Before installing a new system, proper “Manual J” load calculations should be calculated on the area in which heating and air conditioning is needed. These load calculations measure how much heat is leaving the building during the wintertime and how much cooling is leaving the building during summertime. These loads take into account variables such as your geography’s climate, the volume of the area needing air conditioning, how much heat is generated from the people and equipment in the area, the types of walls, windows and ceilings in the area, as well a myriad of other factors.
If your unit is old and you are looking to replace your current unit, it still may not be a bad idea to have your building loads re-calculated to account for any changes your building may have undergone over time.
For those who do not wish to use a contractor or find the online Manual J calculators too burdensome, there is an easier – but less accurate – method to calculate how much air is needed. According the Department of Energy, structures in South Carolina’s Upstate need between 20-30 BTU’s per hour per square foot. Thus, if your space is 3,000 square feet, you would need between a 5-ton system and a 7.5-ton system (1 ton = 12,000 BTUs), depending on the efficiency of the system and how weatherized the building is.
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What size system do I need?
What are some easy ways to reduce my energy bill?
How often should I have my unit checked?
What does SEER mean? Is it accurate?
How often should I change my air filters?
Why is R-22 so expensive?
One of the easiest ways to reduce your HVAC bill is to use a programmable thermostat. A programmable thermostat will allow you to keep the home or building at a comfortable temperature while you are there and adjust temperature accordingly for when you aren’t there. According to Energy Star, a programmable thermostat can cut up to $180 per year off your energy bill.
Another easy solution is to “weatherize” your home or building. This can be done by sealing any cracks or spaces in which air can permeate, increasing insulation and adding blinds, shades or window tint to decrease sunlight emitted.
Regular tune-ups, using a high-efficiency unit and changing filters regularly will also help reduce your energy, which will be mentioned later.
For residential homes, we recommend a quarterly filter change and a semi-annual inspection – once in the Spring, once in the Fall - to clean coils, check refrigerant levels, and make sure all parts are working properly. For commercial and industrial buildings, quarterly check-ups are more optimal. While paying for a service agreement may seem like a waste of money in the short run, it could save you thousands of dollars in repairs in the long run.
SEER, or Seasonal Energy Efficiency Ratio, measures how efficiently a unit operates. This is calculated by dividing the sum of all cooling outputs (BTU/hr) into the sum of all power outputs (watts). To qualify for an Energy Star rating, a system must have a SEER rating of at least 15.
While manufacturers like to boast their high SEER ratings, it is important to note that SEER is calculated at test conditions of 82°F. Additionally, the SEER rating estimates the average efficiency of an air conditioner throughout the entire duration of the cooling season. Thus, it becomes unreliable and inaccurate when measuring your system’s efficiency when the summer temperatures are well into the 90s. Moreover, if your condenser or evaporator are not properly sized, the SEER rating can be negatively affected.
Instead, a more reliable measure would be the Energy Efficiency Ratio (EER), which is essentially the same as the SEER rating, with the exception that EER measures efficiency only under the specific operating conditions under which it was measured.
As you may have noticed, the cost of R-22 has skyrocketed over the past few years. This is due to the “phase-out” of the refrigerant, which will stop being produced completely by January 1, 2020.
Because R-22 is a hydrochlorofluorocarbon (HCFC), it is considered to have a high Ozone Depletion Potential (ODP) relative to other refrigerants since it contains chlorine. While there is no “drop-in” refrigerant that is tantamount to R-22, R-410A (an HFC) is regarded as having properties most similar to R-22.
While this question usually depends on who you ask, it actually matters more about who lives or works in the space. Generally, most people in the HVAC field recommend changing air filters in offices and homes about every 3 months. However, this probably isn’t often enough if you’re in an area where allergies and pet hair are the norm, in which case you may want to change filters every 30-60 days.
Additionally, pleaded filters located in the returns of large roof top units on industrial buildings are often going to need to be replaced monthly at the least. Given all the dirt, debris and fumes released in these industrial plants, indoor air quality is paramount, and the easiest way to do this is through regularly scheduled filter changes.