A little simple math can help determine the size system you need. A rule of thumb is 20 BTUs per square foot. So, a 500 square foot room would need 10,000 BTUs to cool or warm it efficiently. This assumes that you live in a temperate region and have adequate insulation with no energy loss. In the real world, all units have some degree of energy loss. This is reflected in an HVAC system's SEER rating for cooling and AFUE rating for heating.
Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and the architecture permits. In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (stack effect), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate.
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.
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.
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.
Unfortunately, manufacturers and contractors don’t publish this information…it’s a secret. Why? Who knows…but we have access to a full contractor pricing database of 1,000’s of different units in our online HVAC installation cost calculator, so let’s choose one for our example calculation. We’ll go with Carrier equipment, since our readers always bother us about them (despite us telling them that they are overpriced):
Is there a such thing as a PQ-15 valve? No…but how do we know? And oh, by the way, there are only two types of line-sets: 3/4 inch, and 7/8 inch. All modern equipment runs on a 7/8 inch line-set, so the only time they’ll have to change something is if you have antiquated 3/4 inch line-set from the 60’s or 70’s. I’m digressing though…the point is that they can easily prey on uninformed consumers…like you, baby bird! Don’t worry though…you’ll be flying by the end of this article.
If the condenser coils are clogged, the compressor can overheat and shut down. You'll experience intermittent periods of minimal cooling, followed by no cooling. Even if you're “sure” the condenser coils are clean, clean them again. Turn off the power. Flip the air conditioning service and furnace circuit breakers in your main electrical panel to the “Off” position. Next, turn off the power switch right at the furnace or air handler. Then yank the disconnect block (Photo 1) and clean the condenser coils (Photo 2). If the air conditioning service still doesn't work properly after you've cleaned the condenser coils, installed a new filter and opened all the supply vents, proceed with the following repairs. Your AC won't work fully unless you do this.
Yes everyone should get all their ductwork cleaned, because it does help, incame down with major allergies and had serval operations on my sinues because of this problem of air quality and dust, plus i almost died from one of the operations, i was suffering so much. Yes you can seal your duct system by buyind duct seal t instead of tape to tape all the corners of the vent system, tape wears out and gets brittle, the sealant you can buy at home depot, and you just brush it all over the connections of your ductwork, it comes in a container and it is like a thick paste and dries making a good seal for your ductwork.
So HVAC sent Tony Diaz to my house. I was at work so he was subjected to the most excruciatingly exacting woman on the planet (my wife). Tony impressed her with his friendliness, professionalism and the obvious jouneyman-level knowledge of his craft. He found literally --burnt-out-- parts in our system and replaced them. It cost us a bit but I know enough about the parts to see there was no gouging on the parts and a fair rate for the labor. It wasn't cheap but it was fair and worth every dime.
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.)
1. Ducts need cleaning mostly because they were not installed properly. There should be regulatory inpection and approval of clean and proper duct works on new houses. I was extremely unpset when I looked and found significant amounts of construction dust in parts of the ducts in my new house. There is apparently no way to hold the bullder to be responsible for clean ducts.
We bought 2 top of the line Lennox HAC for $29,000 less about $3,500 rebates, thinking they would at least last 10 years. Well, after 6 years, the system leaked. We are paying $1,700 to fix that leak. We thought at least it is still under warranty - yes BUT - the warranty covered $15 & the rest we were up for ,even though they advertise 10 year warranty. We are trying to sell & move out of high cost southern Calif & have looked at 20+ places in Arizona. Most of the houses we looked at were built from 1998 to 2005. We asked if the HAC was original & in most case it was - even though the highs were 115 to 120 & the lows 90F - versus where we live the highs run 85 to 95 & the lows are in the 60s. I asked the repairman WHY ours went out at 6 years. He replied that they just do not build them the same anymore. In Arizona, I did not see any Lennox - mostly Trane or Carrier. We had Fujistu in Australia which were fantastic - nothing went wrong in the 9 years we had them. Also, they had full induction motors not like the energy consuming 2 stage motors in Lennox. Maybe the Japanese built Fujusita still builds quality & the warranty is meaningful?

Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts or go down after cleaning. This is because much of the dirt that may accumulate inside air ducts adheres to duct surfaces and does not necessarily enter the living space. It is important to keep in mind that dirty air ducts are only one of many possible sources of particles that are present in homes. Pollutants that enter the home both from outdoors and indoor activities such as cooking, cleaning, smoking, or just moving around can cause greater exposure to contaminants than dirty air ducts. Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to health.


At the state level the rebates are still substantial. For example, switching to a zoned system can get you a $100 rebate from various A/C companies, and state rebates are also included. In Pennsylvania a high-efficiency air conditioner alone can get you up to $300, and a high-efficiency complete HVAC system can see up to $1000. Maryland's incentives get up to $1,250, with a $100 rebate on a tune up of an existing system.
Your cleaning service should involve all aspects of your duct work to maximize energy efficiency and air quality. This includes attending to the heat exchanger, blower, drain pan, plenum and coils as well. In the process, your service provider may find that you're facing larger issues than debris and build-up. The professional may recommend having your furnace repaired if they notice, for example, damage to your heat exchanger or blower motor. Generally, a furnace repair costs between $130 and $500. They may also find that an A/C coil needs to be replaced rather than cleaned and would then recommend A/C repair.
Multiple inventions within this time frame preceded the beginnings of first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899.[12]
He proceeded to clean each heat register by removing the grille and blasting it with an air pressure hose toward the duct opening thinking that the dust would magically be sucked inside. In one room this caused a ceiling smoke detector to go off because the excess dust fooled it into thinking there was smoke. I put my hand in front of a register he wasn’t working on and could hardly feel a suction. Although we discussed how I open and close damper doors, I realized later that he never checked, opened or adjusted them during the cleaning. He could have closed all but the one he was working on in order to increase suction results. His next step was to blast air into the duct and then attach a “squid-like” device that slapped around inside the duct as far as he could reach. This is important! In a newer house, ducts have long straight runs from the furnace. In older houses like mine they can turn and twist. In fact, the duct we have a problem with runs straight up from the basement inside a wall and turns 90 degrees into a soffit for three feet then into two 90 degree turns to get into the floor joist area for another two feet and finally a 90 degree turn up to the second floor register. When he cleaned this one he could only get three feet into the register with the hose or squid because of the turns. That was the case with most. Hardly what could be described as a decent cleaning.
Capacitors -- Capacitors help your HVAC motor start from a standstill. Over time they can weaken. As they weaken, they cause the motor to run hotter. This can shorten the life expectancy of your motor. Once a capacitor fails, the whole motor will stop working. You usually won't notice that a capacitor has weakened until your motor stops turning on.
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.....

I agree that good filtration and a sealed system will prevent the need for duct cleaning. However, when we do get called it is because the duct work has reached a noticeable state of restriction or dust or the homeowner is hyper-sensitive to these pollutants in their home. Most of the time we find that no filter or a cheap (99 cent) filter is being used or they have serious duct leaks in the system. If you are hiring a cleaner make sure they are using professional cleaning equipment which will consist of a rotating brush system and a vacuum source. Be highly skeptical of the contractor with no branded system or the guy who shows up with just chimney brushes and a shop vac. He will not be able to reach around all the corners or all the runs in your system and he will be taking your money for a superficial cleaning at best. Only trust a company that offers VIDEO inspection and more importantly.... a contractor who repairs, installs and seals ducts if a problem is discovered or heaven forbid, created. Good luck and get your ducts sealed if you do have a leak! It is one of the greatest energy losses to a home other than being poorly insulated.


Because an air conditioner moves heat between the indoor coil and the outdoor coil, both must be kept clean. This means that, in addition to replacing the air filter at the evaporator coil, it is also necessary to regularly clean the condenser coil. Failure to keep the condenser clean will eventually result in harm to the compressor, because the condenser coil is responsible for discharging both the indoor heat (as picked up by the evaporator) and the heat generated by the electric motor driving the compressor.
I read your article with interest and think it is a good start. One service that is always talked about is fogging ductwork for sanitizing. Many companies offer this service for disinfecting or adding a clean smell to the ductwork. Before any chemical or disinfectant is used, please read the MSDS (Material Safety Data Sheet). You might be surprise on what you are putting into the air stream. This is a high profit service and should be explored thoroughly before purchasing,
Those of you who read our posts regularly know that we built our reputation as a U.S. Veteran-Owned business that prides ourselves on giving people straight, honest answers to their questions...and there’s no question that makes people cringe more than asking, what does a new HVAC installation cost? Oddly enough, most contractors keep their air conditioning installation cost a closely guarded secret, as if the knowledge of how much it should cost will somehow change your decision when you have to buy a new AC. What I will tell you, is that the fair price of an HVAC installation will vary greatly based on the type of heating and air conditioning system installed, as well as the options needed or desired (Ductwork included? Zoning system?). In this article, we’ll discuss the five system features that affect HVAC installation cost, fair price ranges you can expect to pay for your new system, we will then perform an example calculation of how you can calculate a fair price, and finally, what you can do to keep from getting ripped off on your new HVAC installation price.

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. 

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.


Is duct cleaning worth it? There is not a yes or no answer that suits everyone. On an Air Force base, the system was not air tight and there was leakage around the filters. The system got dirty. A professional company was called out. The Duct was big enough that a technician could go inside the metal duct and clean it. There was a new Air Handler installed and things were sealed up better. in this case it was worth it.
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).
×