So you have decided to get the duct-work in your home cleaned. You search Air Duct Cleaning and call two local service companies for estimates. I walk in and tell you its going to take about 6 hrs for myself and a helper to properly clean your system. One of my competitors walks in and tells you he can do the same job maybe even for less money in 2 1/2 hrs by himself.
Your gut tells you there is more to this story and my advice is to listen to your gut.
When we clean your home we are going to hook up a device to your central duct system that we refer to as a "Negative Air Machine". By negative we mean negative air pressure or in other words from the moment we begin the cleaning process you can go to any point in your system and find that the air is being drawn back toward our machine. Several things have to happen to accomplish this and this is why it takes us longer to clean your system. First we need to bring in and assemble this machine somewhere near your main duct line, Usually in the basement. We will hook it first to your supply trunk line then later to your return trunk line. We then go to each register in the house and seal it so that all of the suction of the vacuum (about 3000 cubic feet of air per minute) will be concentrated on the area we are cleaning at the moment we are cleaning it. Then we will bring in a host of tools some of which are powered by a large truck mounted air compressor on our vehicle. Others are attached to a chord-less drill and driven through the duct-work. With a second protable HEPA vacuum we will, one by one, open each register and vacuum out the dirt both on the register and in the duct connection just below it. We will then use the tools I described to reach, dislodge, and move the internal dirt in the system back to the main vacuum or Negative Air Machine as it is called.
So why does our competitor say he can do it in 2 hrs. Most likely he is using a one step system that involves a rotary brush attached to the end of a small vacuum nozzle that is passed through the duct. The diameter of the vacuum he is using is about 2.5" after all it has to pass through the duct register. The diameter of our vacuum hose is Twelve inches and yes in this case "Size Does Matter". The more air you move the more particulate you are going to capture. Even when we are using our small 2 1/2" vacuum the main vacuum is still running to catch anything that the small vac misses. His vacuum is only going to pull dirt that is within a few inches of the nozzle and he is counting on every piece of particulate that the rotating brush is dislodging going directly into the nozzle. Its ridiculous to think that is going to happen. first of all as you are rotating that brush through the duct work you a vibrating it and dislodging dust and debris that is 20ft away. That is why we put the whole system in a vacuum. Even if we go to lunch the vacuum remains on to ensure no particulate gets back into the house. In realty his small vacuum will pick up the stuff that's close and a large percentage of the dirt will float back and contaminate the duct that was just cleaned or float out of the registers the next time the system is turned on.
When we are done we will professioanlly seal the opening we made to accomadate the negitive air machine. We do this with pre-made metal patches that are first screwd in place and then the edges are sealed with metallic tape. These are permanant closures and they take time to install correctly. Our competitor just picks up his vacuum and leaves.
The Moral of the story is this, If your having your ducts cleaned ask what the diameter of the vacuum hose is that will be used to clean your system and don't be afraid to say "Bigger is Better"
Ductz Indoor Air Professionals