Some Forced Air Cooling Basics
1. Your thermostat(1) sends a message to your furnace that it’s too hot.
2. Both the inside blower(2) and the outside fan(10) are activated. The condenser(11) or pump is also activated.
3. The condenser(11) circulates refrigerant(8) {freon or puron} via copper tubing from the inside evaporative coil(4) to the outside condensing coil(9). These coils are similar to a radiator in your car.
4. Hot air is pushed by the cool air and pulled by the inside blower(2) via the return-air(6) vents in the house through the filter(7). The filter(7) removes a portion of the dust, dirt, and allergen particles.
5. The inside blower(2) pushes this air across the heat exchanger(3) and through the evaporative coil(4). As the hot air passes through the coil(4) the refrigerant(8) absorbs the heat from the air, cooling it.
6. This cooled air(5) continues through your duct and vents into your home. This flow of air continues until the thermostat(1) sends a message to your furnace that it is cool enough.
7. Meanwhile the heated or evaporated refrigerant(8) continues to circulate back to the outside condensing coil(9). There the heat is removed from the refrigerant(8) as the outside fan(10) pulls air through the coil(9). As it passes through the coil(9) the refrigerant(8) releases its heats and travels back inside to absorb more. This flow also continues until the process is stopped by the message from the thermostat(1).
That’s really nice, right. But what does all of it mean to you?
This means there are many opportunities for in-efficiencies.
Some Cooling Problems:
1. The Thermostat
- Some require batteries to operate. If the batteries are not changed at least once every year they can cause erratic behavior in your furnace and/or air conditioning.
- Because thermostats operate on electrical power there is a possibility of wire and connection corroding or shorting out.
- Lower end thermostats are often disrupted by static electricity. There is a performance difference between retail store and HVAC professional thermostats.
2. The inside blower
- As you can see from the diagram on the previous page the filter can only remove a portion of the dust and allergen particles. The remaining particles get pulled into the blower. Here there are plenty of places for those particles to get trapped in the motor, causing it to work harder and use more electricity. This causes additional wear and tear on the motor and can shorten its life span.
- In a new home sheetrock dust can be a major contributor to the particles being pulled into your blower.
3. The heat exchanger
- During the cooling season your heat exchanger’s only function is to collect dust, dirt and insects. This can affect the operation of your evaporative coil.
4. The evaporative coil
- This radiator like structure is comprised of aluminum fins that have a tendency to collect the dirt, dust, and allergen particles that have not been removed by the filter or trapped in the heat exchanger. When these particles collect on the coil it reduces the airflow and insulates the coil reducing its ability to absorb heat.
5. Return air
- As the air circulates through your home it collects additional dust and allergen particles to be passed through the system. This becomes important in the later on.
- In-adequate return airflow passes less warm air through the evaporative coil, creating less heat to be absorbed by the refrigerant causing it to freeze.
6. The refrigerant line
- This pliable copper piping carries refrigerant from the evaporative coil to the condensing coil. A portion of it extends from the outside of the house to the condensing unit. It can be damaged by humans or gardening equipment.
7. The outside fan
- As with the inside blower the outside fan is pulling air through coils. When the condenser coil has collected dirt and debris it causes the fan to work harder and use more electricity. This also causes additional wear and tear on the fan and can shorten its life span.
- Because this equipment is outside it can be impacted by weather.
- The controls to this equipment are electrical and can wear out over time and use especially when the air conditioner turns on and off frequently.
8. The compressor (pump)
- If your refrigerant level is too low it can cause your system to freeze. This “freeze” condition is easily detected by the presence of ice along the refrigerant line and/or the evaporative coil. Low refrigerant levels are generally caused by the presence of a leak or under charging at installation.
- If your refrigerant level is too high your system runs for long periods without cooling your home. High refrigerant levels are generally caused by over charging at installation or a subsequent service.
- Again the controls to the equipment are electrical and can wear out over time and use especially when the air conditioner turns on and off frequently.
9. The condensing coil
- This is another radiator like structure comprised of aluminum fins that have a tendency to collect the dirt, dust, and debris that is present in your outdoor environment. When this debris collects on the coil it reduces the airflow and insulates the coil, reducing its ability to release heat.
- On some units the aluminum fins are exposed. These fins are easily bent causing an obstruction of airflow and reducing its ability to release heat.
- It is recommended there be 2 feet of clearance around your condensing unit to allow for adequate airflow.
10. The filter – believe it or not this is a tricky one
- First we will address the obvious. A dirty filter reduces the return airflow and by now you know what types of problems this can create.
- The tricky part. Thick, dense, heavy duty, high quality, allergen reducing filters definitely reduce the particles traveling through your system. Of course in order to accomplish this the return airflow is also reduced. With the information you now have, this one is for you to decide what you want to do. Indoor air quality can be improved by opting for electronic or ultra-violet air cleaners.
Some Cooling Solutions:
1. Change or clean your filter regularly. A standard filter should be changed at least every two months during system use. Yes that means during the cooling season as well. The thicker, denser, heavy duty, high quality, allergen reducing the filter is the more often it will need to be replaced or cleaned. If you have hair fur-bearing pets inside the home the filter should be cleaned or changed more often.
2. Indoor air quality can be improved without compromising the operating efficiency of your system by opting for electronic or ultra-violet air cleaners.
3. Have your system professionally cleaned and inspected (tuned-up) annually. Make sure this cleaning and inspection is very thorough. It should at least address each of the potential problems mentioned here.