Bigger is not necessarily better when it comes to HVAC systems, and smaller isn't always more efficient. If you have too small of a system, your system will be running constantly as it tries to keep up with the temperature. If you have too large of a system, it won't run long enough to keep up with the humidity. In order to handle both temperature and humidity efficiently, an HVAC system should run for around 30 minutes at a time. If your system is staying on too long or shutting off after only around 10 minutes, you are not getting efficient performance.
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.
So, the total price to a contractor for this project is $7,195.77 (Carrier is expensive), which we’ll use to calculate a fair HVAC installation cost. As I said, we typically use 40% in the industry to cover our own personal profit, as well as our insurance and other expenses. Let’s take a look at page three of a Final Report from our own online HVAC calculator, the HVAC Design & Consultation Program.
PickHVAC Tips: First, see the PickHVAC tip above about sizing a central air conditioner. It applies to heat pumps just as much. Secondly, Even if the line set for the new heat pump is the correct size, we recommend replacing the set or at least the fittings. Old lines and fittings are a major source of leaks. When refrigerant leaks out, the heat pump efficiency suffers. Eventually, the unit stops providing heating and air conditioning, and it might break down.
CIBSE publishes several guides to HVAC design relevant to the UK market, and also the Republic of Ireland, Australia, New Zealand and Hong Kong. These guides include various recommended design criteria and standards, some of which are cited within the UK building regulations, and therefore form a legislative requirement for major building services works. The main guides are:
The three major functions of heating, ventilation, and air conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can be used in both domestic and commercial environments. HVAC systems can provide ventilation, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces is known as room air distribution.[3]
SEER is useful for comparing one model to another much in the same way that a car's calculate MPG is useful. It's not an accurate prediction of exactly how efficient the system is, but it can tell you which one is more efficient. Also, since SEER is based on a "cooling season", what region you live in will determine how long or short your cooling season is.
AC air handler squealing or grinding noises. Though most air handlers have direct-drive motors, some older units may be belt-driven. Squealing sounds from a belt-drive air handler generally occur when the belt that connects the motor to the blower slips. In most cases, the belt is improperly aligned or worn and needs replacement. Follow the instructions above under Air Conditioner Not Blowing Air and refer to your owner’s manual.
Important Tip: Don’t just pay attention to the high-end of the price range! – which is what I know you are all looking at, but also look at the low range. If a contractor is cheaper than this, ask “why?” Usually it is because they don’t have liability insurance, workman’s compensation insurance, are unlicensed, all of the above, or worst yet, they don’t use HVAC technicians. You are spending a lot of money.  Make sure that they are licensed (In California, check here at CSLB License Checker) and insured.
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Many homes have a forced-air HVAC system. Both the heating and the central air conditioning units share a ductwork system where they either push in or pull out warm or cooled air. There are also heating and cooling systems that don’t require ductwork — such as ductless mini-splits — but work on the same principles of heat exchange. The national average to hire an HVAC specialist is $2,920-$3,670, with costs varying depending on the work you need done and the equipment you are installing.

HVAC services is our go to contractor when it comes to our HVAC needs. Back in 2013, we were dealt some unforeseeable home projects, as our  HVAC was failing and needed to replace the whole system, e.g. Furnace, Blower, A/C, Condenser, Vents, etc... We reached out to a few HVAC companies (Contra Costa Heating and Air, EP builders, High Performance Heating and Air) so we could compare the bids for the job. We have had some issues with past contractors and after thoroughly screening a few of the above mentioned HVAC contractors, we awarded the bid to HVAC services because of their superior customer service and very reasonable pricing.

When central air conditioning service fails during a heat spell, you may have to wait days for an HVAC repair technician or an ac contractor to show up, and you'll probably pay at least several hundred for the repair. But if you're comfortable working around electricity and are willing to spend about $50 on parts, you can probably repair your air conditioning service yourself in about two hours and save about $225 on parts markup and labor.
My Carrier furnace occasionally (one-two times a day) does not start. It shows error code 15 ("BLOWER MOTOR LOCKOUT -This status code indicates the blower failed to reach 250 RPM or the blower failed to communicate to the variable speed furnace control within 30 seconds after being turned ON in two successive heating cycles."). However, when I turn off and on the furnace power switch it starts and runs fine for a while. Sometimes it runs fine all day, but does not start only once in the evening or in the night. It is 13 years old I was thinking to replace whole thing if repair cost is too high. But I am not ready to pay $10,000. 

Installing a split system may involve making modifications to the house itself for the necessary lines to be run. The heat exchangers are also more prone to picking up debris and must be cleaned on a regular basis. While they come with protective screens over the fan, care must still be taken to ensure that nothing gets in, especially in a home with children.
HRV/ERV Ventilators: These whole-house ventilators exchange air. They are ideal for homes with what is called a “tight envelope,” homes where house wrap has been applied and airgaps in the attic, around windows, doors and outlets have been sealed. Air in these homes becomes stale and polluted, so exchanging the air is important to IAQ. Heat recovery ventilators (HRV) are designed for cold climates. Energy recovery ventilators (ERV) are best for warm climates.  Your cost for an installed HRV or ERV will range from about $2,000 to more than $5,000 based on its capacity and features.
HVAC System Quality Installation Contractor Checklist -- This checklist identifies all of the steps the contractor has taken for the Energy Star Certification and identifies what work the contractor has done. If the system is later modified, this checklist can help identify what was done to proper Energy Star specifications and what was added later that may not meet the requirements.
Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through radiation, convection, or conduction. Refrigeration conduction media such as water, air, ice, and chemicals are referred to as refrigerants. A refrigerant is employed either in a heat pump system in which a compressor is used to drive thermodynamic refrigeration cycle, or in a free cooling system which uses pumps to circulate a cool refrigerant (typically water or a glycol mix).
Duct system installation and repairs affect HVAC installation cost. If you’re installing a new forced air heating or cooling system, your home must have ductwork – if you don’t have ducts installed, a new duct system will need to be designed and installed. Your existing duct system may require air sealing to eliminate air loss, helping your new heating and cooling system operate efficiently.
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]
PickHVAC Tips: Installing the right size central air conditioner is extremely important. Have a load calculation done to ensure proper sizing. ACs that are too big aren’t as energy-efficient as they should be, and they cycle on and off too much. This creates over-cooling and temperature imbalance. Units that are too small run constantly in very hot weather and can’t keep your home cool. When an air conditioner is properly sized, it runs at optimal efficiency and indoor comfort.

I even asked if this is something they don't do, as in services on a Saturday night.  I was told by the receptionist that they do and I would just be ok calling another company if they is not  part of their services. They again assured me someone WILL call me in 10 mins.  Well, unless their definition of 10 mins is never, then they got it wrong as I am still waiting to be called 5 days later.


My point is that the brand of equipment you choose is going to affect your HVAC installation cost greatly. People often call us for an air conditioning installation job and say, “I would like to install Carrier equipment.” Now, if you are a future client of ours, I’ll have to warn you – I can be a bit of a smart-ass. Why can’t work be fun? Besides…I was in the Navy for 11 years, what do you expect. 
The cost to replace a central air conditioner is about $5,000. However, this price varies depending on the size of your home and the difficulty of the project. It can cost as much as $12,500 to replace an AC unit. The labor required to remove and dispose of the old system adds to the price. The size of your home, brand of AC unit and ductwork complexity can all raise the cost as well.
The most recognized standards for HVAC design are based on ASHRAE data. The most general of four volumes of the ASHRAE Handbook is Fundamentals; it includes heating and cooling calculations. Each volume of the ASHRAE Handbook is updated every four years. The design professional must consult ASHRAE data for the standards of design and care as the typical building codes provide little to no information on HVAC design practices; codes such as the UMC and IMC do include much detail on installation requirements, however. Other useful reference materials include items from SMACNA, ACGIH, and technical trade journals.

The performance of vapor compression refrigeration cycles[26] is limited by thermodynamics. These air conditioning and heat pump devices move heat rather than convert it from one form to another, so thermal efficiencies do not appropriately describe the performance of these devices. The Coefficient-of-Performance (COP) measures performance, but this dimensionless measure has not been adopted. Instead, the Energy Efficiency Ratio (EER) has traditionally been used to characterize the performance of many HVAC systems. EER is the Energy Efficiency Ratio based on a 35 °C (95 °F) outdoor temperature. To more accurately describe the performance of air conditioning equipment over a typical cooling season a modified version of the EER, the Seasonal Energy Efficiency Ratio (SEER), or in Europe the ESEER, is used. SEER ratings are based on seasonal temperature averages instead of a constant 35 °C (95 °F) outdoor temperature. The current industry minimum SEER rating is 14 SEER.[27][dead link]
American design standards are legislated in the Uniform Mechanical Code or International Mechanical Code. In certain states, counties, or cities, either of these codes may be adopted and amended via various legislative processes. These codes are updated and published by the International Association of Plumbing and Mechanical Officials (IAPMO) or the International Code Council (ICC) respectively, on a 3-year code development cycle. Typically, local building permit departments are charged with enforcement of these standards on private and certain public properties.
When central air conditioning service fails during a heat spell, you may have to wait days for an HVAC repair technician or an ac contractor to show up, and you'll probably pay at least several hundred for the repair. But if you're comfortable working around electricity and are willing to spend about $50 on parts, you can probably repair your air conditioning service yourself in about two hours and save about $225 on parts markup and labor.
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