Contact/Relay -- Relays are electronically controlled switches that activate the various components of your HVAC system. They manage everything from the power going to the motor to automatic dampers, humidifiers, etc. Most of them are controlled by the thermostat. The most common failure for a relay is being stuck in the "open" position. Separated from its assigned contact point, it fails to complete the connection and send the message to whatever it was supposed to operate. This failure usually occurs from use over time. Each time a relay connects and sends its signal, the electrical arcing from point to point eventually causes wear and tear.
I believe a $3 [sic] pleated cotton filter is all that is ever needed to keep a system running top notch. A cleaning of the blower squirrel cage and of the evaporator [indoor] coil may be needed one time if fiberglass or no filters have been previously used. The return air grille [or grilles] need vacuumed off occasionally, as they are upstream from the filter. The $3 filter should be changed every 3 months [rule of thumb]....and most of them have a little white square on the cardboard frame to write install date.....and the arrow should point into the duct [if at filter grille]....or towards the furnace [if in ductwork slot]...or towards the blower [if in blower compartment]. My two cents.....
The Environmental Protection Agency says that “duct cleaning services typically – but not always – range in cost from $450 to $1000 per heating and cooling system, depending on the services offered, the size of the system to be cleaned, system accessibility, climactic region, and level of contamination” and type of duct material. Consumers should beware of air duct cleaning companies that making sweeping claims about the health benefits of duct cleaning – such claims are unsubstantiated. Consumers should also beware of “blow-and-go” air duct cleaning companies. These companies often charge a nominal fee and do a poor job of cleaning the heating and cooling system. These companies may also persuade the consumer into unneeded services with and/or without their permission. (If you have knowledge of a practicing “blow-and-go” air duct cleaner, contact your local Better Business Bureau to report the company, and your local, federal, and state elected officials to demand legislation.)

Your HVAC unit and air ducts deliver heated or cooled air throughout your home year-in and year-out. The air your HVAC unit produces travels through your ductwork and heats or cools your home via the air vents in each room. The dust and other particles in your home’s air are known as particulate matter, which the EPA defines as "a complex mixture of extremely small particles and liquid droplets." The EPA also notes that "particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles." Having clean air ducts means fewer of these particles moving through your home. If you remove your furnace filter and hold it up to the light, you can probably see several hundred of these minuscule particles floating in the air. 
Asking how much an HVAC installation costs is kind of like asking, “how much does a new car cost?”  Well, are you buying a Porsche or a Honda? Is it a 911 or just a Boxster, and are you going to get the leather seats? Likewise, are you going to get a Carrier or a Goodman air conditioner? Does the ductwork need to be replaced? These are all questions that will affect your HVAC installation cost, so let’s take a closer look.
R-22 Freon is being phased out & isn't readily available. So the service company may only purchase as needed and the lack of availability would make their cost high. But, as long as they can get it, whatever the cost, unfortunately, is less expensive than replacing the A/C. Which will be the case eventually since it's no longer manufactured or sooner as in my case with a not so old a/c that sprang a leak, that would have been just a repair, but since it uses R-22 the whole unit has to be upgraded(replaced).  

If you’re purchasing from a big-box store, you can expect to pay approximately $120-$1,000 for a window unit. Window units are appealing for their quick setup and relatively low cost, but they can use more energy over time than central air and only cool the room in which they’re installed. The price will vary depending on the type of air conditioner you buy and its cooling capacity. Window units, which require minimal installation, are one of the most affordable options on the market. Portable air conditioners don’t have the cooling power of a window unit, but they do have the perk of being transportable from room to room. Expect to pay between $225 and $800 for a portable air conditioner, on average. The cost of an air conditioning system with coils, condenser and line (not including installation or ductwork) can range from approximately $2,000 to $4,000 or more. If you don’t have (and don’t want to put in) ducts, a ductless mini-split air conditioner is a good option, although pricey up front. Pricing can range from $650 to $4,250 per unit on average; you’ll need one unit for each room in which you want temperature control.
The number of years an HVAC system lasts depend on the type and brand of components that make up your system. The lifespan of an air conditioner averages between 15 and 20 years. The life expectancy of a tankless water heater is approximately 20 years, while a storage water heater is closer to 10-15 years. Ducts may need replacing within 10-15 years. Your equipment will have a longer life if you have regular tuneups and maintenance to keep everything in good working order. If you’re having repair problems and your HVAC system is over 10 years old, it’s a good time to consider the costs and benefits of repairing vs. replacing. provides the following tips to help you decide whether to repair or replace:

They work less jobs, thus increasing profits – think about it…if they got only half of the jobs, then they only pay half of the money required to pay employees, expenses, etc., but still have the same amount of net profit. In fact, if you do the math, they actually make more profit that their competitors do…twice as much, once you factor in their savings form only doing half of the jobs at the same amount of profit (Total Revenue – (half the normal expenses) = twice the profit). In other words, they save money by doing half of the jobs as others, for the same profit, thus increasing their overall profits.
While you consider having your air ducts cleaned, it is a good idea to take a look at your dryer vent. If your dryer vent is clogged, you could be losing energy efficiency. Worse yet, you could be increasing the risk of a house fire. Having your dryer vent professionally cared for costs about $130 on average, and could save you a bit of money and a lot of headaches in the future. For more information on the benefits and cost of having your dryer vent cleaned, take a look at our comprehensive cost guide.

On the other hand, if a service provider fails to follow proper duct cleaning procedures, duct cleaning can cause indoor air problems. For example, an inadequate vacuum collection system can release more dust, dirt and other contaminants than if you had left the ducts alone. A careless or inadequately trained service provider can damage your ducts or heating and cooling system, possibly increasing your heating and air conditioning costs or forcing you to undertake difficult and costly repairs or replacements.
Before you choose any duct cleaning service provider, interview as many service providers as you can. Ensure that the service provider is certified by the National Air Duct Cleaners Association or NADCA. Make sure that they hold a good standing in the Better Business Bureau and have all the necessary certifications and license. Be clear about their terms of service. Make sure they have the right equipment to do the job. It is best to go for a company that has been tried and tested successfully by any of your acquaintances or opt for a service provider that has been in the business for quite some time.
An air conditioner's compressor contains a refrigerant. As it works, it sends this refrigerant through the system. As warm air blows across the coil that carries this refrigerant, the heat transfers to the refrigerant (cool always absorbs warm). A fan moves the cooled air through the ducting and out of vents that lead into the rooms of your house. The refrigerant returns to the compressor where the absorbed heat is moved outside. The refrigerant is then sent through the coil once again to continue the cycle.
These factors are included in a "Manual J" calculation. Contractors who make these calculations before recommending a size can take a couple of hours collecting the information and making the calculation. If your contractor doesn't do it, there are services that will do it for around $99. If you're feeling particularly on the ball, there are also free online calculators.
The Chartered Institution of Building Services Engineers is a body that covers the essential Service (systems architecture) that allow buildings to operate. It includes the electrotechnical, heating, ventilating, air conditioning, refrigeration and plumbing industries. To train as a building services engineer, the academic requirements are GCSEs (A-C) / Standard Grades (1-3) in Maths and Science, which are important in measurements, planning and theory. Employers will often want a degree in a branch of engineering, such as building environment engineering, electrical engineering or mechanical engineering. To become a full member of CIBSE, and so also to be registered by the Engineering Council UK as a chartered engineer, engineers must also attain an Honours Degree and a master's degree in a relevant engineering subject.

Wiring up the thermostat is usually pretty straightforward if an old one is being replaced. If a thermostat is being put in where one had never been before, that could involve running new wiring. The placement of the thermostat is also important so that its sensors can get an accurate reading of the temperature. A thermostat that is blocked by a bookcase or other large furniture will not get a good reading and will not perform efficiently.
If no one in your household suffers from allergies or unexplained symptoms or illnesses and if, after a visual inspection of the inside of the ducts, you see no indication that your air ducts are contaminated with large deposits of dust or mold (no musty odor or visible mold growth), having your air ducts cleaned is probably unnecessary. It is normal for the return registers to get dusty as dust-laden air is pulled through the grate. This does not indicate that your air ducts are contaminated with heavy deposits of dust or debris; the registers can be easily vacuumed or removed and cleaned.
Excalibur Water Systems helps solve the water challenges around the globe with water solutions for any possible water concerns in: water hardness, filtration of any contaminant, bacteria removal and high purity water needs and also comes with a warranty of up to 20 years at no extra cost. The best warranty for the water treatment equipment industry.
Installation: The old furnace is disconnected from the ductwork plenum, exhaust flue, gas and electrical hookups. In most cases, a new plenum must be made onsite or ordered from a local sheet metal fabricator. A new vent might be required too. The furnace is set and reconnected. Adjustments to the blower fan speed and burner are made to optimize furnace performance for your home and climate.

An example of a geothermal heat pump that uses a body of water as the heat sink, is the system used by the Trump International Hotel and Tower in Chicago, Illinois. This building is situated on the Chicago River, and uses cold river water by pumping it into a recirculating cooling system, where heat exchangers transfer heat from the building into the water, and then the now-warmed water is pumped back into the Chicago River.[24]
Had our ducts cleaned late April, 2016. Sodium Chlorite was sprayed into ducts after cleaning. Ever since, we have been bothered with eye and nasal passage irritation because of a “chemical” and “musty” odor. This odor is present whether or not a/c is on.) We are told the sodium chlorite (“EnviroCon, manufactured by Bio-Cide International) is used in hospital and nursing home settings and is not hazardous to health. The air duct company’s suggestion is that they come out and spray even more sodium chlorite…we absolutely don’t want this done! Have had various other recommendations about what we need to have done to remedy our problem. We will be unable to stay in our home if a resolution cannot be found. We’d be willing to replace the ductwork if necessary. (One professional suggested that the cleaning may have “knocked something loose” inside the ductwork and that is the source of the irritant.) This home was built in 1920…no idea when the present ductwork was installed. Any suggestions would be appreciated.
First of all, I think it is great that there are many companies out there who look out for the customer and protect their interest. Secondly, I think it is also important that customers consider having their HVAC systems checked thoroughly before moving into a new home. I have heard a couple of horror stories where previous owners have not had the best housekeeping skills. Even when the appearance of the home seems it has been well kept, keep in mind that surface clean only goes so far. You can never tell what lies underneath.
Indoor Coil -- The indoor coil is a heat transfer device. It absorbs the heat from the inside of the house and passes it on to the refrigerant and is pumped outside. Dust that builds up on the coil can hamper its ability to absorb heat. High heat transference coils use very thin metal. Airborne chemicals can cause corrosion which leads to leaks. The constant vibration of the compressor can also cause solder joints to weaken and leak. An indoor coil may operate for weeks with a tiny leak, and you may not notice the loss in performance right away. As soon as a leak is made known, it should be replaced or repaired immediately.
An air conditioning system's SEER is especially important if you live in a climate that changes temperature dramatically. The SEER is determined by the cooling output during the winter divided by its electric input during the winter. The higher the rating, the more efficient it will be. In January of 2006, the U.S. put standards in place for cooling units which are still in effect today. They must have a minimum SEER of 13. So, if you live in a home with a system installed before the new standards went into effect, consider having it replaced. SEER 13 units increase home efficiency by 30 percent.
You may be familiar with air ducts that are constructed of sheet metal. However, many modern residential air duct systems are constructed of fiber glass duct board or sheet metal ducts that are lined on the inside with fiber glass duct liner. Since the early 1970's, a significant increase in the use of flexible duct, which generally is internally lined with plastic or some other type of material, has occurred.
Asbestos removal tip.  Don’t trust any HVAC installation company that says that they will remove asbestos for you. They will do either one of two things: remove it and do a horrible job because they don’t know how (an illegal act in California, finable by up to $250,000), or they will say they did and never actually do it, which is dangerous to your health. Any HVAC contractor worth their weight will know not to touch it. Call an asbestos abatement company – it should cost around $500-$1,000, and your HVAC installation company will come in right after them and do the installation to decrease cost and inconvenience.
Replacing a capacitor is easy. Just take a photo of the wires before disconnecting anything (you may need a reference later on). Then discharge the stored energy in the old capacitor (Photo 4). Use needle-nose pliers to pluck one wire at a time from the old capacitor and snap it onto the corresponding tab of the new capacitor. The female crimp connectors should snap tightly onto the capacitor tabs. Wiggle each connector to see if it's tight. If it's not, remove the connector and bend the rounded edges of it so it makes a tighter fit on the tab. When you've swapped all the wires, secure the new capacitor (Photo 5).