils, a reversing valve and a compressor inside to make it work.

This system is more commonly known as an air-air heat pump, because it takes heat from outdoor air and transfers it to indoor air ducts. With the right kind of modifications, air-source systems can also work with other types of indoor heating systems.

The key to allowing the air-air heat pump to also cool is the reversing valve. This versatile part reverses the flow of the refrigerant, so that the system begins to operate in the opposite direction. So instead of pumping heat inside your home, the heat pump releases it, just like your air conditioner does. When the refrigerant is reversed it absorbs heat on the indoor side of the unit and flows to the outside. It’s here that the heat is released, allowing the refrigerant to cool down again and flow back inside to pick up more heat. This process repeats itself until you’re nice and cool.

By now, you’ve learned that air-source heat pumps use an outdoor fan to bring air over refrigerant-filled coils. Two sets of these coils transfer this heat indoors, where it’s then blown away from the coils by a second fan, and distributed through your home as cool goodness. Some air-source heat pump systems consist of a single packaged unit containing both sets of coils in one box. This box is then installed on the roof of a building with the ductwork extending through the wall. You’ll see a lot of larger systems for commercial buildings installed in this way. Home heat pumps are usually split systems with an outdoor and an indoor component installed through the wall. Depending on the type of system, there may be one or more indoor components to distribute heat.

Ground-source heat pumps are a little different. They absorb heat from the ground or an underground body of water and transfer it indoors, or vice versa. The most common type of ground-source heat pump transfers heat directly from the ground by absorbing it through buried pipes filled with water or a refrigerant. These liquid-pumping pipes can be either closed-loop or open-loop systems, and they operate pretty much exactly how they sound. In a closed-loop system, the same refrigerant or water circulates through the pipes repeatedly. In an open-loop system, water is pumped out of the underground water source, like a well or a man-made lake. From there, the heat is extracted from the water, and that water returns to the well or surface lake. More water is then pumped from the well to extract more heat in a continuous open loop.

If that’s not enough to blow your mind, consider the absorption heat pump — air-source pumps that are powered by natural gas, solar power, propane or geothermal-heated water, rather than by electricity. Absorption pumps can be used for large-scale applications, but are now available for homes on the larger side. The main difference between a standard air-source heat pump and an absorption pump is that instead of compressing a refrigerant, an absorption pump absorbs ammonia into water, and then a low-power pump pressurizes it. The heat source then boils the ammonia out of the water, and the process starts all over again.

When you go to check out an absorption heat pump, it helps to know how they’re rated. Manufacturers rate them using a measurement called a coefficient of performance (COP), which sounds pretty complicated. All you need to know is to look for a COP above 1.2 for heating and above 0.7 for cooling. And don’t worry, we’ll discuss ratings for standard heat pumps a little later.

Air-source, ground-source and absorption heat pumps are the most common kinds of heat pumps, but they won’t work in every situation. Read on to learn about special kinds of heat pumps.