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Question DetailsAsked on 5/13/2013

how long does it take for duct cleaning 1100sft house

how long to duct cleaning 1100sqft house

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2 Answers


A typical 3 bedroom, 3 to 4 hours ,or more. A vacuum that puts the entire duct system under negative presure, will do the best job. Many are truck mounted systems. One that looks like an over sized shop vac , where the hose goes in the ducts, is not the best way to go, almost impossible to get to all the ducts that way.

The big question is why do you believe you need the ducts cleaned?

Check here , for what the EPA has to say about duct cleaning. A lot to read, but may help you make the best decission for you and your family.


Answered 7 years ago by BayAreaAC


Bay Area AC is on the money with their answer. Unless the buildup of dust and lint is so bad it is restricting airflow, there is little evidence it is harmful to most people, though of course it can make a horrendous mess and a very dusty house if it is knocked loose by extreme airflow near the heater (i.e. tornado or hurricane), or a good strong earthquake or someone banging on the ducts.

However, that said, if you have recently moved into a used house that has a lot of lint and dust already built up in the ducts, if you have anyone in the house with a respiratory disease or condition, a weakened immune system, hay fever, or a new baby, you might want to have a thorough one-time cleaning done, as well as looking into why there is so much dust/lint in the first place. Of course, those persons should not be at home during or for several hours after the cleaning, and the house should be carpet vacumned and well aired out afterwards before they come back home.

If dust is accumulating in your ducts, you need to look at the cause - in a modern system you should not get a noticeable buildup in less than 10 years or so. Not that they will pass a white glove test and not have any dust bunnies in the bottom, but noticeable wall buildup means grossly excessive dust entry, and almost always moisture condensation also - THAT is what turns dust buildup dangerous, as adding moisture to the dust makes for mold and fungus growth, and that CAN be very harmful.

A modern system should have a good multi-stage dust removal system - either multi-bank tight-fitting clamped in place (not just really loose slip-in) disposable HEPA filter elements, a HEPA filter plus electrostatic filter, or (in some large volume systems, especially in really dusty areas like the dust bowl and desert states) a powered cyclone filter plus HEPA filter. One thing many blended air systems (where outside air is blended with interior air being recycled) do NOT have but should have is that the recycled air should pass through the filters before going back into the heating chamber - otherwise all the dust and clothing and rug lint in the household air is just being blown back through the ducts unfiltered. This is commonly as big or bigger a dust source than the outside air is.

The second factor is moisture - if your system uses 100% outside air rather than blended air, not only does it burn about twice the energy it needs to, it is also bringing in a lot of outside moisture that can then condense on any cold ductwork. Blanket insulation of cold areas of ducting pipe can help, especially in cold outside walls or basement/crawl space runs. There are also variable-heat and variable-flow heating systems that use longer run times of lower temperature air for heating, rather than widely spaced shots of hotter air - this reduces condensation by keeping the ducts warm more of the time, and also maintains a more constant house temperature.

Another major cause of condensation in forced air heating systems is a cracked or holed heat exchanger. The furnace burns the fuel in an air mixture. That combustion exhaust then passes through ( or in some models around) a heat exchanger on its way to the exhaust chimney pipe. Meanwhile, a fan blows outside air (or blended inside and inside air) over (or through) this heat exchanger - just like a car heater blows outside or blended air over a small heater radiator filled with circulating hot engine coolant.

The problem with a cracked heat exchanger, aside from the fact that it can leak dangerous carbon monoxide and carbon dioxide into the interior air, is that a significant combustion product is water vapor. If this escapes into the ducts, it makes the dust "sticky" so it builds up in the ducts, as well as possibly promoting mold and fungus growth. I have actually seen a mushroom-like fungus jungle growing in ducts that were almost totally blocked with caked dust from this cause.

Therefore, it is important to have your heat exchanger inspected when your furnace is given its annual cleaning and servicing, and replace it if cracked or corroded through. The inspection will be visual, and there are also scent ampules that can be placed in the combustion chamber to smell if the odor comes out through the duct grills because of leakage. (Commonly cinnamon or clove or banana oil based, so the scent is not objectionable if it does leak). Heat exchangers cannot be safely (or in most jurisdictions, legally) repaired, and a service man cannot legally put a cracked one back in service after inspection. Some service men will inspect with a fiber-optic camera or a fibre-optic light (to look for light leaks) and this might be fine for some annual inspections, but it should be removed, brushed clean, and thoroughly inspected from all angles in bright light at least every 3 years or so - more frequently as required by law.

Another significant source of moisture is the furnace drawing the inside blend air to be heated from a damp basement or crawlspace rather that upstairs or all-room return vents (which is the right way to do it). This passes right through to the ducts and condenses as it hits cold ductwork.

My recommendation is to forget about the in-the-house vacumn duct cleaning systems - they are just grossly underpowered, and a good portion fo the dust passes right through the vacumn into the inside air, same as happens with a shop vac. To do the job right, though it costs 50% or so more, you need the truck-mounted high-volume vacumn unit to remove the debris by pulling a vacumn on the entire system, with the actual cleaning being by a powered brush snake or a rotating-head high-pressure air jet snake. These actually snake down into each vent while the other vents are taped over to restrict the air flow to one duct at a time, and as the clesning tools are snaked in, brush or blast away the buildup. My experience (in high-rise ducts running hundreds of feet) is the air jet ones remove the loose stuff and bottom grit OK, but fail to remove heavy caked-on deposits consistently - they tend to slab it off some places, and leave it intact in others, much like using a hose to wash caked-on mud off a driveway. I would recommend the rotating brush system if available in your area at reasonable cost (usually only available in urban areas). These in-duct removal system should still take less that a day to do the job - I would guess 3-4 hours if 2 dtory, maybe up to 6 hours if 3-story and a lot of different ducts, or if you have flexible ducts (you have to be a lot more careful with those, and some cannot be power brush cleaned).

Answered 7 years ago by LCD

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