The HVAC installation costs below are based on residential installations only, and are priced for a single unit. Two units should be about twice the price. “Tim, shouldn’t there be a discount?” If people start giving you discounts, they are probably charging you too much to begin with.  That’s our philosophy anyway. Twice the parts and time should be twice the price from a fair contractor. The prices listed include component parts (with warranty), labor, and all materials for a complete HVAC installation.
Pro HVAC company Southern Comfort Mechanical says on its blog, “If there’s mold growth inside the handler due to excess moisture, algae in the condenser drain line or a dirty evaporator coil, it can negatively impact your AC unit’s efficiency. The filters inside may also build up excess dirt and become clogged, which will also make your AC [or heat pump] waste energy trying to sustain the cool climate inside your home.” These issues are easy to solve. They don’t require replacing the air handler.
Consider what kind of heating and cooling system you want installed for the square footage of your home. Do you want a full system with a thermostat or a specific machine for the summer like a swamp cooler? Do you need a new furnace just for the winter? For any of these projects, the cost will vary depending on the quality, style and machine size you choose. If you have a tight budget, think of going smaller and upgrading over time. For example, if you can't afford to convert your entire home to solar power, you may want to consider only utilizing it to heat your water. Some other types of heating systems are:
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.
This is where i found where the major problem was for the dust problem in my home. I took down the sheet metal that was 16" wide down by taking the screws out that keep it attached and when i took it down i, could not beleive the amountbof dust that was up there, inhad to put on breathing nasks to actually scoop out all the cust with my hads and then i used my shop vac then bleached everything, i would say that i filled up a 5 gallon maybe more not counting all the dust that was attached to the side of the beams that was all wood , because the contractor did not actually build a 16" wide return all out of metal , butvinstead used the sheet metal plate as a short cut to make a suare box using my beams in my basement to make a suare box. I was told contractors do that often and i feel that should be outlawed because it caused my sinus and allery problems,nwhich almost caused me to die. so everyone should make sure their ductwork was made properly. Yes seal it . Cover all openings. So it was not the contractors fault that my vents still had dust, in them, he was afraid tomgetvon top of my pool table to try to get iside the short cut ductwork with the 16" wide sheet metal. To everyone, make sure you clean your vent system. And make sure you could see it visually like i did , neither i or the contractor had no clue the problem was right above my pool table because of the make shift ductwork. The contactor shoul have made a squrae duct like the rest instead of using my beams as a short cut. That could be whyba lot of people start to have major allergy problems and maybe even coverall holes to prevent dust to be taken in and all bugs etc. then make sure you clean your ductwork as you see reasonable, they say every 5 years , but i say evry 2 to 3 years, but you can do it yoursely.. You need a good air hose and suction vacum like a shop vac, do a little research. I invented something a while back like 18 to 20 years ago , and now it is on the market to help homeowners such as ourselves with this dust problem. I cannont say anymore because i have to make sure that it was not my research and idea that solved my problem and for all the others that are using what i invented ..there was nothing on the patent search that i hired an invention company to do, back then. Once yor vents are cleaned properly younwill be very happybif you are an allery sufferer. Stop the children for throwing things into the ductwork and sweeping things into the ductwork, keeping your vent system is clean once youbclean it right the first time, just maintain it , you dhould keepmthe hvac system clean such as coils etc it truly helps,people vome into my condo and they cannont beleive how cold it igets and how my system works so well. it is because i have my whole duct system sealed outsid with the duct sealant and my coils i vleaned my self and take the time that the furnase fan is cleaned because that could have a lot of major dust attached to it, mine had a lot of caked on dust it was like hard dirt. Yxounwill save on allergy bills nasal sprays, i wish I could say more because incould say something to really keep your whole duct system clean for years once you do a first good cleaning of intake and return vents. until i email one of the major companies to see where they got my idea from. Intrulybhope it was not from the invention company i hired years ago who did the patent search for my idea. I becam

The EPA is so far behind on useful knowledge because of the lack of funding so don't be mislead. The Hvac old timers were left at the dock so to speak and missed out on the IAQ movement. The ones that are savvy and up to date on the information do Air Duct Cleaning, even tho that will lead to a few less service calls its the right thing to do for their customer. Please take a look into a return duct that has never been cleaned, I dare anyone to say it does not need to be cleaned.

In modern buildings, the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity and type of system needed and then design the system, selecting the appropriate refrigerant and various components needed. For larger buildings, building service designers, mechanical engineers, or building services engineers analyze, design, and specify the HVAC systems. Specialty mechanical contractors then fabricate and commission the systems. Building permits and code-compliance inspections of the installations are normally required for all sizes of building.
If you believe that the AC's not working or you're getting little or no cold air, check these three things first. Make sure all the registers in the house are wide open. Then be sure the furnace filter is clean. Then go outside and clean off the condenser coils (Photo 2). If several registers were closed or the filter was clogged, the reduced airflow could have caused the evaporator coil to ice up and stop cooling your home. If you've changed the filter and opened all the registers and you're still not getting airflow at the registers, deice the A-coil. Move the thermostat mode switch from “Cooling” to “Off” and move the fan switch from “Auto” to “On.” Let the blower run for at least 30 minutes or until there's good airflow at the registers. Then turn the AC back on to test it. If it works for the next 12 hours, you've solved the problem.