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Additional Return Air and Return Air Runs |
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Solve most system airflow problems and increase efficiency |
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Insufficient return air is a very common problem for furnaces and central air conditioners. It is also a problem that can be easily cured. Ductwork, although it may look like artwork is really all based on air flow and math. If air ducts are not properly sized based on the amount of air needed to pass through them the system will not function properly or at its designed efficiency.
Every furnace or central air conditioner has a blower that pulls the air from within the home (The return side) through the heating and or cooling system and then pushes the air back throughout the home (The supply side).
The blower motors that heating and cooling systems use come in two basic types and a variety of sizes. The two types of blower motors are direct drive and variable speed. |
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Direct drive blowers typically have four or five speeds at which they can be preset to move the air throughout the home. The speeds are Low, Medium Low, Medium, Medium High and High. On a typical furnace, coil and condenser configuration the blower is set to operate on Medium Low for heating and Medium High for cooling. These settings are preset on the circuit board of the furnace and are engaged by selecting "heat" or "cool" on the thermostat. The blower speed settings can be adjusted by a trained technician to compensate for too much or too little air flow.
A variable speed blower motor automatically adjusts the blower speed based on several factors, like the stage the furnace or air conditioner is operating in, the static pressure inside the duct work and the temperature difference between the current indoor temperature and the desired indoor temperature. Variable speed blower motors use only a fraction of the electricity of direct drive motors. They are also more expensive and are typically only offered on higher end furnaces and air conditioners. Due to their very low energy use there are energy rebates and Federal Tax Credits available for systems that use variable speed blower motors or ECM motors. |
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Each of the two types of blower motors come in a variety of sizes. The standard sizes are 3 tons, 4 tons and 5 tons. A ton of air is equal to 400 cubic feet of air per minute of "CFM". With that, a three ton blower moves 1,200 CFM of air through a duct system. A four ton blower moves 1,600 CFM and a five ton blower moves 2,000 CFM.
Let's take a look at the the most common blower motor size, 3 tons. We know that a 3 ton blower motor has the capacity to move 1,200 CFM of air. The air the blower is moving must travel through the air duct system in your home and that's where the trouble is typically found. |
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Imagine a 12 lane highway with cars traveling in six lanes an each direction at 65 miles per hour. This highway is humming and cars are freely moving toward their final destination with no resistance. Until, the south bound lanes hit a toll plaza and the toll plaza has only three working tolls and none are EZ-Pay lanes. What happens, the southbound lane slows to a crawl and eventually backs up for miles because six lanes of traffic do not easily fit into three lanes of tolls. The next thing you know the north bound lanes begin to slow because they want to know what is happening to the south bound lanes. Before you know it neither lane of traffic is flowing to its capacity.
This is exactly what happens when your heating and cooling system does not have enough return air. The air gets caught in traffic and instead of moving 1,200 CFM of air your system is only moving 600 CFM and now the system is noisy, not heating or cooling properly and you are not comfortable in areas of your home. |
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What's the Solution?
The first step in solving air flow problems is to have a S.C.O.R.E.™ test performed on your system. S.C.O.R.E.™, which stands for Seasonally Calculated Operational Running Efficiency tells us exactly how efficient your system is operating at. In this case the system includes the furnace, coil and condenser along with the air filter, duct work, insulation and the supply and return registers. This is the true overall measure of effective efficiency of of the entire system.
Once the S.C.O.R.E.™ test has been performed we will know the effective efficiency of the system which we then compare to the manufacturer's rated efficiency of your heating and cooling equipment to determine how close to the potential your system operates at.
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The average system across the country is only operating at 57% of it's capacity!
Once we know the capacity we can perform further testing to determine how to enhance your system so that it will operate as close to it's potential capacity as possible.
The benefits you will receive by taking care of air flow problems include: quieter operation, improved airflow throughout your home, fewer repairs due to overheating and stress of the equipment, longer equipment life, lower utility bills and, best of all, greater comfort.
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