What happened to the dual fan vacuum motors?

[Mike81]

Just wondering why majority of modern vacuum cleaners only have one suction fan and when it changed?
I remember when I was younger and used to disassemble a lot old vacuums from the 70's-80's. All of them had 2-stage (2 fan) motor.
Is this the reason why many modern vacuums are high pitched screamers LOL. Guessing RPM has to be much higher due to the single fan design.

I hope my question makes any sense

 

[kirbysthebest]

My guess with no other knowledge

Single stage are cheaper to produce.

 

[Mike81]

Well it might be one reason. Assumption: When motor wattages increased dramatically manufacturers didn't use twin fan system anymore. Consumers choose vacuums too often just looking how "powerful" the motor is.
But it is now changing in the EU.

 

[kenkart]

Single fan vs dual

Believe it or not, you can move more air with a single fan...Apex Strato cleaner, Sunbeam and Westinghouse are good examples of this, but dual fan motors such as used in Filter Queen and Compact develop more sealed suction..so its a toss up..But , most single fan units do not last as long.,and im sure that's why its done today, if it burns up quicker, you buy a new one quicker...that's the industry position today.

 

[kirbykid63]

Perhaps Weight

I also noticed this and I felt weight has something to do with it. Everone seems to be looking for a lightweight vacuums.

 

[tolivac]

Another factor-some vacuum companies are going to the "tapered fan"approach such as Meile and Kirby.The trailing edges of the blades are shorter than the leading edges.This results in a more efficient fan design-and the motor requires less energy to run it-but the performance is as good or even better than the older dual fan design.But when dual fan is mentioned-another thing-are the fans in series-like the motors described-or parallel?-The GE and Singer twin fan uprights-fan on each end of the motor shaft.Series more "pressure" Parallel-more airflow.

 

[Mike81]

A lot of interesting thoughts and info given here.
My personal experience is that 25 year old twin fan 1000w bagged vac has same amount of suction than new single fan 2100w powerful bagless vac.
On the other hand new single fan 2200w bagged vac has 108 cfm measured from the hose end and.that is A LOT of airflow from clean air vac.

 

[sprockkets]

Well Riccar and family has their tandem air vacs. I'm not convinced it is necessary. They claim to offer the benefits of bypass which is good filtration and good hose suction with the benefits of high floor nozzle suction. I think both motors use 1000w.

Personally I can't see why bypass can't achieve the same level of suction for the floor nozzle but that's me. I've used their vibrance and their predecessors, from Panasonic, and all work well.

 

[tolivac]

The motors in the Tacony tandem air machines are like 6A each.-12A(1200W) total with BOTH motors going as in the carpet clean mode.For bare floors and hose mode only one motor runs-the clean air motor.I am quite pleased with my tandem air machines.up there with my Kirbys.

 

[sprockkets]

Yeah I should clarify that isn't 1000w each motor, but total, at least that's what I remembered going to Ricarr's website. In a way it does make some sense that the brush motor can also again function as a suction motor next to the floor nozzle.

Saw the Maytag equivalent for $900 this past Fri at my local shop.

 

[ultralux88]

Hans (Kenkart) nailed it

The difference between a singe fan and a dual or triple fan motor from an engineering point of view is what design will give the best performance for the cost, weight, size requirements that they are given. As Hans said, a single fan motor can move more air while adding more fans will cause a loss in ai flow, but an increase in sealed suction. Personally I don't feel there is a connection between how many fans a vacuum motor uses and how long it will last, its mostly coincidence that most modern, low quality motors are single fan. Many high quality machines like Miele and Sebo use single fan motors that will run for years. The reason that more and more motors are going to a single fan design is that modern technology and design has given us the ability to make fans that are more effective, think the fans you've seen that taper to a taller fin in the middle. These new fans give the advantage of being able to get the better airflow of a single fan motor, but also create as much suction as a twin fan design. And to go even further, both Domel and Ametek now make motors that have 2 of these 'vortex' fans, my central vac has 2 5in Domel motors with dual vortex fans, and its a real beast.

 

[n0oxy]

one and two stage motors

The motors that we think of as "screamers" are almost always one stage motors, but not all one stage motors sound this way. And, just because a motor sounds this way, doesn't mean it's a bad motor, though many of them are. Personally, I like the sound of the two stage motors much better, for example, the motor in the Electrolux 1205, or the super J, or the Ametek motor that was used in older vacuums such as the lady Kenmore and Eureka canned ham with the vibra beat attachment. The Kenmore canisters from the 1970's and 1980's also had a nice sound and I think these used two stage motors. Almost all central vacuums use motors that are at least two stage and sometimes three. On the other hand, most canisters and clean air uprights that are currently made use one stage motors and that's where we have the screamers. I think there are a couple reasons for this, one stage motors are lighter and probably cheaper to produce. On the other hand, they spin much faster so many of them don't last as long, though that's not always the case. The motor used in the Miele is one stage, it has a higher pitch but the sound is not as noticeable as on some other vacuums such as the Dyson. I think Sebo uses Domel motors in their uprights, not sure about the canisters, but the Sebo canisters have somewhat of a high pitch as well. I only have two canisters that use two stage motors, the Perfect C101 and the Metrovac canister. Interestingly, on the Metrovac, it does seem to have more airflow than suction, you actually hear the air going through it much more than you hear the motor itself. As far as what is better, more suction or more airflow, I think the best answer there is you need a decent amount of both to clean well. As with many things in life, a balance is a good thing. I would think a water lift number of 80 or more and airflow of 100 or more would be sufficient. The dyson vacuums love to boast about how much suction they have, but in many cases, their airflow is very low. On the other hand, the dirty air uprights have great airflow but not a lot of suction which will work for cleaning carpets, but these vacuums do not work well with attachments. Getting back to the sound, Ametek does make some one stage motors that don't have the screamer sound. The Ametek motors in my Perfect, Powr-flite and Windsor backpacks are higher sounding than two stage motors, but not as annoying as the Dysons. This would also apply to the motor that is used in the plastic Perfect canister, c103 and the Aerus classic.

 

[sebo_fan]

Well there's something called Sound proofing which a few of the German brands fit. I know that the E1 Airbelt I have has more whoosh of air than whine.