Before purchasing an HVAC system, it is important to know right size air conditioner or heating system for your house. A common mistake homeowners make is to purchase the wrong air conditioner size, sometimes too large of a unit for their home. This results in the homeowner spending more money on energy and operating costs than necessary.
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The most efficient way to determine HVAC system capacity will depend upon what type of heating or cooling you prefer.
When it comes to HVAC equipment, bigger isn't always better. You’ll see the best results, longest life and most energy efficiency from a system that's selected based off the proper air conditioner sizing for the square footage you want to cool and heat.
To help you identify the best fit for your home and budget, here are just a few of the factors you must consider when an HVAC replacement decision.
To determine what size HVAC unit works best for your home, it's important to know what type of heating or cooling system you currently have installed. If you are unable to identify what your current HVAC system is, then here are some general guidelines on what size unit is most often used for what type of heating or cooling.
Often, there will be a sticker on the outdoor compressor with information about what size unit it is. This sticker has all of the necessary information needed to determine what size system is currently in place.
If you are unable to locate this, then you can check what type of controls are being used for cooling or heating your home by checking what type of thermostat is being used as this will indicate what type of electrical system is currently in place.
Alternatively, you can also check what size system your home builder installed. Simply call your builder and ask what size cooling or heating systems were used for your new construction. Another option would be to contact a local HVAC contractor and have them inspect your home and what type of cooling or heating system is currently installed.
Once you have determined what size HVAC unit is currently in place, it will be easier to determine what size system you should install so as not to purchase too large a unit and lose out on energy savings.
Keep in mind that if your existing HVAC system is larger than what is needed, what size system you should install will be what is recommended by the manufacturer of your existing unit. It would not make sense to purchase an outdoor unit that is too small for what you currently have in place.
When shopping what size HVAC unit you should buy, what matters the most is what size house you have and what your desired temperature range is that you want to maintain throughout. Knowing how many BTUs are required for your home will allow you to make the best decision what size HVAC system you should purchase.
BTU stands for British Thermal Units. A BTU is what's required to heat or cool one pound of water by 1 degree Fahrenheit.
For example, your home's square footage total, including all floors and ceilings, is what determines what size what size HVAC unit you need. For every 500 BTUs required for your home, you will need approximately one ton of air conditioning or heating capacity (1 ton = 12,000 BTUs). Every degree above or below what the desired temperature is set at requires another 500 BTUs to increase or decrease.
There are two types of what size HVAC systems, single stage and two-stage. Single stage units are what you want for you home if your desired temperature does not go above what the normal setting is set at during summer or winter times.
Two-stage units are what you should get if there are times where temperatures get either hotter or colder than what the what size HVAC system you have will allow. If you live in an area where temperatures reach far extremes you need to add this into your residential load calculation.
The Manual J calculation is what HVAC professionals in the industry use to calculate what size unit you need. The Manual J sizing method includes measuring the cubic feet in your home, finding out what kind of attic insulation you have inside (R-11, R-13 etc.) and what your specific climate is like where you live. Here are the steps you should take to figure what Manual J sizing is perfect for your home:
1. Measure the outside air temperature of where you live and what the inside temperature averages during the winter.
2. Your manual J calculation requires knowing what your insulation is, what's included in your insulation and what climate zone you live in (hot or cold).
3. Look for what your insulation is and what the inside temperature averages on the Manual J calculation chart, and follow those steps to find what size unit you need.
4. Remember what features come with different sized units, so you can choose the perfect one that will fit all your needs.
When determining what size HVAC system is necessary for your home, it's important to get an accurate reading of what the square footage of your house will be. A square foot heating guide will make sure you're purchasing a unit that is big enough.
House Square Footage BTUs Needed 100 – 150 5,000 150 – 250 6,000 250 – 300 7,000 300 – 350 8,000 350 – 400 9,000 400 – 450 10,000 450 – 500 12,000 500 – 700 14,000 700 – 1,000 18,000 1,000 – 1,200 21,000 1,200 – 1,400 23,000 1,400 – 1,500 24,000 1,500 – 2,000 30,000 2,000 – 2,500 34,000There are online calculators that can help you determine what size HVAC system you need based on what you input into them as well.
One of the most important things to consider is what size HVAC system your home uses now . It is generally most economical to replace an existing system, especially if it is old and inefficient. If you have a new home, however, it may be most cost-effective to install a much larger system.
What size HVAC unit you need for your home also depends on what climate zone it is in . The closer you are to the equator, the warmer it will be year-round. If your area has mostly mild temperatures, you do not need an incredibly powerful unit to cool your home. However, if there are frequent heat-waves and you live in an area near the equator, your unit is going to have to be able to keep up.
What size HVAC unit you need for your home is also based on what season it is . If it is winter and you live in a cold climate zone, choose a system that will easily heat your home without constantly turning on and off. Try to make sure it will be powerful enough to heat your house during what is expected to be the coldest day of the year. On hot days, however, you do not want a system that can cool your entire home all at once.
There are many other factors that affect what size HVAC unit you should purchase for your home. Before deciding what system to buy, calculate what size HVAC unit you need based on what season it is and what climate zone your house is in. Also consider what size system it currently has so that you do not waste money or energy trying to cool or heat the entire home at once.
So what size HVAC unit should you get for your home size? For a single what size HVAC unit, what matters the most is what area of your home to run it in and what temperature range you desire throughout.
For average sized homes between 1,500 to 3,000 square feet, what size HVAC system you should purchase is what's called a three-ton unit. Depending on what your desired temperature range is will depend what size what size HVAC system you decide to get.
For every degree above or below what the desired temperature is set at will require what size HVAC system you should purchase to be an additional 500 BTUs.
For example, if your desired temperature is set at 71 degrees and what size what size HVAC unit you should get for your home size is a three-ton air conditioning or heating capacity system, then this what size what size HVAC unit should get what size HVAC system your home requires for that temperature range is 6,000 BTUs.
Owners, facility managers, and even the tenants of commercial buildings have a slew of responsibilities. Apart from managing staff and serving customers, they have an obligation to the actual structure and all its components – they need to make sure it stays in good shape. Failure to maintain and identify commercial HVAC system issues can lead to loss of income, and sometimes clientele.
Let’s face it: commercial HVAC is complicated stuff. If you thought residential HVAC systems were a head scratcher, you’re in for a not-so-pleasant surprise. That’s exactly why we came up with this wonderful commercial HVAC guide. Our hope is that it gives you the necessary information you need to stay on top of all things HVAC in your building so you can keep your commercial HVAC utility and repair costs low.
If you’re a business owner or facility manager in Maryland and you’re looking for commercial HVAC help, look no further than SuperTech HVAC for all your needs. Our qualified technicians have years of commercial HVAC experience. Whether you need extensive repairing and replacing, or simply have questions, we promise a minimally disruptive, charmingly educational experience.
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A commercial HVAC (heating, ventilation and air conditioning) system has the same objective as a residential HVAC system - to keep the building occupants cozy with high quality air in a 72-degree environment and humidity ranging from 40 to 60 percent.
The heating of air is often achieved through burning fuel (via gas, oil, or electricity). Cooling the air is the opposite (naturally), with a process that extracts hot indoor air and cools it through refrigerant or water-cooled systems, eliminating the extra humidity at the same time.
Ventilation systems use fans to introduce the necessary outside air, pass both the outdoor and re-used indoor air through filtration, and expel the building’s contaminated air. This keeps the CO2 at under molecules per million.
An effective ventilation system reduces odors, dilutes gases (like carbon dioxide), and prevents respiratory diseases from spreading. Without it, unwanted particles would render the air stale and increase mildew and bio-growth.
Link to AirTS
But how does your commercial HVAC system do all that? Let’s find out.
Controlling the climate in a commercial building requires three things: warm or cool air, a distribution method, and controls. The building’s cool air flows through the same ducts as the heated air and is regulated by the same thermostat. But the source will differ.
Most of the time, when the heating is activated in commercial HVAC, the burners create combustion gas that is transferred to a heat exchanger, which warms the air that is passed through. Sometimes, heat pumps transfer outdoor heat indoors. Air conditioners work the same way as heat pumps, but in reverse, transferring indoor heat outdoors.
Some commercial buildings use a boiler system to heat water, with hot water being carried through pipes installed in the walls, floors, or ceilings. You might not notice the structure itself warming, but you’ll feel the air being warmed.
Check it out – mechanical systems circulate a building’s air through ventilation, and the principle that warm air rises and cool air falls helps. There’s a constant induction and removal of air, which has been thermally altered in some cases.
To control all of this, commercial buildings can have simple, programmable thermostats that send various heating or cooling queues throughout the day, like in residential HVAC systems.
Commercial HVAC systems can also have direct digital controls (DDC), which are more complex. Commercial buildings benefit from more advanced controls for better energy efficiency and reliability. A central computer utilizes sensors to monitor and automate temperature schedules and even lighting operations.
Split systems are often connected to a building’s ductwork, like in a residential unit. Because they are ideal for residential buildings, they also work great for smaller commercial buildings, like small offices, restaurants, or convenience stores. Each area can be controlled via thermostat or through DDC.
The downside? For each space you want thermally controlled, you might need a separate HVAC unit set. This clutters the rooftop or space around the building. Zoning can be added to control different spaces, but it’s expensive.
If you wanted to heat and cool the different areas of a medium to large commercial building at the same time, you could go with a variable refrigerant flow system (VRF). VRF systems are relatively new to the US and thus uncommon. They utilize heat pumps or heat recovery systems and take heated air from one area to cool it and dump it to another that needs heating. We’ll touch more on this technology later.
So, where does this outdoor unit go?
A RTU, or rooftop unit, refers to a package unit located on the roof. Because of their location on flat roofs (no more than ten floors up), weather resistant housings protect the major components of the rooftop HVAC units. These compact, all-in-one HVAC units contain the compressor, condenser, evaporator, and blower.
Coming fully assembled from the factory, a rooftop unit is a type of air handler - it alters the air and circulates it through duct systems. Some RTUs only heat; others only cool, and some do both.
Inside the RTU’s rectangular casing, you’ll find an air hood that brings the outside air in to get conditioned. The air passes through dampers - rotating metal sheets that regulate air flow and push it through the filter, then to the coils which heat or cool the air. The fan that has been sucking the air begins to blow it into the duct system which carries it to the designated area.
Typically, an RTU will use a mixture of outdoor and indoor air to keep the CO2 at safe levels and avoid overworking the unit during very hot or cold days to save on energy.
VRF systems are relatively new to the US. Devised in Japan in the early ’s, VRF systems are very sophisticated commercial HVAC systems.
Simply put, VRF systems are ductless. Instead of ducts, they rely on heat pumps or heat recovery systems that send refrigerant from a central outdoor unit which houses all the compressors and condensers. The rate at which the indoor units receive refrigerant dictates how hot or cold each zone becomes. This allows for better temperature customizability.
The powerful yet quiet indoor equipment in a VRF system takes up very little space. This also means easy installation, as most indoor units can fit in a building’s elevator and no ductwork is needed.
VRF’s are up to 30 percent more efficient than ducted HVAC systems. This is because the varied compressor speed provides more accurate temperature adjustments, and no more energy is lost through ductwork like in traditional systems.
Unfortunately, VRF systems do cost more and require that a backup condenser be handy in case of a malfunction.
So how is this different from your home’s HVAC system?
Size
Commercial HVAC systems need to condition and ventilate larger structures than residential systems (unless we’re talking about Bill Gates’s house). You’d assume its components are larger – and you’d be correct. A residential system consists of a standalone unit, whereas a commercial system is modular; its components, however, are located together for easy installation and maintenance.
The size of a residential AC unit here in the US can go up to 5 tons. Modular rooftop units often come in 10, 25, and 50-ton units. The thermostats, condenser fans, compressors, evaporators, blowers, and dampers are all more powerful.
Location
In a residential house, the indoor unit (such as the furnace) is usually in the basement, closet or attic, and the outdoor unit is outside in the backyard or on the side of the house. This is referred to as a split system. Commercial buildings, on the other hand, sometimes have their HVAC units in a utility room in the basement, or somewhere beside the building, and quite often on the roof. These are all-in-one types, or packaged systems. As mentioned earlier, the rooftop provides a good barrier for noise, has ample space, and is out of the way.
Economizers
These may just be commercial HVAC’s best kept secret. They flush out building heat by bringing in cool outside air using logic controllers and sensors. Essentially, this is free cooling. Energy output is lowered, wear and tear on your HVAC unit is lessened, and ventilation is increased. The latter is especially important for older buildings that may lack the advantages of modern HVAC setups. Unfortunately, economizers are not available in residential systems.
Zones
Unlike most residential HVAC systems, commercial HVAC systems are a multitude of packaged units with their own thermostats so diverse indoor climates may coexist in one building. This gives each area independence from the other areas for complete customization. Technicians can repair one zone at a time to minimize disruption.
Ventilation
Due to a commercial building’s larger size, ventilation is more complex. There are more windows per square footage in smaller residential buildings, and having them open is an easy fix for stale air. However, fresh air intake and/or a designated mechanical ventilation system is commonly needed for commercial buildings. Moreover, commercial buildings may also include restaurants, fitness areas, laboratories, or other facilities that require strong ventilation to provide acceptable indoor air quality.
Drainage
HVAC systems extract humidity from the air during the heating or cooling process. This makes its way through piping and drips into a tray. The main difference is that commercial systems will have a bigger and more complicated network of pipes and drains.
Cost
The cost factors impacting commercial HVAC systems include brand, type of unit, building size, type of business activities, installation costs, etc.. According to Knapp Schmidt Architect, small businesses with one cooling zone can expect to pay between $3 and $4 per square foot for AC systems, while larger businesses can pay between $7.50 and $10.50.
Maintenance
Dirty Filters
You should change your filters four to twelve times a year (at least once a month), and we can handle those filter changeouts for you. Filters protect you from noxious particles, but they also protect the evaporator coil. A clogged filter will not allow air to flow through it, so the negative air pressure will suck air through gaps, cracks, and holes, and dirty the coil. A dirty coil cannot do its job properly - as its efficiency goes way down - and will work twice as hard to heat or cool the building’s air. This wear and tear takes years off its life.
Dirty Condenser Coils
You can spot this from a mile away. See, your split-system commercial HVAC unit has the evaporator coil on the inside of the building and the condenser coils on the outside. For packaged rooftop units, both coils are together in the containment, often on the roof. The condenser coils help release heat to the outside. When they are dirty - which can be an accumulation of dust, debris, grass, leaves, animal hair, and other things – the heat transfer is reduced. An EPA study showed a 21% drop in cooling efficiency as a result of as little as 0.042 inches worth of dirt on condensing coils.
Noises
Your commercial HVAC system could be making an entire symphony of noises. These should be taken as auditory indications that there are issues. Possible noises include - but aren’t limited to - squeaking due to a lack of lubricant in the motor, vibration from an unbalanced fan, thudding from an encumbered fan, rattling from the blower or loose ducts, buzzing or hissing due to a refrigerant leak, booming from a pilot light failing to ignite the furnace, and whistling from a boiler because there is trapped or blocked air. In this case, it’s vital to shut your commercial HVAC unit off and call a technician right away.
Malfunctioning Economizer
An economizer helps reduce energy consumption for cooling. If the outside air is cooler than the inside air and low in humidity, a damper opens to collect the air for circulation into the commercial HVAC system. If the economizer isn’t operating at a certain outdoor temperature, its air temperature sensors might fail or the dampers might be stuck. How common is this problem? Out of the 500 RTUs examined in a study conducted by the New Building Institute, nearly two thirds had malfunctioning economizers.
Clogged Drain
When the refrigerant is converted from a liquid to a gas in the evaporator coils, moisture is collected on the coil and forms condensation. The water is then supposed to flow down a drain. Without the proper maintenance, slime buildup may cause the drain to clog. If this happens, you’ll smell stale or moldy air coming from the vents, your air quality will drop, and the water will damage or rust the building.
Loose Evaporator Belt
A loose belt is hard on the pulley, reduces the fan’s speed, and will eventually freeze the coil. If your evaporator belt is loose, it will not last as long. Check for noise or loss of airflow for signs that your commercial AC’s belt is loose.
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So, how do you avoid all these problems?
Commercial HVAC maintenance is just as important as regular maintenance for your car or kitchen appliances. And like all maintenance, a small investment into prevention can save you a lot of money.
The biggest benefit to commercial HVAC maintenance is elongating the lifespan of each component. Because their functions intertwine, one bad actor ruins the show. The biggest issue with malfunctioning or clogged HVAC parts is that they put extra stress on the heating or cooling unit to perform. This is compounded with normal wear and tear and drastically reduces the life of your commercial HVAC unit by 8 to 15 years.
Consistent indoor air quality is important. Have you ever walked into an older building and felt your breathing affected? Or your eyes water? Unwanted particles have probably invaded the air, and a simple maintenance check could have easily found the dirty coils, filters, or blower parts. Poor indoor air quality is especially bad for the retail businesses that depend on positive in-store experiences from their customers to thrive.
Reducing costs is imperative when running a business. You certainly wouldn’t want to add high energy bills to that endless list of expenses. Preventative commercial HVAC maintenance can lower energy costs from 5 to 40 percent. Weakening parts due to poor maintenance not only shortens the lifespan of the equipment, but will lead to it working harder to accomplish its purpose.
An in-depth, customized plan is needed to maintain your HVAC system. Large commercial buildings have a huge complex network of HVAC equipment to properly heat, cool, and ventilate the air. This means you cannot rely on a cookie cutter HVAC maintenance program. Getting an HVAC service provider to help is crucial. They will consider things like climate, budget, and type of equipment to build a checklist.
How often you perform maintenance tasks will vary. Temperate climates will let you be more lenient, and harsher ones might necessitate monthly checks. Regardless, all commercial maintenance programs should include, at the very least, four annual services.
Commercial building owners, managers, and superintendents have a bad habit of waiting for something to happen before they give their commercial HVAC equipment attention. Don’t be one of them. Have a checklist like the one below available for yourself and your staff to avoid situations where you need to spend and lose a lot of money to halt operations and initiate HVAC repairs.
A typical HVAC checklist will include:
Remember that each building is different and requires its own checklist. If necessary, perform upgrades for better efficiency.
Commercial HVAC systems should be robust, durable, sophisticated systems of connections, structures, and moving parts.
It can seem daunting.
But reading this guide was a great first step. Now you know what to look for and how to prevent the issues that will cost you lots of money. Be sure to always talk to a professional if something seems off. They’ll ensure your commercial HVAC system is performing at its prime.
If you live in Maryland and think you have problems with your commercial air conditioner, RTU, VRF - or something with your commercial heating and cooling just seems amiss - give us a call. We're the area's best commercial HVAC repair company! Our team of experienced commercial HVAC technicians will provide you with a speedy and informative HVAC repair or replacement experience. Call us at (443) 219- or schedule online here.
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