Cooling Services – How does Eco Performance Builders optimize cooling systems?
In a lot of California’s climate, cooling is a major comfort and energy concern. There are a few options for cooling your home – Air conditioning systems, Evaporative Coolers (Swamp Cooler) and Whole House fans are the main options used in our California climate. The most common of these is the Air Conditioner, more specifically, the split system air conditioner.
Here at Eco Performance Builders we take air conditioning very seriously. When we install, replace or upgrade a system, we commission the unit by testing its performance. In our systems:
The Airflow Must Be Adequate.
- Airflow for our climate should be 400 – 500 cfm per ton of air conditioner.
- Air conditioning systems rarely have this amount of airflow which lowers the efficiency, life and effectiveness of the air conditioning system
- System air flow is dependent on matching the best air handler with the compressor and static pressure. Static pressure is the most overlooked portion of these two by technicians. The higher the static pressure the lower the airflow. Correct static pressure is maintained in a system by installing engineered duct systems based on ACCA manual D. We engineer all of our duct systems using manual D and check our static pressure and airflow to assure it is correct. Another cause for high static pressure is dirty filters and undersized return air grilles and ducting.
- We use engineered air grilles to deliver the correct airflow without the air directly hitting people and they are very quiet. Most contractors put in cheap air grilles that do not deliver air correctly and are very loud.
The Refrigerant Charge Must Be Correct
- This detailed test is based on the outdoor and indoor temperature, humidity and the manufacturer’s specifications. It is a test that is not done correctly by a lot of technicians. Most technicians only check the charge at the unit and dismiss the other readings.
The Duct System Must Be Tight (not leaky)
- California homes leak on average of 30%. This leakage is cooling and heating your attic and crawl spaces which probably isn’t where you want your hard earned money going. Duct leakage also brings in contaminants through the air return system which goes directly into your home. Leaky ducts are sometimes easily fixed and can increase system efficiency, indoor air quality and home comfort.
The Ducts Must Be Sized Correctly
- They must not be bigger than necessary so we minimize heat gain and heat loss
- For static pressure so the airflow is correct.
- Ducts should run to the shortest points possible in rooms as well.
The Air Conditioner Size Must Be Correct.
- We size our systems using ACCA (Air Conditioner Contractor’s of America) Manual J guidelines. It incorporates room by room cooling load calculations taking into account size, insulation levels, building materials, orientation and climate region. Correct system sizing is rarely done by today’s technicians and is commonly performed as a “rule of thumb” technique where they will estimate 500 square feet per ton of air conditioning. This commonly results in system over-sizing, which impedes system efficiency, comfort and life of the unit.
- A correctly sized system will run without stopping on the hottest day of the year. When a system is over-sized it will constantly cycle on and off during the hottest day and every other day. When the system is running for a longer duration it is running at top efficiency but a unit that is starting and stopping is running at a low efficiency. It is like comparing your gas mileage on the freeway vs stop and go driving.
- A correctly sized system uses far less electricity than a larger one. When it is running it uses less electricity at the A/C compressor (outdoor unit) and the fan unit (inside) because they are both smaller (correctly sized).
- We like to make sure that all of the cost effective home performance work, like air sealing and insulation, have been done. If these measures are going to be taken we want to size the system with them in mind. We can do all of this work at the same time ensuring you will have a great performing system in a great performing home.
Room By Room Airflow Must Be Precise
- The ACCA manual J room by room load calculations give us the airflow needed for each room.
- We adjust the airflow to each room using dampers and a high quality flow meter for each register.
Frequently Asked Questions: Air Conditioning
1) How does an Air Conditioner work?
Air Conditioners transfer heat from inside to outside by means of refrigerant and a duct system. Air is pulled into the duct system,
from your home, and into the evaporator coils (the inside part of the AC that is attached to your furnace). At that point the air is cooled and then distributed through the supply duct system back to each room. But how is the air cooled?
The refrigerant runs in a loop from the outdoor part of the AC (condenser/compressor) to the inside part next to the furnace (evaporator) and then back again. When it arrives at the evaporator (inside) it’s a cool condensed liquid state. It passes through the evaporator coils and cools the air that is passing over the coils. How? The pressure of the refrigerant inside the coils is allowed to drop, making it start to evaporate into a gas. As it turns into a gas it absorbs heat from the surrounding air. As it leaves the evaporator it is a gas that is cool and low pressure. At this point it goes to the compressor (outdoor unit) and, well, is compressed. As it compresses, it becomes a high pressure hot gas. Then it goes into the condenser (2nd part of the outdoor unit) at which point the outdoor fan and metal fins dissipate the heat at which point it “condenses” back into a cool liquid state. It is then run back to the evaporator inside to complete the cycle.
You may have heard of heat pump technology (all in one electric heating and cooling). The heating side of this is simply the above process run in reverse.
2) Why and when should I upgrade my Air Conditioner?
First of all, do you use your air conditioner enough for it to be worth it? Some people only use their ACs on 5 of the hottest days a year. Some people set the thermostat to a constant below-average temperature (75-85) for the summer months. And then there are homeowners who use it sparingly because they know the system is costly and inefficient. The idea is to have a system that is efficient enough that you can use it guilt free and worry free. If your duct system is sealed, sized correctly and well insulated and if your Air Conditioner unit is a decent SEER (13 or above rating) and sized correctly then you do not need to use it sparingly. Keeping your home comfortable does not need to cost a lot of electricity or money.
Secondly, it is important to take a look at the cost effective projects first. Ask yourself: Are my ducts leaky? Is my home leaky? Do I have poor insulation in my walls, floor and attic? If you answered yes to any of these, then these should consider at the same time or before looking to replace an AC. These are not only more cost effective ways to save energy and improve comfort, but by performing these upgrades you will be reducing the size of an AC that the home needs.
3) Some rooms are not getting enough cool air when my AC is on. Some are getting too much. Why is this?
Balancing a duct system is the process of distributing the total air flow in the exact proportions needed for each room. This is not something that should be estimated or guessed. Measurements and modeling can be done that determine exact target air flows on a room by room basis. These are measured in cubic feet per minute (CFM). Dampers can then be installed in the ducts in each duct line. These can be finely tuned until the exact target CFM airflow is measured coming out of each room’s supply register/vent. This is it takes to balance a system.
4) What if I have a correctly sized AC but over sized furnace?
This is never recommended, but unfortunately occasionally happens. Many HVAC contractors either don’t know better, or just want to make a quick buck and get out. They get called in because an AC is not functioning properly or because the homeowner has decided it’s too old and finally time to replace. Far more often than not, the furnace is very over sized for the home. So the HVAC contractor has a few decisions at this point. Should they: a) install a correctly sized AC but not worry about the large furnace size (inefficient and not comfortable), b) install an over sized AC to match the existing furnace (very inefficient, uncomfortable and perpetuates the problem) or c) recommend a correctly sized furnace to match the AC size. The proper recommendation should always be “c”. However, this is not always in the homeowner’s budget. Or maybe the contractor is worried he will lose the job. So what frequently happens is that an over sized AC is put in to match the over sized furnace and the problem never ends.
Read “Efficient Air Conditioning” article for information that answers these questions:
- What is SEER? What is EER?
- What is the right size AC for my house?
- What is the best refrigerant for my Air Condtioner?
- How do I find out my Air Conditioner size?
- How often should my Air Conditioner be serviced?
- Is a 15 SEER or above efficiency rating worth the cost?
- What other types of ACs are there?
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- Energy Audit / Home Performance Analysis:
- Air Sealing
- Duct Systems
- Indoor Air Quality
- Crawlspace Sealing
- Green Building