HVAC Encyclopedia by Allied AC: Comprehensive HVAC Knowledge

The Basics

The term HVAC (Heating, Ventilation, and Air Conditioning) is used to describe the air conditioning and heating industry as a whole (Residential, Commercial, and Industrial).

There are many different terms used to describe Air Conditioning and Heating systems, here are a few:

• A/C system
• A/C and Heating system
• Straight Cool system
• Heat Pump system
• Split-System
• Package Unit
• Mini-Split system
• HVAC system

The plain fact is, all Residential air conditioners are supposed to be installed with heat in them. So, all of these terms refer to the same thing. The only major difference of any system is how it heats (heat strip, heat pump or gas).

Air conditioners cool our homes using refrigerant (Freon) to absorb the heat inside the home, and then release the heat outside of the home. Also, as a natural consequence of the way an air conditioner works, whenever the system is cooling, it is also dehumidifying the air inside the home.

Indoor comfort is achieved by controlling the temperature and the humidity inside the home. And, while the indoor temperature is always important, indoor humidity control can be even more important, especially in high temp/high humidity climates, such as ours.

Humidity (for A/C purposes) is the amount of water vapor present in the air, inside your home. Humidity is measured in % of Relative Humidity (RH).

• Most people feel comfortable between 45% – 55% RH  ( @ 76°- 80°F )
• Mold and mildew are able to grow above 60% RH

Have you ever walked into a mall or big box store and your eyes and sinuses start to get dry?

This is because these places run their A/C systems 24/7, and this tends to over-dehumidify these spaces (below 45% RH).  

Have you ever been in an Air-Conditioned home or business where it feels kind of cool but not comfortable? You look at the Thermostat and it says 75°F inside, so why doesn’t it feel comfortable?

The reason it doesn’t feel comfortable is because of high humidity conditions (above 55% RH).

There are a many reasons why high humidity conditions can occur inside a home, here are a few major ones:

• Improper installation of the system
• Lack of maintenance and cleaning of the system
• Over-sizing of the system
• Old and/or leaking ductwork
• Old and/or leaking windows, doors, etc.

Capacity Ratings of A/C and Heating Systems (tonnage)

• The capacity, or size, of an A/C system, is rated in tonnage
• The tonnage of an A/C system is a measure of how many square or cubic feet the system is capable of cooling and heating  (this can also be affected by: type of construction, windows, insulation, etc.)
• Residential systems come in 7 different tonnages: 1.5 ton, 2 ton, 2.5 ton, 3 ton, 3.5 ton, 4 ton, and 5 ton
• Contrary to some beliefs, installing a bigger A/C system is not always better
• It is very rare that a home needs a bigger system than the square footage calls for
• The tonnage of an A/C system only refers to the capacity of the system, NOT the efficiency

Efficiency Ratings of A/C and Heating Systems

• The efficiency of an A/C system is rated in SEER (Seasonal Energy Efficiency Ratio)
• A higher SEER system will use less electricity than the same system with a lower SEER rating
• A/C and heating systems are available in an ever-growing selection of efficiencies
• The SEER of an A/C system only refers to the efficiency of the System, NOT the capacity

Twenty years ago, a 12 SEER A/C system was the height of efficiency, as of Jan 1, 2017 every new system must be at least 14 SEER, and the highest rated systems are around 21 SEER, for a conventional ducted System.

When choosing what SEER system to purchase, the biggest factor is: How long do you plan on staying in your home?

• If you plan on staying in your home for 5 years or longer, then a higher SEER system will pay for itself, over time, by saving you money on your electric bill.
• If you plan on moving out of your home in 1-4 years, then you will not be there long enough to recoup any of the added expense of purchasing a high SEER system, and so a standard efficiency system (14 SEER) makes more sense.

Brands of A/C and Heating Systems

There are many different brands of A/C and heating systems, some A/C Contractors offer only one brand, and others (like Allied A/C and Heating) offer most brands. The most important thing when comparing brands, is that you compare oranges to oranges. Magazines and websites like Consumer Reports generally calculate their rankings using the number of breakdowns that occur with each brand of A/C and heating systems annually. These resources are generally pretty reliable, and if you check a few different ones, you will start to see a handful of brands repeatedly showing up in the top 5 or 10.

Types of A/C and Heating Systems

The 3 most popular types of A/C and heating systems used in Florida are: Straight Cool, Heat Pump, and Gas Heat. These systems all cool the home the same way. The difference between them is how they heat the home.

Straight Cool- Straight cool systems are one of the oldest types of air conditioning systems. These systems use a heat strip to heat the home, and have the highest cost in electricity, when heating. As an example, these heat strips are similar, but bigger, than those used in electrical space heaters.

Heat Pump- Heat pump systems heat the home by essentially running the air conditioner in reverse, so instead of moving the heat outside the home, it brings the heat inside. It is more economical to move heat using a heat pump system, than it is to produce heat with heat strips. And even though a heat pump system does move less heat as the outside temperature drops, it is still more efficient than heat strips to run. Heat pump systems do use a heat strip as a supplement to the main heat, in case the outside temperature is too low, or you need to warm the house up quicker than normal. The heat strip also acts as emergency heat, in case the main heat isn’t working.

Gas Heat (Gas Furnace)- Gas heat systems have been around longer than air conditioners and are not very common in our area of Florida. This type of heat is mostly used in colder climates because the output temp remains the same even at very cold temperatures. A gas furnace produces heat by burning gas (natural gas, propane, etc.), the burning gas warms up one side of the heat exchanger (similar to an old style “radiator” heater), then air is blown across the opposite side of the heat exchanger and into the home. This type of heating uses less electricity than a heat strip, however, there is the added expense of gas cost to consider as well.

Major Components of an A/C and Heating System

All A/C and heating systems contain 6 major components: A Compressor, Condenser coil, Condenser fan, Evaporator coil, Evaporator fan, and a Heat Strip or Heat Exchanger. Also, these Systems contain various circuit boards, relays, safety switches, etc., that route the flow of electricity wherever it needs to go.

Compressor- The low hum that you hear when standing next to the A/C unit outside is the Compressor. The Compressor is the heart of the A/C system, it pumps refrigerant through the system, which allows heat to be moved inside or outside. Residential Compressors are completely sealed from the factory, so if something breaks inside it, it cannot be repaired, only replaced.

There are three different types of Compressors used in Residential A/C systems:

• One-Speed Compressors run at one speed only
• Dual Stage Compressors utilize two stages of cooling and heating. Most of the time the A/C system will run on its low stage, around 70% of total capacity. The System will run on high stage (100% of total capacity) only when necessary
• Variable-Speed Compressors “Ramp” up and down (20% – 100% of total capacity) depending on the situation, which maintains the efficiency of the system at all times. These are the most efficient type of Residential systems

Condenser Coil- The metal fins you can see on the outside A/C Unit are attached to a coil, this is called the Condenser Coil. Refrigerant is pumped through the coil, air is blown or drawn through the coil, and this is how the heat is released or absorbed outside.

Condenser Fan- The air you feel coming off the top of the outside A/C Unit is produced by the Condenser Fan. It consists of a Condenser Motor and a Condenser Blade and is responsible for blowing or drawing air through the Condenser Coil.

There are two different types of Condenser motors used in Residential A/C systems:

• Single-Speed Condenser motors run at one speed only
• Variable-Speed motors “Ramp” up and down depending on the load on the System and, as the name suggests, utilize more than one speed. These are the most efficient type of Condenser motor available today and are only used on high efficiency Systems

Evaporator Coil- The Evaporator Coil is completely enclosed and cannot be seen from outside of the unit. Refrigerant is pumped through the coil, air is blown or drawn through the coil, and this is how the heat is released or absorbed inside the home.

Evaporator Fan- The air you feel coming out of the vents inside the home is produced by the Evaporator Fan. It consists of an Evaporator (or Blower) Motor and an Evaporator Wheel (like a big, heavy duty hamster wheel) and is responsible for blowing or drawing air through the Evaporator Coil.

There are three different types of Evaporator motors used in Residential A/C systems:

• Single-Speed Evaporator motors may have more than one speed available, but only one speed can be utilized at a time (i.e. low – med – hi)
• Multi-Speed Evaporator motors also use only one speed at a time, however, they “Ramp Up” when they start, and “Ramp Down” when they turn off, making the A/C and Heating System overall more efficient
• Variable-Speed Evaporator motors “Ramp” up and down depending on the load on the System and, as the name suggests, utilize many speeds. These motors provide better Dehumidification than a Single-Speed Motor, and are the most efficient type of Evaporator motor available today

Heat Strip- A Heat Strip is basically a heavy-duty version of a toaster. It is a heavy gauge resistance element, shaped like a small, stretched out spring. When electricity is applied to the resistance element, it heats up. The Evaporator Fan then blows air across the Heat Strip to heat the home. Heat Strips are very good at producing heat, however, they are not very efficient on electricity.

Heat Exchanger- A Heat Exchanger is only used in a Gas Furnace. A gas furnace produces heat by burning gas (natural gas, propane, etc.), the burning gas warms up one side of the heat exchanger (similar to an old style “radiator” heater), then air is blown across the opposite side of the heat exchanger and into the home.

Configurations of A/C and Heating Systems

The type and layout of the home, as well as the current location of your unit(s), will generally dictate what configuration of A/C and heating system you will use.

Split-System- The Split-System is the most common type of A/C and Heating System. It consists of 2 main components: The Condensing Unit (or just Condenser) is the outside portion of this System, it contains the Compressor, Condenser Coil, Condenser Fan, and various electronics. Either an Air Handler or Furnace makes up the other half of this System, and can generally be found in the attic, garage, utility room, or closet. An Air Handler contains the Evaporator Coil, Evaporator Fan, Heat Strip, and various electronics. A Furnace contains the Evaporator Fan, Heat Exchanger, and various electronics, then a fully encased Evaporator Coil is mounted to the top of the Furnace.

Package Unit- The Package Unit is the second most common type of A/C and Heating System. Package Units are used mainly on Mobile Homes and for Commercial Applications. They contain all of the same components as a Split-System, but in one piece of equipment rather than two.

Mini-Split- Mini-Split A/C and Heating Systems are, as the name implies, a mini version of a Split-System, but the real advantage of a Mini-Split System is that there is no ductwork. The Air Handler portion of these systems are mounted on an inside wall and work very well for cooling/heating a single room. Also, some Mini-Split Systems are capable of running multiple Air Handlers (usually in separate rooms) using one Condenser. The most common uses of these systems are for finished garages, house add-ons, server rooms, etc., and are not practical for replacing conventional ducted Systems.

Window Unit- Window Units are the oldest type of A/C and Heating Units. Most of the original Units did not have heat, only Air Conditioning. However, the modern versions may be Heat Pumps and/or contain Heat Strips. These days, Window Units are mostly used for finished garages, porches, sheds, house add-ons, and Commercially in Motels/Hotels.

PTAC Unit- PTAC Unit stands for Package Terminal Air Conditioner, these are basically large Window Units, except they are mounted in a wall, rather than a window. They may be Straight Cool, Heat Pump, or have Heat Strips in them. The main advantages of a PTAC Unit versus a Window Unit, are that PTAC Units can service a much larger area and can be operated remotely using a regular Thermostat rather than the knobs on the machine itself. PTAC Units are used sometimes for single room residences, but are mainly used Commercially in Motels/Hotels.

Portable A/C Unit- Portable A/C Units are basically a rolling Package Unit. These Units are made to be used temporarily, they can be used alone for a single room, or to supplement a weakening A/C System until a replacement can be installed. The drawback of a Portable A/C Unit is that the hot air coming from the Condenser Coil must be vented outside the home using a window or sliding door, and this can sometimes be difficult or impractical.

Cool Caps & Leaf Guards

Cool Caps- Cool Caps have been around for many years, they basically look like a plastic garbage can lid, they are hinged on one side and are tethered to the Condenser Fan Grill on the other.

• Cool Caps are intended to keep leaves, etc. from piling up inside the Condenser, which can block the air flow across the Condenser Coil
• The downfall of a Cool Cap is that it relies on the Condenser Fan to lift it out of the way while the A/C system is running, this puts extra stress on, and shortens the life of, the Condenser Motor
• Cool Caps are basically obsolete, having been replaced by the superior, Leaf Guard
• We do not ever recommend using a Cool Cap on any A/C and heating system

Leaf Guards- Leaf Guards are made of a round, thin plastic mesh, and they come in a few different sizes, to accommodate any central A/C and heating system.

• Leaf Guards are intended to keep leaves, etc. from piling up inside the Condenser, which can block the air flow across the Condenser Coil
• Leaf Guards are fastened directly to the Condenser Fan grill and do not block the flow of air coming from the Condenser Fan
• Leaf Guards are only necessary if there are trees directly above your Condenser Fan

Dehumidification

Indoor comfort is achieved by controlling the temperature and the humidity inside the home. And, while indoor temperature is always important, indoor humidity control can be even more important, especially in high temp/high humidity climates, such as ours.

Humidity (for A/C purposes) is the amount of water vapor present in the air, inside your home. Humidity is measured in % of Relative Humidity (RH).

• Most people feel comfortable between 45% – 55% RH  ( @ 76°- 80°F )
• Mold and mildew are able to grow above 60% RH

Have you ever walked into a mall or big box store and your eyes and sinuses start to get dry?

• This is because these places run their A/C systems 24/7, and this tends to over-dehumidify these spaces (below 45% RH).  

Have you ever been in an Air-Conditioned home or business where it feels kind of cool but not comfortable? You look at the Thermostat and it says 75°F inside, so why doesn’t it feel comfortable?

• The reason it doesn’t feel comfortable is because of high humidity conditions (above 60% RH).

There are a many reasons why high humidity conditions can occur inside a home, here are a few major ones:

• Improper installation of the system
• Lack of maintenance and cleaning of the system
• Over-sizing of the system
• Old and/or leaking ductwork
• Old and/or leaking windows, doors, etc.

Dehumidistat

A Dehumidistat looks kind of like a Thermostat, with only one knob on it. However, it responds to humidity rather than temperature. Dehumidistats are only used in conjunction with a Thermostat and are mainly used by people in warm, humid climates who leave their homes vacant for extended periods of time. A Dehumidistat only allows the A/C System to run when the humidity in the home gets high enough to create moisture issues, regardless of the temperature inside the home. Because of this, the A/C system will only run enough to keep the humidity under control, avoiding mildew growth and resulting in lower electric bills when the home is vacant. Some modern Thermostats have dehumidification built into them, and can possibly serve the same purpose, depending on the conditions and situation.

Dehumidistat Settings for Unoccupied Home (longer than a week)

1. Set Dehumidistat between 50%-60% (mold can grow above 60%)
2. Set Thermostat to Cool and make sure the Fan is set to Auto (not On)
3. Set Thermostat temperature to 65°F (This will not cool your house to 65°F, this just gives the Dehumidistat complete control over the A/C System)

Your home is now protected from the effects of high humidity, also the System will be as efficient as possible while the home is vacant.

Dehumidistat Settings for an Occupied Home

1. Set Dehumidistat to On (completely clockwise)
2. Set Thermostat to Cool or Heat and make sure the Fan is set to Auto (not On)
3. Set Thermostat to desired temperature 

At these settings, the Dehumidistat cannot, and should not affect the operation of you’re A/C and Heating System, and the Thermostat now has complete control over your comfort.

Click here for our Printable Dehumidistat Instructions

Ductwork

Ductwork is what we use to circulate the air, that we Cool or Heat using the A/C and Heating System, around the home.

• Wherever there is a grille with a filter in your home, the air is being drawn in, towards the Air Handler, Furnace, or Package Unit
• The smaller grilles around the home, without filters, are where this air is blown back into the home
• Ductwork connects all these grilles to the System, and comes in many different sizes, types, and configurations

Metal Ductwork

In Residential homes today, metal ductwork is used mainly in homes with basements, where it is accessible and safe from heat and humidity. In Florida, where our ductwork is in the attic, exposed to our often brutal heat and humidity, metal ductwork and its insulation deteriorate and eventually leak. However, when central A/C and Heating first began, metal ductwork was the only ductwork.

Fiberglass and Flexible Ductwork

In Florida and places with similar climates, fiberglass ductboard and modern flexible ductwork are now the industry standard. Most of the old metal ductwork has been replaced with updated materials, but there are still some older metal ductwork systems out there. Modern duct systems are a mixture of ductboard boxes and flex duct.

The main advantages of these new materials are:

• Ductboard and flex duct have their insulation built into them
• Ductboard and flex duct do not deteriorate because of heat and humidity
• Ductboard and flex duct can be completely sealed, using duct mastic, which is not affected by heat and humidity
• Ductboard and flex duct are much lighter and easier to work with, and therefore take much less time to install or repair than metal ductwork

Mobile Home Flexible Ductwork

Mobile Homes use a special type of flex duct, because these ducts generally touch the ground. These ducts are exactly the same as regular flex duct, except that the outer layer is made of a heavy duty plastic to better resist moisture, etc.

Filters

Filters are a very important part of any A/C and Heating System. A large percentage of major repairs, as well as some health issues are due to improper filtration, often the result of neglecting to change filters regularly. Filters come in many different varieties, and trying to select the best filter for your home can seem daunting.

Let’s start with the two main purposes of an A/C and Heating System filter(s):

• To filter out airborne contaminants and prevent them from re-circulating back into the home
• To keep the ductwork and internal components of the air handler, furnace, or package unit from getting coated/clogged with dust, dirt, hair, etc., which will affect the efficiency and overall operation of the System

The next thing to consider when talking about filters is air flow, air flow is a critical factor in the efficiency and overall operation of your A/C and Heating System, and all filters affect the air flow of the System.

• If your A/C and Heating System and/or ductwork are improperly sized, installed, damaged, or if the System is old and struggling to maintain the set temperature; replacing a fiberglass filter with a pleated filter can decrease the efficiency and overall operation of the System by impeding the air flow through the System
• If your A/C and Heating System and ductwork are properly sized and installed, this loss of airflow will have a minimal effect on efficiency and operation
• Some filters are marked with an arrow because the air is supposed to flow through them in a certain direction, the arrow should always point into the grille or Air Handler/Furnace
• If you cannot find an arrow on the filter it probably doesn’t matter which way you put it in
• Not all filters are made to be used in a central A/C and Heating System

Types of Individual Filters

Foam- Foam filters are basically a very thin sponge. They are mostly used in Window Units and PTAC Systems and should never be used in a Central A/C and Heating System.

Metal Mesh- Metal Mesh filters are very thin weaved metal strips. They are mainly used in kitchen range hoods to catch grease from cooking and should never be used in a Central A/C and Heating System. (There is one exception to this, in some electronic air cleaners these types of filters are used as a Pre- or Post-filter)

Woven- Woven (or Hog Hair) filters are synthetic fibers woven into a ¾”- 1” thick mesh. These filters are only effective in filtering large particles. These can be used in central A/C and Heating Systems, but we do not recommend using them.

There were two reasons why these filters were used in the past:

• They can be cut to any size, for homes that have hard to find filter sizes

Today most homes use standard size filters, and the off sized filters can be found and ordered online.

• They are washable, for a while

Eventually, particles will build up in the middle of the mesh and will be unable to be washed out, at which time the entire filter will need to be replaced.

Fiberglass- Fiberglass filters (which no longer contain actual fiberglass) are synthetic fibers woven in a tight 1” thick mesh, the perimeter of these filters are usually made of cardboard. These filters have the least impact on air flow (with the exception of an Electronic Air Cleaner), and have, until recently, been the most common type of filter in use. They are the cheapest type of filter and do a mediocre job of filtering the air. However, these are not recommended if someone in the home suffers from breathing issues. These filters are rated for 30 days of use, maximum.

Pleated- Pleated filters are a thin tightly woven synthetic “cottony” material fixed in a 1” pleated formation and reinforced on one side, usually by metal wire or cardboard, and the perimeter of these filters are usually made of cardboard. These filters have more impact on air flow than the Fiberglass filters, but are quickly becoming the most popular, because of their superior filtering capabilities. We recommend using this type of filter, as long as there are no air flow issues with you’re A/C and Heating System If someone in the home has breathing issues, this is the first type of filter to consider. These filters are rated for up to 90 days of use.

Pleated filters come in an ever-growing selection of ratings, called a MERV rating (Minimum Efficiency Reporting Value), and the price generally increases with the MERV rating.

• The higher the MERV rating, the more efficient the filter is at trapping airborne particles
• The higher the MERV rating, the more the filter will impede the air flow

Types of Whole House Filters

Whole House filters are either mounted to or next to, the air handler or furnace. They are called “Whole House” because they filter the entire house with one filter instead of multiples. When using a Whole House filter, you should use 1” fiberglass filters in the individual grilles just to keep the dust out of the ductwork between the grille(s) and Whole House filter.

Media Filter- A Media Filter is a 3”- 5” Pleated Filter, and they come in an ever-growing selection of MERV ratings. It slides in and out of a metal casing that is either mounted to, or next to, the air handler or furnace. The main advantage of a Media Filter is that they are able to go longer than a 1” Pleated filter between changes due to the increased surface area used for filtering. These filters are usually rated for up to 90 – 180 days of use.

Electronic Air Cleaner- Electronic Air Cleaners are the best filtering, least air flow impeding, and most expensive type of filter. Electronic Air Cleaners, as the name suggests, run on electricity, and turn on automatically whenever air moves across them. There are several configurations, depending on the brand, but they usually consist of 1 or 2 – Pre-filters, 1 or 2 – 4” electronic filtering cells, and a Post-filter, which slide in and out of a metal casing that is either mounted to, or next to, the air handler or furnace. All the filters are washable or wipeable so there is nothing to replace regularly. The initial cost of these filters is high (usually $1,200 – $2,500, depending on its capabilities), but they do an excellent job of filtering the air and last for years.

How often to change/wash your filter

Fiberglass and 1” Pleated Filters can be found, in most standard sizes, at hardware stores, grocery stores, Wal-Mart, etc. If you have an odd size filter, or just for convenience, there are a multitude of websites to choose from, such as: Amazon, HomeDepot.com, Filtersfast, etc.

Media Filters should be bought exclusively online, A/C Contractors can buy them from HVAC Supply Houses, however, the price for these filters at an HVAC supply house is generally the same as it is online, for anybody. To order these online, you will probably need the Make, Model, and possibly size of the filter. Many times these filters are available in generic versions as well, that cost a little less.

How often you should change/wash your filter(s) depends on a few key factors:

Where is your filter(s) located?

• If your filter(s) is located in the wall close to the ground, they will get dirtier sooner than if your filter(s) is in the ceiling.
• If your filter(s) is close to an outside facing door they will be exposed to more dust and dirt.

Do you have pets?

• Pet hair, dander, etc. will cause filters to get dirtier sooner.

Do you have a Fiberglass or Pleated filter?

With any Fiberglass or Pleated filter, the best way to know if it’s time to change it is by looking at it.

• If you can tell it’s dirty by looking at it, then change it
• If you can’t tell by looking at it, then hold it and a brand new one up to the light, if more than 60% of the light is being blocked from showing through the old filter, it’s time to change it
• Once you have established how long it takes to get to 60% blocked, you know how often you should change it
• Whenever you change a filter you should write the date on the new one, in case you lose track of how long it has been in use

Do you have an Electrostatic or Electronic filter?

• If you have one of these filters you should have it checked when your regular A/C System maintenance is performed, and cleaned every six months to a year.

Warranties

The installing A/C Contractor should always register your new equipment Parts Warranty (always) and Extended Labor Warranty (if applicable) immediately after installation.

Most Parts warranties are non-transferrable, if they are transferrable, the length of coverage may be reduced upon transfer from one homeowner to the next.

Most, if not all, Labor Warranties are non-transferrable, and are only valid for the registered homeowner, at the registered address.

Any repairs that occur due to a lack of maintenance WILL NOT be covered by any Parts or Labor Warranty and will be the responsibility of the homeowner.

We strongly recommend a regular maintenance program on all new (and existing) A/C and Heating Systems to prevent any unwanted and/or unexpected repair charges.

Parts Warranties

Most brands of A/C and Heating Systems come with a Warranty on Parts from the manufacturer.

Parts Warranties cover PARTS ONLY, and DO NOT cover Labor of any kind.

If the System is not covered by a separate Labor Warranty, the homeowner will be responsible for Diagnosis and Labor charges.

Most System manufacturers offer:

• 10 year Parts Warranty on Primary and Secondary Homes, that are occupied by the owner
• 5 year Parts Warranty on Residential Rentals
• 1 Year Parts Warranty on Commercial Properties
• Parts Warranties do not include or apply to maintenance check-ups
• A/C and Heating Systems must have at least one maintenance check-up per year for the manufacturer’s warranty to remain valid
• Parts warranties do not apply to anything that did not come with the original equipment (i.e. drains, ductwork, filters, electrical feeds, piping, etc.)

Labor Warranties

Most brands of A/C and Heating Systems do not come with a Labor Warranty from the manufacturer.

Reputable A/C and Heating Contractors offer a 1 year Labor Warranty on new equipment installations, and in some situations more than a year.

• These Labor Warranties are covered exclusively by, and the sole responsibility of, the installing Contractor only
• Any Labor performed during this period (except in rare cases involving a factory defect or recall) will be at the Contractors expense

Extended Labor Warranties

Extended Labor Warranties are a supplemental coverage option available with the purchase of a new A/C and Heating System.

• Extended Warranties should be purchased and registered when the new System is installed
• Most Extended Warranties offer 10 years Warranty on Labor, supplemental to the manufacturers Parts Warranty
• Labor Warranties apply to any labor performed in the repair or replacement of warrantied parts
• Labor Warranties do not include or apply to maintenance check-ups
• A/C and Heating Systems must have at least one maintenance check-up per year for the Labor Warranty to remain valid
• Labor Warranties do not apply to anything that did not come with the original equipment (i.e. drains, ductwork, filters, electrical feeds, piping, etc.)

Refrigerants (Freon)

ALL Refrigerants are toxic to humans and should never be inhaled!

No one should ever attempt to interact with any Refrigerant without proper certification!

• “Freon” is actually a brand of Refrigerant made by Dupont. Dupont sells many different Refrigerants and they are all called “Freon”. However, Dupont is not the only company that makes and sells Refrigerants, and those companies all have their own brand names for their Refrigerants. What is important to remember is the ‘type’ of Refrigerant (R-22, R-410a, etc.)
• Each Refrigerant is paired with its own unique color, issued to it when it is patented, and used to identify it, no matter who manufactures or sells it (R-22 is light green, R-410a is pink, etc.)
• Refrigerants are the medium by which we move heat from one place to another, by using an A/C and Heating System. Heat is absorbed by the Refrigerant inside the home, and then released outside the home.
• There are many, many Refrigerants in use around the world, some of them are made of one chemical compound, and some of them are blends of different compounds or Refrigerants.
• Each Refrigerant changes from a liquid to a gas at a different temperature and pressure, this is one of the major factors that determines which Refrigerant will work for a certain application. For modern Residential A/C and Heating Systems we only have to worry about two, R-22 and R-410a.

R-22 (light green)- Refrigerant 22 is a single compound and the oldest type of refrigerant still used in Residential A/C and Heating Systems today. In the 1980s, the EPA (The U.S. Environmental Protection Agency) deemed that R-22 was not “Environmentally Friendly”, and began to inform equipment manufacturers that a change of Refrigerant was eminent. On Jan 1, 2010 the manufacturing of A/C and Heating Systems that use R-22 in the U.S. was banned, and R-410a became the new Refrigerant to be used in all Residential A/C and Heating Systems. The major downfall of this change for the Homeowner, is that R-22 and R-410a Systems are not compatible with each other. This means that if you have an R-22 Split-System and your Air Handler or Condenser needs to be replaced, you have to replace both pieces of equipment with R-410a equipment. According to the EPA, by Jan 1, 2020 all Residential A/C and Heating Systems must be using R-410a. Furthermore, since we are now getting R-22 from an ever-dwindling supply, the price has skyrocketed, and will continue to climb until there are no more R-22 Systems left in the U.S.

R-410a (pink)-  Refrigerant 410a is a blend of two different Refrigerants, it is “Environmentally Friendly”,  and is now the industry standard for Residential A/C and Heating Systems.

R-22 Substitutes / Drop-ins- Due to the climbing price of R-22, many “substitute” and “drop-in replacement” Refrigerants have appeared on the market. Most of them require modifications or updates to the System, but one Refrigerant is a “direct drop-in”, meaning that no modifications or updates are necessary to the System, RS-44b. This is the only R-22 replacement that we would recommend.

Thermostats

The Thermostat is the brain of your A/C and Heating System, it attempts to maintain a constant temperature in the home by controlling when the System turns on and off.

• Modern digital Thermostats are very accurate and reliable
• Thermostats are one of the least replaced parts of an A/C and Heating System
• If the Thermostat looks normal and acts normal, but the indoor temperature won’t catch up with the set temperature, then the issue is probably with your System, not the Thermostat
• If the digital display on your Thermostat is not lighting up, try changing the batteries if applicable, if this does not work, then the issue is probably with your System, not the Thermostat

There are two main kinds of Thermostat, because there are two main kinds of A/C and Heating system, Straight Cool and Heat Pump (see A/C and Heating Systems in FL).

All Thermostats have a “System” button or switch, this is how you set the System for Cool, Heat, etc.:

• If your Thermostat has the system options: Off – Cool – Heat, you probably have a Straight Cool A/C and Heating System
• If your Thermostat has the system options: Off – Cool – Heat – Em. Heat or Aux. Heat, you have a Heat Pump A/C and Heating System

All Thermostats have a “Fan” button or switch, there are three possible Fan options:

• Setting the Fan to “Auto” means that the indoor fan (Evaporator Fan) will only come on when the A/C and Heating System runs
• Setting the Fan to “On” means that the indoor fan (Evaporator Fan) will run continuously. This setting is usually only used when the windows are open and you want some air circulation through the home
• Some Thermostats have a “Circulation” setting for the indoor fan, as well as “Auto” and “On”. This is the same as the “On” setting, in most cases, and is mostly used in conjunction with Humidifiers.

All Thermostats display the indoor temperature, as well as the current temperature setting. When the A/C and Heating System is operating properly these two temperatures will be the same, mostly, if not all of the time.

When it comes to setting the temperature on the Thermostat, regardless of whether it is Cooling or Heating, there are only two things to remember:

• If you want it warmer, raise the temperature setting
• If you want it colder, lower the temperature setting

Types of Thermostats

Mercury- Mercury Thermostats were the standard for many years, but have become obsolete due to the introduction of digital Thermostats. The main problem with Mercury Thermostats is the loss of accuracy over time, but ultimately it was the toxicity of Mercury that pushed these off the market.

Coiled Spring- Coiled Spring Thermostats (or “Snap Action” Thermostats), as the name implies, use a coiled spring that expands and contracts due to temperature changes. They are cheap, inaccurate, unreliable, and rarely used on central A/C and Heating Systems.

Digital- Digital Thermostats (any Thermostat with a digital display) are the industry standard in modern A/C and Heating. They come in lots of different shapes and sizes, with lots of different options, but they all serve the same basic functions of operating the system. These Thermostats sense the indoor temperature very accurately, but not instantly. Modern Digital Thermostats take indoor temperature readings constantly and will not allow the displayed indoor temperature to change until a certain amount of time has passed, and the average temperature has remained steady. Basically, this means that your Thermostat will not tell you it is 75°F inside, until it is absolutely sure, that it is 75°F inside.

Other Types of Stats

Dehumidistat- A Dehumidistat looks kind of like a Thermostat, with only one knob on it. However, it responds to humidity rather than temperature. Dehumidistats are only used in conjunction with a Thermostat and are mainly used by people in warm, humid climates who leave their homes vacant for extended periods of time. A Dehumidistat only allows the A/C System to run when the humidity in the home gets high enough to create moisture issues, regardless of the temperature inside the home. Because of this, the A/C system will only run enough to keep the humidity under control, avoiding mildew growth and resulting in lower electric bills when the home is vacant. Some modern Thermostats have dehumidification built into them, and can possibly serve the same purpose, depending on the conditions and situation.

‘Click here for printable version of Dehumidistat instructions’

Humidistat- A Humidistat looks kind of like a Thermostat, with only one knob on it. However, it responds to humidity rather than temperature. Humidistats are only used in conjunction with a Thermostat and Humidifier, and are used by people in cold, dry climates to keep the home from becoming too dry inside. The Humidistat controls a Humidifier that raises the humidity in the home using bursts of a very fine mist of water, injected into the ductwork. Some modern Thermostats have humidification built into them, so there is no need for a separate Humidistat.

Digital Thermostat Options and Features

Non-Programmable- Non-Programmable Thermostats are the most common and simplest type of digital Thermostat. You set the temperature and the Thermostat will maintain that temperature until you physically change the setting.

Programmable- Programmable Thermostats allow you to schedule what temperatures you would like the system to maintain throughout the day. They usually have 2 or 4 scheduling options: Home/Away or Wake/Leave/Return/Sleep.

Automatic System Changeover- Some Digital Thermostats have an Automatic System Changeover setting, this setting must be turned on through the internal programming of the Thermostat (usually by the installing technician, but can be activated after setup). When this is turned on, you will find a new system setting option has appeared, so the “System” options are now: Cool, Off, Heat, Em. Heat, and Auto. When Auto is selected as the System option, you can input the Cooling temperature and the Heating temperature you want, and the Thermostat will automatically change from Cooling to Heating or Heating to Cooling. The only downfall of this setting is that the Thermostat will not allow the two temperature settings to be closer than 3°F, so if the two settings are 71°F (Heat) and 75°F (Cool), anytime the indoor temperature is 72°F – 74°F, the System will not run. The Thermostat uses this 3°F range to tell whether the indoor temperature is rising or falling, so then it knows whether to run the Heating or Cooling.

WIFI- If you have Wifi in your home you can use a Wifi enabled Thermostat. The main advantage of a Wifi Thermostat is that you can monitor and control the Thermostat using your Smartphone or Mobile devices. Some Themostats also have the option to display weather information gathered through the internet.

Dehumidification Loop- You may not realize it but whenever you’re A/C System is running, it is dehumidifying your home as well as lowering the temperature. Some Thermostats have a Dehumidification Loop built into them. This allows the Thermostat to run the A/C System to a lower temperature than what it is set for. By doing this the A/C System can dehumidify the home and increase overall comfort.

Humidifier Control- Some Thermostats have the capability to control a Humidifier (or a Control Board that controls a Humidifier). This is used mostly in cool, dry climates to keep the Humidity in the home from getting to low.

Outdoor Monitoring- Some high end Thermostats have the ability to monitor actual outside temperature and/or humidity using sensors that are mounted on the outside A/C unit. The actual temperature and/or humidity outside will then be displayed on your Thermostat. The sensors are purchased separately from, and must be compatible with, the Thermostat.

UV Lights

UV Lights (Ultra-Violet Lights)- UV Lights have become very popular to use in A/C and Heating Systems today. These devices use Ultra-Violet Light to sanitize the air in the home as it passes through the System. UV Lights and Air Purifiers will not reduce the amount of dust accumulation in the home. Excessive dust build-up is usually from infiltration through doors, windows, leaky ductwork, etc.

• UV lights fight the growth of mold and bacteria in the air and on any surface the light touches
• UV Lights must be mounted inside the Air Handler, Furnace, Package Unit or Ductwork, so that no light can be seen outside of the unit because UV Light can be harmful to human eyes
• The bulbs that these devices use last from 1-2 years, and then must be replaced

Air Purifiers- An Air Purifier is a UV Light that also uses Ion technology. So, in addition to the benefits of a UV Light these devices reduce odors, (excluding “Dirty Sock Syndrome”), air pollutants (dust, pollen, dander, etc.), VOC’s (Chemical Odors), smoke, mold, bacteria, and viruses.

• Air Purifiers naturally generate ionic oxidizers, using positive and negative ion technology, that actively seek out and purify pollutants in the air and on surfaces, and make even your existing air filter system better and more efficient than before
• Air Purifiers must be mounted inside the Air Handler, Furnace, or Package Unit or Ductwork, so that no light can be seen outside of the unit because UV Light can be harmful to human eyes
• The bulb/core that these devices use lasts from 1-2 years, and then must be replaced

Zone Systems

The term “Zone System” or “Zoned System” is used to describe an A/C and Heating System that uses a Zoned Ductwork System, rather than a normal Ductwork System.

• Zoned Systems use electric dampers in the ductwork to separate the home into zones
• Each Zone of the home has a Thermostat or Zone Sensor that sends a signal to the Zone Control Board (usually mounted near the Air Handler or Furnace)
• The Zone Control Board controls the A/C and Heating System as well as the Zone Dampers
• Zoned Systems should ONLY be used with multi-stage A/C and Heating Systems or when the Ductwork System has been adequately sized for a Zone System and has a proper Bypass Zone for releasing excess airflow

Zoned Systems were supposed to be a way, for larger and/or two-story homes, to cool or heat only the room(s) most commonly used, or when occupants want different temperatures in different rooms.

• Unfortunately, most Zoned Systems are improperly designed and/or installed, this stresses the A/C and Heating System, lowering its efficiency, life expectancy, and causing frequent repairs
• In most cases, Zoned Systems are unnecessary, if the Ductwork System is designed and installed properly, the air distribution will be balanced throughout the home

Zone Systems are usually marketed to homeowners as a way to save energy ($). They are told that it will drastically reduce power consumption –

This is true ONLY if the A/C and Heating System AND the Ductwork System are properly designed and installed (in 32 years in the industry we have not seen one yet) –

A properly designed and installed Zone System is much more costly than a standard non-zoned System for the initial installation –

We ONLY recommend using properly designed and installed Zone Systems IF it is absolutely necessary and will be beneficial to the homeowner in overcoming a specific issue

Duct Cleaning

There are companies that offer duct cleaning services that are legitimate, conscientious and do a good, thorough job. But, as with all industries, there are also companies that only want to separate you from your money. Beware of ads which depict horrific things inside your ductwork, and then advertise a “really low price” for removing them. The truth is, proper duct cleaning requires several very expensive, highly specialized pieces of equipment, plenty of labor, etc., so doing a proper cleaning for a “really low price” seems unlikely and suspicious. Also, if the ductwork is thoroughly cleaned, the A/C and heating system must also be thoroughly cleaned, adding more expense.

Allied does not currently offer duct cleaning services because we find that, most of the time, it is not yet cost-effective.

There are a few reasons why we feel this way, let’s start with the truth about dust in your ductwork. Every duct system over a few weeks old has some dust in it! The fact is, no matter what, a certain amount of dust is going to build-up inside your ducts. So, the first question is, How do I keep build-up to a minimum? And the answer is, with proper filtration and regular system maintenance. With proper filtration and regular system maintenance, a duct system could have 40 years of service before it’s dirty enough to consider cleaning or replacing it.

On the other hand, a poorly maintained system could be filthy within a matter of years, and possibly exacerbating, or even causing, health problems. So the next question is, How do I ensure that the dust that does build-up, is as harmless as possible? And the answer is, with proper filtration, regular system maintenance, and a UV Light and/or an Air Purifier. At present, this is the best formula to keep your Indoor Air Quality as high as possible, for as long as possible.

Mold

Mold is a very tricky subject, that we must address carefully. Strictly speaking, unless you can analyze possible mold samples, you don’t really know what that icky stuff in the corner is. Mold, mildew, algae, etc. thrive in warm, humid climates, and some people are affected by them more than others. Since your Air Conditioner is what cools, dehumidifies and filters the air in your home, it is critical that it is well-maintained and always working properly.

A poorly maintained A/C system is a breeding ground for mold and mildew, and if mold takes root in your system and ductwork, replacing them both may be the only option. And, if mold takes root in your home, depending on the severity, you could be looking at a complete home rehab, as well as replacing the A/C system and ductwork.

Using a UV Light or Air Purifier can fight the growth of new mold or mildew in your system and ductwork. However, even a well-maintained A/C system, utilizing proper filtration, and a UV Light or Air Purifier cannot kill or remove existing mold or mildew in the home. Specialized Contractors are necessary to properly remove mold from a home.