How much suction is really needed for air duct cleaning?

50 years ago the most acceptable method of duct cleaning was to use a big duct truck, tie in an 8” hose and bang the ducting with a hammer and when possible throw a broom down and pull back the debris into the vac hose.

Then along came air pressure to the duct trucks and the cleaning quality skyrocketed, the truck chassis became more powerful and the fans and compressors in turn got bigger and bigger. Todays modern duct trucks run upwards of 12000-13000 cfms with 15” of static pressure. (for the carpet cleaners reading this a “truck-mount” in the duct cleaning world isn’t a carpet cleaning unit sitting out in the van running a 2” hose and if your telling your customers you have a truck-mount for duct cleaning then you should be ashamed)

But is 12000 cfms needed for duct cleaning ? it is for a duct truck. Having impressive suction out at the truck doesn’t mean much if you have to always run 100+ feet of hose from the street into the customers home. Its basic physics, the longer hose you run the less suction you will get at the end of it. The basic calculations on static pressure alone will reduce your static pressure at least by half on every 100 feet of hose. Typically the amount of suction you get at the furnace using a duct truck is in the neighbourhood north of 6000 Cfms after laying out your normal amount of hose, which is pretty respectable. Typically with 6000 Cfms its rare you would ever after to zone off a residential heating system for duct cleaning , the only downsides to the duct trucks are the super high start up costs, the extensive maintenance and repair bills the high operating costs and the time it takes to set up and take down all the hoses. High Powered Vacuum duct trucks were a great technology 50 years ago unfortunately they are not really in tune with todays reality of high labor costs, fuel costs, insurance and the list goes on.

If 6000 cfms should be considered the baseline for what is considered acceptable suction, then how do portables with only 2500 cfms fare in duct cleaning ?. 2500 cfms definitely is not enough suction to duct cleaning in a normal reasonable fashion, if your doing residential duct cleaning using a portable then you have to make a few sacrifices , you will need to take the extra time needed to zone off the ducting and clean only small sections of ductwork at a time or use 2 or more units and tie them into the ductwork in a strategic manner as to generate a respectable amount of suction. Most portables are big heavy machines and you wouldn’t have the room to park 2 vacuums near the furnace where they need to be tied into the ductwork so using 2 machines in a residential setting is unlikely. Normal portable duct vacuums pose as many problems as they solve in terms of low cost start up, they lack the needed suction and are really only feasible in commercial HVAC cleaning where its normal to have multiple vacuums running and you have the space to tie in a bunch a vacuums throughout a massive HVAC system.

The Hypevac 220 Volt Revolution series vacuums fit right in between the 2 scenarios above , the 220 volt vacuum generates a respectable amount of suction at roughly 5000 cfms ( depending on test factors), they may not have quite the full suction of a duct truck but they also run directly next to the furnace with only a few feet of hose so the suction is pretty close to using a duct truck, they still have the main benefits of a portable duct vacuum offering low initial purchasing costs, low operating costs (reusable filtration), the Revolution series both the 360 and the Hybrid vacuums are small and lightweight and you have the added bonus of showing your customer what came out of the ducts, and best of all you won’t cool off the house by sucking all the warm outside in the winter.