Thread Number: 34757  /  Tag: Recent Vacuum Cleaners from past 20 years
Suction vs Airflow: No high suction needed to clean well
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Post# 375347   7/14/2017 at 05:41 (341 days old) by Mike811 (Finland)        

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I have done several videos about this topic and results have been always the same. High airflow vacuum with very low suction picks up much better than the low airflow vacuum with the very high suction.
Some people have don't seem to believe this.
Let's take Dyson for example. Dyson vacuums have very high level of suction, but poor airflow. They claim is "highest suction of any vacuum cleaner from the cleaner head". It might be, but it doesn't make it clean well, because of the poor airflow. I have seen many impressive looking Dyson demonstration videos where it agitates and picks up very well from the low pile carpet. Dyson never talk about airflow, because they know, that their vacuums have a poor airflow.
So I tested my highest suction (poor airflow) vacuum what I have (Vax/Hoover Air) vs Kirby G6 with high airflow (poor suction).
You can clearly see the difference.

Special thanks to Bill for inspiring me to do these tests.


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Post# 375384 , Reply# 1   7/14/2017 at 20:19 (341 days old) by wyaple (Pickerington, OH)        

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Your welcome! It's nice to inspire people to see something different. As a reminder, my Dyson DC14 has 112" of lift at the hose and 59 CFM at the nozzle. A G6 (just like yours) has 32" of lift at the motor base (low speed) and 120 CFM at the nozzle. The Kirby deep cleans easily and the Dyson simply can't at all.

He Who Vacuums Last Wins Nothing a Tale of Three Dysons

One Pass Deep Clean Test Kirby Sentria II


Post# 375650 , Reply# 2   7/21/2017 at 09:40 (334 days old) by Sebo4me (Cardiff)        

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Thank you for all your videos I have learnt a lot from them 😊

Post# 375655 , Reply# 3   7/21/2017 at 11:57 (334 days old) by vacuumguy91 (Raleigh NC)        

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amazing...I've been researching to buy a Kirby...this just motivated me more.. haha thanks so

Post# 375660 , Reply# 4   7/21/2017 at 16:10 (334 days old) by kenkart (Mocksville, NC)        
I agree totally

This is why old straight suction uprights clean ok,and why high airflow canisters such as Apexes Strato Cleaner or the Sunbeam Dual Deluxe outclean many newer machines, I have a NSS Pig that really does not have a lot of suction, but the airflow is so great that it outcleans just about anything else.

Post# 375661 , Reply# 5   7/21/2017 at 16:12 (334 days old) by kenkart (Mocksville, NC)        
Also why

A old Kirby with the hose attached will seem to have no power, but will do dusting chores quite well...lots of airflow!

Post# 376049 , Reply# 6   7/28/2017 at 20:17 (327 days old) by AlexHoovers94 (Manchester UK)        

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You are HOT.

Post# 376060 , Reply# 7   7/29/2017 at 04:27 (326 days old) by Sebo4me (Cardiff)        

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I'm quite cool this morning Alex. Where's the summer gone?!

Post# 376063 , Reply# 8   7/29/2017 at 06:26 (326 days old) by AlexHoovers94 (Manchester UK)        

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Post# 376074 , Reply# 9   7/29/2017 at 13:10 (326 days old) by DrSnuggle (Sweden Stockholm)        

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Sorry Mike81 for popping up here like this. I am not the one to think suction is more important. Maybe I am burning all bridges here, but I do like to learn. And questioning thingsis a good way to learn.

I do believe that air-flow is the most important factor between suction and air-flow. But one internet site claims that the air-flow is proportional to suction. If I interpret that right then it means that two identical Kirbys, apart from one having higher sucktion than the other, the one with more suction also has more air flow. Hence suction matters if you wish to have great air-flow.

Or have I been missinformed? I have no problem changing my mind so tell me, please.

Another thing some people claim is that suction effects the vacuums ability to pick up larger and more compact things. They claim that is a reason why suction also matters. I do not know so please comment on this as well.

Air-flow is effected by a lot of things, right? Different resistence you may have in the vacuum (small bag, HEPA-filter, multi cyclons). So for general cleaning performance of carpets/rugs I do agree that direct-air is superior to most clean air vacuums.

Post# 376108 , Reply# 10   7/30/2017 at 00:58 (326 days old) by Mike811 (Finland)        
Suction vs airflow

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Great to see you here!
Now without the suction there is no airflow and vise versa.
Different vacuums have just a different balance between the suction/airflow.
I am not professional about these. All what I know is from my tests and from the other videos. You have seen that the high airflow/low suction vacuum like the Kirby can remove flour under the carpet much better than the high suction/low airflow vacuum.
Now suction is needed to remove heavy items, but only if the nozzle is VERY close to it. Airflow will move it to the vacuum.
One example: Air driven turbo brush is one that needs both suction and airflow. Because the turbo nozzle has tiny hole where the air goes to the turbine, airflow will be greatly restricted. Suction will force the air through the tiny hole and help the airflow.
However the Kirby (at least my G6) has enough suction and certainly airflow to spin the mini turbo brush quite fast. Full-size turbo brush doesn't spin so well with the Kirby. It's just because of the low suction.
When the Kirby is in the carpet vacuuming mode it has very large diameter and simple "ducting" paths. That way it can keep the massive airflow.

I hope this will answer some of your questions :)

Post# 376133 , Reply# 11   7/30/2017 at 11:30 (325 days old) by sptyks (Skowhegan, Maine)        

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Here are two videos that describe the difference between suction and airflow:





Post# 376136 , Reply# 12   7/30/2017 at 11:58 (325 days old) by DrSnuggle (Sweden Stockholm)        
Thanks sptyks (and Mike81)!

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The second video I have seen (great video) and that one is one that made me think.
Suction is measured without airflow, hence resistence within the vacuum should not effect it. So the reason, I think, why bagless has lower airflow then bagged vacuums must be the turbulence created by the multi-cyclons. And that makes me think that mono-cyclons has better airflow than multi-cyclons, but I have no instruments to measure that.

Post# 376137 , Reply# 13   7/30/2017 at 12:28 (325 days old) by Sebo4me (Cardiff)        

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From what I understand a vacuum cleaner with high suction will have more airflow at the end of the hose than a vacuum cleaner with lower suction.

Post# 376148 , Reply# 14   7/30/2017 at 14:50 (325 days old) by Rolls_rapide (Scotland)        


High suction = low airflow, (e.g cylinder cleaners),

High airflow = low suction (i.e direct air Hoover uprights).

One of the old Hoover Alpina brochures had a graph purporting to show the relationship of airflow to suction.

Post# 376149 , Reply# 15   7/30/2017 at 16:37 (325 days old) by DrSnuggle (Sweden Stockholm)        
An X type graph

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I think I got it now. The graph would be like an x, one goes up then the other one goes down. A vacuum normally has strong suction but rather low airflow, but a kitchen fan has low suction and high airflow, right?

So suction and airflow co-exists but how do a vacuum buyer know the optimal balance between suction (water lift) and airflow? Maybe a stupid question if the seller specify both measures on the box of the product. Or is it enough to just look at the airflow?

This is so interesting and it has been covered before on this forum I can see.
At some point I thought airwatts was enough, but now I don't think it is particulary useful.

Post# 376151 , Reply# 16   7/30/2017 at 17:00 (325 days old) by n0oxy (Saint Louis Missouri, United States)        
suction and airflow

You actually need both to clean effectively. An example of all airflow but no suction would be a table fan, lots of air but not as much force behind it. You could also see this with a canister vacuum by opening the bag door and turning it on, you will feel lots of air moving but not a lot of force. Similarly, if you use a very small attachment you will have lots of suction but not as much airflow, it will feel powerful if you put your hand over it, but other than that, it won't clean very well. The dirty air uprights are very good at cleaning carpets, but for attachments, a canister will be far better. This is why I like canister vacuums, especially a power nozzle canister for cleaning carpets, they provide high airflow and high suction.

Post# 376199 , Reply# 17   7/31/2017 at 20:46 (324 days old) by wyaple (Pickerington, OH)        
In case anyone missed my measurements

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here's something to chew on:

Dyson DC14 has 112" of lift and 59 nozzle CFM
Hoover Tempo has 80" of lift and 80 nozzle CFM
Hoover Convertible has 25" of lift and 107 nozzle CFM
Kirby G6 has 32" of lift and 120 nozzle CFM

The Dyson cleans the worst, the Tempo is OK, the Convertible is very good and the Kirby is fabulous. You could also notice that as suction increases, nozzle CFM decreases. These machines are different types of course...


Post# 376204 , Reply# 18   8/1/2017 at 01:59 (323 days old) by floor-a-matic (somewhere)        
high airflow=high suction

a ridgid shop vacuum (when using the larger diameter hose) but a bit less airflow when using smaller diameter hose

Post# 376207 , Reply# 19   8/1/2017 at 02:27 (323 days old) by AlexHoovers94 (Manchester UK)        

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I don't get what this obsession is...Who really cares as long as the carpet is clean for the most part...We have had the same carpet for the last 20 years, cleaned with several types of cleaners...It hardly looks any different than it did originally, apart from it has faded slightly.

Post# 376211 , Reply# 20   8/1/2017 at 07:51 (323 days old) by Mike811 (Finland)        
Many good vacuums in all categories

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I personally like to do these test just for fun.
I like big variety of different type vacuum cleaners what I have. I mean bagless, bagged, dirty air and clean air. In each category is many well cleaning vacuums.
My personal point is just to show the differences in different type of vacuums.
These differences are fairly small for the normal consumer.

It just make me think when the Dyson DC65 doesn't even touch the flour under the carpet, but Kirby Sentria II removes it completely.

Post# 376216 , Reply# 21   8/1/2017 at 09:24 (323 days old) by DrSnuggle (Sweden Stockholm)        

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I feel a responsible for kick starting this thread again. And I like the input.
Thanks for your responses🤤

Post# 376218 , Reply# 22   8/1/2017 at 10:25 (323 days old) by Sebo4me (Cardiff)        

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Haha I agree with what you say Alex but some people like me are geeky about vacuum cleaners

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Post# 376219 , Reply# 23   8/1/2017 at 10:45 (323 days old) by DrSnuggle (Sweden Stockholm)        
Like being a child again!

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My last response was written on the subway on an Iphone so now some additional questions I have. I just want to learn (but I do agree with AlexHoover94) and it is fun in a childish way.

I was looking at your channel vaclabs and could you do an airflow test with a hose attached to a direct air vac (people say it will lose a lot of airflow) and compare it with a clean air high quality vacuum (e.g. your Miele canister or the green Riccard)? Just for fun of course. The nozzle test you (and vacuumtests) has already done, showing the Kirby to perform the best (I am more pragmatic as AlexHoover94 + n0oxy, but I am interested).

And if you or vacuumtests have already covered a hose test then please post a link.

My home is mostly bare floors and low-piles so I do not feel the need for a Kirby, but I can definitely see that it is one of the best Quality vacuums. And I am no friend of chinese crap. I agree of buying US-products if you live there. I live in Sweden and would buy Swedish if not all was sold out already.

Post# 376220 , Reply# 24   8/1/2017 at 11:30 (323 days old) by Mike811 (Finland)        

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I almost feel that I went too far with these tests. I guess I am a vacuum geek then LOL

Now keep in mind people that one of my all time favorite vacuum cleaners come from the 80's and it's not the Kirby. It's the Philips P74 Electronic. I like it much better than anything made today.
And the most shockingly my favorite modern upright is the Shark Rotator Lift Away Pro. AND I just ordered new Shark Rotator Slim Light Lift Away NV340UK. I don't even shame on that :D

My all time favorite Vintage Philips P74 Electronic:

Post# 376221 , Reply# 25   8/1/2017 at 11:32 (323 days old) by Rolls_rapide (Scotland)        
An X type graph

No, I don't think the graph was an "X" shape.

I can't remember now, but it might have been a loose "U" shape, or an inverted "U".

The graph wasn't in the multi- cleaner Hoover 'Collection' brochure. I think it was in one of those 'stand alone' fly-sheet brochures for the Alpina range only, which consisted of between 2 and 4 sides of A4 paper.

Post# 376222 , Reply# 26   8/1/2017 at 11:55 (323 days old) by DrSnuggle (Sweden Stockholm)        
U-shape graph

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A U-shape is what it should be if you plot it right and you reach a peak where suction and airflow is the best. Here is a link to why I said X shape (look for Suction versus Airflow).

Vacuumtests: Sorry, but this is interesting and your the reason for it :-). On the contrary I am really enjoying this thread. And obviously others as well I Suppose. No, you should feel proud of what you done. I am also a geek so.. Not only vacuums, but chess, statistics, cats....
I love vacuums in a different way then you but that is another thread some one started for that topic. I am not a premium member though so I have to pick my threads.

Post# 376239 , Reply# 27   8/1/2017 at 19:05 (323 days old) by wyaple (Pickerington, OH)        

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Here's an airflow test of four of my canisters. The best one by far at the end of the hose is a...wait for it...upright. With a decidedly underwhelming 40" of lift, a 2013 Kirby Sentria II in canister mode sucks to the tune of 120 CFM. Proof you don't NEED high suction to attain high airflow. To compare, a $1000+ Miele C3 does 101 CFM at the end of it's hose. The Miele definitely has more suction, but the airflow is worse.

Remember: Airflow is literally the speed of the air and suction is the pressure (force) of the air. For the most part, you can feel suction easily, but not airflow (unless you put your face in your vacuum's exhaust).

Bill (VacLab)

Post# 376240 , Reply# 28   8/1/2017 at 19:21 (323 days old) by wyaple (Pickerington, OH)        
Ametek Monster Motor Graph

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I've posted this many times before, but here is an example of a large, powerful canister motor. Peaking at 675 Airwatts makes you think this nearly 14 Amp baby has massive airflow, right? But you would only achieve that if you hooked up a 2" diameter hose! Using the typical 1.125" hose, the airflow plummets to 106 CFM. Hook up a power nozzle with its wands, u-joint, and seals and the result will most likely be in the mid 80's. Oh, it'll FEEL like it can "suck the paint off the walls", but deep cleaning will suffer dramatically.

BTW, all motor graphs are not like this one, they vary in shape dramatically.


Post# 376246 , Reply# 29   8/1/2017 at 22:06 (323 days old) by Mike811 (Finland)        

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Unfortunately many manufacturers show the airflow rating only measured straight from the motor. I have seen even Miele and Sebo doing this and claiming huge cfm figures. Sounds good, but it's far from the real cfm.

158 CFM. Really?

Post# 376250 , Reply# 30   8/1/2017 at 23:00 (323 days old) by DrSnuggle (Sweden Stockholm)        
Who needs CFM or waterlift when....

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Well Mike81, thanks god we have a standardized label system for vacuums in Europe (EU) :-).

(I am kidding of course)

Mike81: Where did you buy your Baird meter? I am so taken by this I would like to compare my own vacuums (not for videos, just for knowledge).

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