For fast duct cleaning across Los Angeles County, you’ll be delighted with the expert service and care you receive from Green Air Solutions. Already trusted in thousands of homes.
QUALITY DUCT CLEANING: A thorough duct cleaning can make all the difference, and Green Air Solutions has invested in the latest technology to do the job right. We can clean and brush all the way through your ductwork, as opposed to the ‘air only’ systems which only work closest to where it is being cleaned. Not only that but we can ensure that the debris is pulled out of the system, and the system disinfected with a kinder, indoor air quality-friendly solution that is completely hypoallergenic. When you want your ducts cleaned right, Green Air Solutions has the quality solution for you.
REMOVE THE ‘NASTIES’: We can help remove the ‘nastiest from your ductwork, including caked dust mite feces and existing build-ups of mold.
VENT CLEANING: We can also help clean your dryer vents, which can be a significant fire risk as hot air can build up in the vent and help lint in the dryer overheat. With the high levels of humidity coming out of the dryer, it’s also a prime area to find mold.
SATISFACTION GUARANTEED SERVICE: With Green Air Solutions, you can be sure that you’ll be delighted with the level of service you receive. We’ll be there on-time, when it is most convenient for you, and we offer the care and attention you deserve.
FRIENDLY AND HELPFUL EXPERTS: We’ll take the time to help answer your questions and help in any way we can. With Green Air Solutions you can be sure that you’re in good hands.
You’d Be Surprised What’s Lurking in Your Home’s Air Duct System
According to the National Air Duct Cleaner’s Association (NADCA), a typical six-room home creates over 40 pounds of dust annually through everyday living. In addition, the typical family generates a great deal of contaminants and air pollutants such as dander, dirt and chemicals. These contaminants are pulled into the HVAC system and re-circulated 50 to 70 times per day on average. Over time, this re-circulation can cause a build-up of contaminants in the air duct work.
If you’re looking to improve the comfort and energy efficiency of your home, the air ducts are an excellent place to start. After all, the typical duct system loses 25 to 40 percent of the heating or cooling energy put out by the HVAC system. At Green Air Solutions, we can help make sure your air ducts are leak-free, properly configured to direct air throughout your home, and properly sized to match your heater or air conditioner. We’ll use our advanced diagnostic tools to determine whether air duct repair or air duct replacement is necessary to get the job done right.
Today’s high-efficiency HVAC equipment is more sensitive than ever to bad ductwork. There are several reasons for this, including the fact that more powerful blower fans push more air through duct leaks. If you connect a new heater or air conditioner to an old, leaky, improperly sized duct system, you will never get the level of performance it’s capable of delivering. Get air duct inspections & testing from Green Air Solutions and rest assured that your duct will support your home energy performance & comfort, not detract from it.
The term cubic feet per minute (CFM) is ambiguous when it comes to the mass of gas that passes through a certain point because gas is compressible. If the pressure is doubled, then, for an ideal gas, the mass of the gas that passes by will also be double for the same rate of flow in cubic feet per minute.
Air distribution system ducts are designed to supply conditioned air from heating and cooling equipment to the living spaces and return an equal volume of air from the living spaces back to the heating and cooling equipment to be reconditioned. Ducts are typically located in unconditioned spaces such as attics, crawlspaces, garages, or unfinished basements and are made of thin materials (like sheet metal) that conduct heat easily. Due to extreme winter and summer temperatures in these spaces, 10 percent to 30 percent of the energy used to heat and cool the air is lost through the duct surfaces. In order to maintain temperatures at a comfortable level, the heating and air conditioning equipment has to work harder to make up for these losses. Thus, uninsulated or poorly insulated ducts reduce the efficiency of the heating and cooling systems and increase energy bills.
Uninsulated or poorly insulated ducts can also cause occupant discomfort, especially during the winter months. As conditioned air moves through uninsulated ducts, it loses heat through conduction. As a result, rooms served by long duct runs can experience “cold blow” because they typically have lower heating supply air temperatures. This problem can be more pronounced with heat pumps that deliver air at lower temperatures. Even when the furnace or air conditioner is not operating, heat loss occurs due to conduction through the duct surfaces.
The need for insulation can be reduced if the ducts are located within the conditioned space. In this location, any conductive losses and gains would be minimal since ducts would be exposed to indoor air temperatures. Some insulation is still required to ensure that the conditioned air is delivered at the desired temperature, and to prevent condensation on duct surfaces.
One of the big misconceptions about airflow is how to determine how much air will flow through a certain size duct, or conversely, determining what size duct you need to deliver a certain airflow. You would not believe the range of flows I have heard as “rules of thumb”. This assumes that you have done the calculations necessary to determine how much air is needed in a room. That will be a different series of blog posts, to be sure.
Duct sizing is covered very well in ACCA Manual D and is fairly straightforward. For now just suffice it to say that there is a very important number called “Friction Rate” that determines the relationship between duct size and airflow. Friction rate describes the average pressure drop per 100 feet of duct in a system. Notice that this number is unique to a system, not just an individual duct run. For example, all things being equal, an 8” duct at the end of a long convoluted duct system will not deliver as much air as an 8” duct on a very short straight system. This is because everything that the air passes through has an impact on how much air comes out of the very end. Friction rate is a wonderful number because it takes into account how much static pressure you fan is providing, how much of that is left after you subtract out the big-ticket items like the coil, filter, supply registers and return grilles.
But, you say, most systems do not have runs that are 100 feet long! What use is that number that is “per 100 feet”? Actually, if you look at something called “equivalent lengths” a duct run can be well over 100 feet “long”. Equivalent lengths are numbers that can be looked up in an appendix of ACCA Manual D. This is where a fitting such as a t-wye or elbow is assigned a number that represents a length of straight duct that that has an equal pressure drop. For example a t-wye might have an equivalent length of 10 feet. A ninety degree elbow might have an equivalent length of 15 feet. A round start collar coming off of a sheet metal supply plenum can have equivalent lengths approaching 30 feet or more. When you add up the actual lengths and the equivalent lengths, it adds up quickly.
Even if the length of the run is very short, you can still use friction rate because the 100 feet is just a number they decided to use. They could have used pressure drop per 10 feet or even 1 foot. It just adds more decimal places. Don’t dwell on it. Move on. Get over it. Just don’t forget about it. One of the biggest mistakes I’ve seen contractors make is to confuse total operating static pressure (inches of water column) with friction rate (inches of water column lost per 100 feet).
The details of how to calculate friction rates are covered later, but a very common friction rate for a reasonably well-designed designed system is 0.1 iwc/100’. You can take that number and using a duct slide rule, duct calculator, or friction rate chart and determine duct size for a given airflow or determine how much air will come out of a given size duct.
Now, I’m taking a huge risk by putting this table out there and I will probably get a lot of grief for it, but here it is. The danger is using it on systems where the friction rate is something other than 0.1. (I use this table all of the time as a first guess, ball park number and it works fine. Of course, I fine-tune the calculations later, but it’s always pretty close. It’s a hundred times better than some of the numbers I’ve heard contractors rattling off.)
One of the first comments I used to get on my designs was that odd size ducts are not used. Did I mention that I have done about 2000 residential HVAC designs? Ninety-nine percent of them were for medium to large production home builders. What they meant to say was that odd size ducts are not normally stocked by their local wholesaler. That’s because none of the contractors used them. Supply, demand, etc., etc.
What if you did a detailed load calculation (ACCA Manual J), carefully selected equipment (Manual S), and knew exactly how much air each room needed. Now you are in the process of sizing ducts (Manual D). Let’s say that you had a room that needed 95 cfm. If you were a contractor who did not use odd size ducts, your choice would be between a 6″ duct, which does not give you enough air, or an 8″ duct with gives you almost twice what you need. Which would it be? Six inch, of course. Suck it up and use 7″ duct, cheap skate!
Here’s some other interesting ways to use this table. If you have a room that needs 197 cfm and another right next to it that needs 72 cfm what kind of t-wye will you need to serve these two rooms? To deliver at least 72 cfm, you will need a 6″ duct. To deliver at least 197 cfm you will need at least a 9″ duct. The trunk that serves these two ducts needs to be able to deliver 72 + 197 = 269 cfm. Using Table 1, that means a 10″ trunk. By the way, a duct that is split into more than one duct is called a “trunk”, just like a tree. Ducts that are on the end of a trunk and terminate in a register are called . . . branches! How about that? And that’s why we call registers “leaves”. Just kidding. Nobody does that.