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Mission: HVAC – Mission 3: Busting the Myths

by | May 30, 2018 | Mission HVAC

There are a lot of misconceptions when it comes to HVAC systems – and many of the common opinions don’t match up to the facts. For their third mission, our Mission: HVAC students shared some of the most common HVAC myths that they have come across in the field and set the record straight with the facts.

Jackson: Bigger is Not Always Better

Jackson Mission 3Throughout my life, growing up in the HVAC industry, I have heard quite a few misconceptions from homeowners about servicing and maintaining their equipment. I have been on several service calls with my father where we are the second company to look at it and they tell us what the previous company has diagnosed as the problem and that is not it at all. It is very important to me to educate the customer about their equipment as best as I can before I leave, because we will not always be the company they call if they need service again.

I think the most common misconception I hear from homeowners is that the bigger the system they have the more comfortable their home will be. The problem with that is when you over-size a system for a home and it doesn’t have to run as long as a properly sized system, that in turn decreases the amount of humidity removed from the home. This can cause the air to feel sticky and surfaces in the home to build moisture.

Another misconception that I have run into with homeowners is that they think that turning the thermostat to a much higher setting or even off while nobody is home will help with energy savings. This is wrong because, although the system is not on during the day your home warms up a lot and then you turn the stat back to where you want it to feel comfortable. You are better off to leave it set the same throughout the day so that the unit can cycle and allow the system to run properly and your home is already comfortable when you get home.

The last common problem I would like to mention is that homeowners will shut down supply registers in unused areas of their home to move more air to other locations in the house. This will cause an increase in static pressure in the duct work, which will then decrease efficiency of the overall system. If enough static pressure is built up in the duct work it could possibly blow apart the duct system causing even less air to flow into the space. The only true way to get more in different parts of the home is to redesign the duct system to put more air where you want it. Or even a multi zone system so that you can have all the air of the system blown where you need it.

It is very important as an HVAC tech to properly educate the customer. You may not always be the service man they use and they need to have a bit of knowledge of how their system operates so they are not swindled or pressured into buying things they don’t need. Everything you do should be in the customer’s best interest.

Stefan: Education Builds Lifetime Customers

Myth #1: Bigger is better when it comes to the size of my AC unit.
Fact: AC units do not just cool a chosen space, they dehumidify it. The short cycling created from an oversized AC does not allow the system to run for sufficient enough time to properly dehumidify the space. This lack of run time will severely affect the comfort levels of the conditioned space. The argument that an oversized unit will save the owner money is easily debunked with two simple facts: 1: An owner will be paying a higher initial price for a bigger unit, cutting into any nominal savings with efficiency. 2: The AC unit short cycling will also mean significant difference in starting and stopping of the system which ultimately will require more maintenance.

Myth #2: It saves an owner money to turn the AC off or set the thermostat very high when you leave the house, then turn the thermostat way down when they return home.
Fact: Setting a thermostat higher or turning the system off only means the system will have the workload from the pull down of the conditioned space greatly increased. Turning the thermostat way down will not cool the house any faster because most AC units only run at one speed, so setting the temp so low only makes the system run longer. The best way to tackle inefficiencies along these lines is to use a programable thermostat that will allow the system to rest when it is not needed, then to start the cooling process before people will be returning to the conditioned space

Myth #3: I can use ceiling fans to cool the house when I am not home.
Fact: Fans can cool an occupant of a room by moving air across a person’s skin. They can’t however cool a space because all fans do is move air around essentially wasting energy in an unoccupied space.

As a budding HVAC professional, I find there is no end to the value of educating a customer. First of all, education of a customer breeds trust and confidence. In a society full of contractors that will take advantage of any customer they can the value of earning trust is exponential. The ability to save a customer a dollar today and earn their confidence helps lend to the theory that they will be a customer for life.

Glenn: Let the System Do its Job

Myth #1: Closing off vents in unused rooms saves money in HVAC costs by not heating and cooling unused rooms.
Fact: HVAC systems are matched to the square footage of the home along with airflow rate through the ducts. Air flow is measured in CFM (cubic feet per minute). Closing off several vents can throw off the CFM rate of that system that was designed to operate at. Backing up air in the ducts causes the system to work harder. In addition, most people will forget about the return register in the room. Now you are pulling cold air back through the return and causing a negative pressure in the room, bringing in cold air through windows and any leaks from the outside – and there goes any cost savings.

Glenn mission 3

Myth #2: A house will cool faster with the largest A/C I can buy.
Fact: Installing a larger A/C unit than it was designed for will cause the system to short cycle. One of the functions of the A/C is to remove humidity. A larger A/C will cool off the home faster but will not run long enough to remove the humidity and will give you a clammy feeling. Buying the correct size will give you a more comfortable home.

Myth #3: Why do I need a furnace when my A/C fails to work, and needs replaced? The A/C is located outside.
Fact: Most customers don’t understand that the HVAC system is split into 2 sections. The condenser is located outside, and the evaporator is located with the furnace. And when its time comes to replace the condenser the furnace is more than likely the same age. Most HVAC dealers will suggest you replace the complete system, giving you a new, updated efficient system with a good warranty and a system that shouldn’t need to be replaced for at least 15 years.

Educating the customer makes a happy customer. Let the HVAC work as intended. Let the home warm and cool as designed. With homes being built tighter and HVAC systems becoming more sophisticated and expensive, making small cost saving changes may end up costing more in the long run and may damage the equipment.


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