Our HVAC Ductwork Installation Cost Guide is the most comprehensive guide of its type. It fully explains the purpose of ductwork and all your options. Pricing is included for all duct types and plenums/drops too. Material and installation costs are listed. Ductwork cost varies greatly by the size and type of duct plus the complexity of the installation, but you can expect to pay $10.20 to $17.25 per linear foot installed.

The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and the emission of carbon monoxide, nitrogen oxides, formaldehyde, volatile organic compounds, and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects.[14]

yes get a good company and pay the price, I found so much dust and dirt and wood and paint chips and bugs and even bottle caps in my ductwork. I hired a major plumbing company who cleaned ductwork and i will say they did an excellent job cleaning my vent. they did miss one point in my ductwork because i still started to see dust all over my furniture and i realized that my retunduct work that was connected with a piece of sheet metal beam which was 16" across , the contractor that built my condo used a 16" wide sheet of sheet metal to connect the vent system to my return for the air to return back into my condo. The contractor should have built a 8" x16" square duct by 6 feet long to connect my intake to my return instead of using a sheet of sheet metal 16" wide by using two 3' sections by 16 inches wide. That was a shor cut which caused a major problem fir me.

Be careful with HVAC change-outs.  Change-outs are only about 15-20% of the HVAC installation industry. Decrease HVAC installation cost by investing in new ductwork now if needed. Your ducts wear out too, and make sure that your ducts are in fantastic shape if you do this. Many contractors push this because it’s easy and cheap for them, with good pay-off. Do your research and replace them if you need to in order to avoid doing it later, as well as avoid potential health hazards from using old, broken ductwork.

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.
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.
I need a complete system replacement , before I was trying to get an evaporator coil replaced , of course the price is between $2200 an $2800 , then get told it probably will over tax my ac unit within months , so now and like everyone else what do you buy 14 ,15 16 17 seer units ,price and how do we know its reasonable  why can't there be '" a estimated price ,in the ball park, a range of prices ,so we can at least go from their .....  Now it's from 7500 to 15000. Frustrating  from the start so everybody good LUCK.   Draw a # from the hat    Unregulated  and who do you BELIEVE, just like on NCIS go with your gut feelin   
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.
"Customer service was great, and the price was in-line with other places, and fast service. We had a whole replacement of the outside and inside. I would have liked to see a better install for the furnace and new thermostat - the new thermostat should have gone where the old one was, and even tho the new furnace was a tight fit, they didn't offer to come back and repair the case molding, or give me a discount on the damage done, and I believe they should have put a disconnect box on the outside of the home, to make it easier for any future repairs needed. Other than that, am very happy with the cooling and heating!"