When it comes to investing in a new HVAC system, the answer of which system to buy is about “as clear as mud”. Purchasing any new appliance can be overwhelming, especially if it breaks suddenly. When it comes down to spending your hard-earned money and your everyday comfort, you clearly want to make the right choice.
There are so many different options to choose from when it comes to equipment: type, size, warranty, brand name, gas vs. electric, efficiency rating, features?!?! Even more questions come up as you meet different contractors, each telling you something a bit different. This guide is meant to help you as the homeowner: understand the equipment, know the lingo, and learn what it takes to make a wise and informed decision when purchasing a new HVAC system.

System Types

The two basic configurations of residential HVAC systems are split systems and package systems.

Split System

Consists of an indoor unit and a separate outdoor unit  connected by wiring and refrigerate lines

Packaged System

Consists of one unit outside, containing both the inside and outside components, packaged in one box

Variations

There are different variations of split and package systems, mainly depending on which fuel you choose to use. The main choices here would be electric, natural or propane gas, or both.

Air Conditioner– Designed to dehumidify and extract heat from your home. Utilizes electricity only.

Heat Pump– Like an air conditioner, heat pumps are designed to dehumidify and extract heat from your home. A heat pump, however, uses a reversing valve, which allows it to draw heat from the outdoor air in the winter time. Heat pumps are efficient at removing heat down to around 35-40 degrees. At that point, resistance heat or other means must be used to supplement. Utilizes electricity only.

Electric Resistance- Resistance heat transmits electricity though heating elements. As the elements heat up, the system’s blower is activated to distribute the heat through the air ducts. Electric resistance heat is often more expensive than heat produced by other means.

Gas Furnace- Designed to use combustible fossil fuels such as natural or propane gas to heat your home. Combustion occurs through burners inside a heat exchanger. Spent gasses are then expelled from the furnace. The system’s blower passes over the heat exchanger before it distributes air into the ducts.

Dual Fuel- Designed to utilize both electricity and fossil fuel. Uses a heat pump for primary heating down to the balance point (the temperature at which the heat pump begins to struggle to keep up), usually somewhere around 35-40 degrees Fahrenheit outdoor temperature.  The furnace then takes over to provide secondary heating.

Split System Components 

Remember that split systems are composed of separate indoor and outdoor sections. The indoor components are connected directly to the air ducts and contain the blower used to distribute the air. The outdoor portion contains the “heart” of the system, the compressor. The compressor is what pumps refrigerant through the components of the AC system, removing heat and humidity.

Every AC system contains two coils: the evaporator coil (indoor portion) and the condensing coil (outdoor portion). These coils are connected by copper refrigerate lines. This is a sealed system that contains a certain amount of refrigerant required for proper operation. Systems have service ports allowing technicians to check the amount of refrigerant in a system, adding or removing as necessary. The amount of refrigerant varies from system to system due to coil sizes and the length of copper line sets connecting them.

Outside components are usually fairly easy to spot. They are the noisy cubes sitting outside everyone’s house. These components are called condensers and are either strictly air conditioners or heat pumps. The differences in appearance are minimal and the untrained eye couldn’t tell the difference. An easy way to tell is if it runs during the winter, it’s probably a heat pump condenser, unless something’s wrong :)!

Depending on which fuel variation you choose, your split system could include these indoor components:

Air handler– contains the blower and evaporator coil

OR

Furnace– contains the blower, gas components, and heat exchanger

Coil– evaporator coil paired up with a furnace to complete the indoor section of the AC system; usually connected in between the furnace and the supply air duct

Package Systems

Package systems take these components and group them together under one housing. This is installed as a central unit on the outside of your home. It attaches to your duct system through the exterior wall. Package units vary just as split systems do. The most common are:

Package Heat Pump

Package Gas

Package Dual Fuel

All three of these variances contain the components needed for both heating and cooling operations. The only component inside the home would be the ductwork, which attaches directly to the unit, and the thermostat.

So now that you know the basic differences in equipment, we can move on to efficiency and what makes two seemingly similar looking systems much different.

 

Sizing

Equipment sizing is probably the most important factor when choosing equipment for a home. This can only be done by performing a Manual J load calculation. Through a complex series of calculations and inputs, the HVAC designer is able to analyze all aspects of the thermal characteristics of every wall, floor, ceiling, door and window. An HVAC load calculation also takes into consideration other factors such as the home’s geographic location, orientation to the sun, envelope tightness, duct leakage, lights and appliances.

Equipment is sized in tons (as in 12,000 BTU/ton). Residential systems vary from 1.5-5 tons. Keep in mind, bigger is not always better. A load calculation can tell you exactly what size your home needs, keeping energy costs down.

 

Efficiency

SEER Rating

System efficiency is something we might not think too much about when purchasing new equipment. But, it’s something you’ll definitely think about every month thereafter. Equipment efficiency is most often measured in SEER (Seasonal Energy Efficiency Ratio) rating. The higher the SEER, the better the energy performance, the more you save. The Dept of Energy has set the minimum SEER rating for new equipment at 13. This rating will be raised to a minimum of 14 effective January 1, 2015. Units with a higher SEER rating cost more up front, but can save hundreds over the life of the unit.

*A split system’s SEER rating is derived from matching the outdoor unit and indoor units. These ratings can vary depending on how they are matched up. Ask your contractor for these ratings before you buy.

Air Ducts

Purchasing new equipment with a high efficiency rating doesn’t guarantee energy savings. Your home’s air ducts are nearly as important as the unit itself. Leaky, restricted, or improperly sized duct could result in significantly higher energy costs.

Repairing VS Replacing

In order to take advantage of a new high efficiency system, you must take your air ducts into consideration. EnergyStar reports that,

“In a typical house, about 20 to 30 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts. The result is higher utility bills and difficulty keeping the house comfortable, no matter how the thermostat is set.”

Taped seams can become dried out and connections can become loose over time. Duct sealing may be a good option for air ducts that are still structurally intact but have leakage. However, if your air ducts are 15-20 years old or in poor condition, you may looking at replacement. Ask a professional you trust to take a look and give a recommendation.

 

Brand Name

National advertising is prevalent for almost every commodity for the home. That being said, HVAC equipment manufacturers rarely do much advertising themselves. For the most part, you rarely hear of what brands of equipment are out there.

All HVAC equipment is basically the same components in different shells. Some manufacturers do have brand-specific patented components in them, like Trane’s spine-fin coil (pictured), but the majority of them are the same inside. Much like the auto industry, HVAC equipment manufacturers put out basically the same product under different names. Did you know that Trane, American Standard, and Ameristar are all subsidiaries of the same company, Ingersoll Rand?

So, does it really matter whose badge is plastered to the side of the box? Not really. What really matters is the company that will stand behind the product. Do they stand behind the products they install? How about the availability of parts when it breaks? Can it be fixed today? tomorrow? or in the next week? What about the warranty? Will it be out-of-pocket expense for these parts or are they covered? Good questions to ask before you buy.

 

Warranties

Equipment warranties differ from equipment variety and brand name. Most manufacturers offer a 10 year registered parts warranty with new equipment. Stainless steel heat exchangers often have either a 20 year or lifetime warranty. Refrigerant is usually not covered under warranty. Labor warranties are usually offered for a fee. Be sure to register all new equipment within a 30 day period to take advantage of the full warranty. Check with your contractor on warranty specifics.

About Your Heating and Cooling System

1 Bigger Is Always Better

Often families seek to purchase a bigger unit when they feel that their
current one is not doing the job. However, upsizing is often not the correct
solution. In fact, a unit that’s too big can actually cause your system to
cycle on and off more frequently without evenly distributing air, leading
to just as many problems as one that is too small.

2 Ductwork Doesn’t Play a Big Role In System Efficiency & Performance

Inconsistency among room temperatures, extended heating and cooling times
and high energy costs can all be attributed to improperly sized or leaky
ductwork. Consider ductwork to be one-half of your home’s heating and
cooling system. So, if your ductwork is not designed to distribute air evenly,
is improperly sized or is leaking air in several places, then your entire
system is performing at limited efficiency. To view more information about duct sealing, be sure to check out our article here.

3 Summer Comfort Can Be Achieved Just By Lowering the Thermostat

Every Middle Tennessee resident knows that our trademark humidity often
presents more of a comfort challenge than our 90°-100° temperatures.
Don’t touch the thermostat in hopes to get rid of it this Spring and
Summer, however. By its definition, an air conditioner—when operating
properly—is designed to both lower the temperature in your home
and reduce the humidity. If you’ve felt comfortable at 75° in your home
previously, but this year the air feels sticky, turning it down to 73° isn’t
going to make it better. More than likely, your system needs a maintenance
visit to clean the coils and check your refrigerant charge.

4 Preventative Maintenance Is Just a Sales Gimmick

Just like faithfully changing your car’s oil, research has proven that your
regular tune-ups can extend the life of your system.
To put that figure in perspective, it means purchasing a brand new unit less
often, equating to savings of thousands of dollars over a lifetime. That’s
money well spent on other things, like vacations or home improvements!

5 Almost Anyone Can Install An HVAC System

At first glance, it may seem fairly straightforward to install a HVAC
system—but guess again. It’s imperative to choose a trained professional
that will take the time and care to not overlook details that could turn into
problems down the road. Firstly, any contractor worth his salt will both
inspect your current equipment, duct system, and electrical connections as
well as run a load calculation on the area of the home the system serves.
Taking these steps ensures your unit is properly sized and up to current
local building code. Secondly, installers will be sure to put in your new
system correctly to make sure your family is both safe and comfortable.

 

Heating and cooling our homes account for more than 50% of our energy cost.  We cringe when we see that heating bill in the cold winter months, when we know that our system has ran almost continuously.  In the winter, we take special effort to ensure that every window sill and door threshold is sealed up tightly.  We insulate our attics to capacity, going over every weatherization technique known to man.  We want every last bit of warm air to stay in our home.  The last thing you want to happen is to let that precious heat escape.

With this in mind, think about the duct work supplying your home.  Do you know that almost every duct system has leaks?  Even a well installed duct system can begin to leak overtime at joints and seams.

A proper load calculation actually takes air loss into consideration.  Air loss can be anywhere from around 5% up to 20% and more.  Imagine what that could mean for unit efficiency.  Units will begin to run longer, rooms may become different temperatures, and you may even notice more dust in your home than usual.  This is where duct sealing comes into play.  The goal here is to minimize the leakage.

The following is documented for your knowledge of how duct sealing actually works.  If you have any questions regarding duct sealing, please feel free to contact us.

 

Most HVAC Ducts Are Not Properly Sealed

 

Figures 1 & 2 show a common HVAC duct system.  This is an every day example of duct leakage.  Though it may not look like a lot, the evidence shows.  If you look closely, you may notice gaps where the duct that attaches to the unit.  Though it has fasteners securing it, it’s not enough to stop the the high pressure air coming out.

The Supply Duct

As you can see, the duct work here has been patched (figure 2, center).  The outline of the patch can be clearly seen on the yellow insulation that covers it.  The dark outline is dirt from the air stream.  The duct work shown here is the supply, which carries the conditioned air to the rooms in your home.  The air flows out of the supply duct as positive pressure.

You might be thinking, “Why is there dirt in the conditioned air?”.  There could be a couple reasons for this: one being that the filter is allowing contaminants through, the other would be holes and gaps in the return duct.  As the blower inside the unit pulls a negative pressure through the duct, it allows contaminants to make their way into any holes left open.

The Return Duct

Figure 3 shows the return duct.  It was left in the same condition as the supply.  Unsealed, it was allowing all the dust and dirt from the attic space into the air stream.

Properly Sealed Ducts

Ducts can be sealed in a few different ways, two of which are used most often: UL approved mastic tape and liquid mastic paste.  In this case, we used the UL approved tape in addition to some silicone caulking for the larger gaps.  After a little surface cleaning, the tape sticks well.  After passing a squeegee across the tape, it bonds securely.  Every seam and hole in the duct must be sealed.  Even the tiniest of holes allow contaminants into the air.  Figures 4 & 5 show how the duct was sealed.

Though it takes some work, you will notice a difference. Some improvements could be:

• Decrease in Dust
• Decrease in Allergens
• Increased Airflow
• Decrease in Smells
• Increase in Equipment Efficiency
• Decrease in Energy Bills
• Cleaner Coils Increase Life Expectancy of Equipment

If you would like more information on duct sealing please let us know. We would be happy to take a look at your system and give you our recommendations.