Hoover Convertible (U4007) Airflow Losses

[wyaple]

The first measurement was easy to get, the last one (CFM at the nozzle) required me to build an airflow box. I think this pic should easily illustrate where and by how much CFM is lost in this machine. This is excellent performance from a 32 year old cleaner.

From the base of the machine to the nozzle, there is a loss of 120-100 = 20 CFM. This represents about a 17% loss from the direct air motor. Of course as the bag fills, the airflow will drop as well.

Last note: the rug plate opening is on the small side, measuring 23 square inches BUT the CFM density tops my charts, about 4.4 CFM/Sq. In. If you ever wondered if this old beast was still capable of deep cleaning, it certainly is. This is my first Hoover Convertible and I was completely blown away with it's performance (and great sound quality). This old dude actually bests my 2012 Kirby Sentria II in CFM density.

Bill

 

[bnsd60m9200]

U4007 was made from 1973-1975. and yes convertibles had gobs of airflow. they didnt however have the best waterlift (suction). but airflow is what cleans carpets, not suction.

 

[kloveland]

beast was still capable of deep cleaning, it certainly is.

We already knew that. But it is nice to have someone confirm it with actual readings. Some of the air loss could be from around the converter door under the plate. 


 


 

 

[wyaple]

Thanks for the more accurate manufacturing info

I wasn't too sure when this machine was made, then I saw pic #1. The foil tape has a date of 6/85. Maybe that was when it was last serviced? But, when was the last time someone dated foil tape? So, I guessed. BUT, I was sincerely hoping that it was a 70's machine. The oldest vacuum I have before picking up the convertible is a 1980 Lux 1401-B, so I'm very happy that this one appears to be older.

Pic #2 show the manufacturing data. Maybe the serial number is 0042651?

Pic #3 shows the hood.

Bill

 

[wyaple]

Updated My Main Pic To Reflect New Year Info...

If someone can pinpoint the exact year, let me know!

Kenny,

This was one of the machines of my childhood. Everybody had one. I was never allowed or shown how to use vacuums even though I was fascinated with them. I didn't have any idea that Convertibles could possibly keep up with a modern Kirby. I haven't measured the suction yet, but if I can make an adapter to fit the fan directly, I'll post the results.

Bill

 

[gottahaveahoove]

THis is one of my absolute favorite cleaners.

I have 4, I think. Another member is interested in purchasing one of them. 2 of mine came directly form North Canton. One, from Mr. Dick Pike, himself. I had it completely serviced in Scranton. It sounds, looks, and operates like it just came out of the box.

 

[bnsd60m9200]

hi john, that was me. whens best to call you? getting this close to the convention it may be better just to take it with you if you're driving and save the pain of packing and shipping.

 

[mike811]

Kirby?

How about Kirby? Have you tested airflow from any Kirby?
It would be nice to know, because everyone says that Kirbys have very good airflow.
I have a Kirby Gsix 2000 Limited Edition

 

[pr-21]

I was obsessed once years ago about water lift, until someone on this forum explained the difference between water lift and air flow. I even have a water lift gauge which I do not even use anymore. Rainbows do not have great water lift, but Rexair sure knows about airflow. If my Rainbow SE PE had the newer power nozzle that the E2 Black has, I believe it would out clean the E2 Black, due to the E2 Black having the added hepa filter, which in my opinion is not necessary. If you don't pick up non wettable material, which I do not, it will stay clean for years. I actually changed mine and cut it open and it was still spotless, the same as another member on this forum has just done recently.

Not trying to hijack this thread, I appreciate all the testing you have done, it has been interesting to see. Thank You

PS I grew up with Eureka's and Hoover's. I recently purchase a NOS Eureka 2033 on Ebay with a 3.5 amp motor and put a Vibra Groomer in it. Excellent cleaner even at 3.5 amps.....

PR-21
Bud

 

[wyaple]

Mikko,

I have a Gsix and it tests at 120 CFM at the nozzle with a clean HEPA bag. BUT, I call your attention to "airflow density". While the Kirby does have more total airflow than the much older Hoover, the CFM per square inch is lower in the Kirby. My measurements say the Kirby Gsix is 3.54 CFM/Sq. In. versus the Convertible's 4.36 CFM/Sq. In. The bottom line is that while both machines are excellent, the older Hoover should pick up more dirt although it would take longer to do that due to the smaller nozzle size (Hoover=23 Sq. In. versus Kirby=33.8 Sq. In.).

Bill

 

[wyaple]

Bud,

I think you have airflow and water lift flipped? Rainbows aren't known for great airflow. I restored two SE's now and the 1993 model does 60 CFM at the hose while the 1997 SE PE does 65 CFM at the hose.

Water lift results are below:

Rainbow D4C SE from base (empty bowl) = 58" lift
Rainbow D4C SE from hose end (empty bowl) = 54" lift

Rainbow D4C SE PE from base (empty bowl) = 60" lift
Rainbow D4C SE PE from hose end (empty bowl) = 54" lift

Unfortunately, by the time you measure airflow at the power nozzle, the CFM drops dramatically. The 1997 SE PE tests at 33 CFM and the older 1993 SE (different PN) tests better at 42 CFM.

Please understand, I'm not saying these machines don't pickup dirt, but if Rexair would at least double the airflow, I'd bet they would do much better. I enjoy using both of them and watching what accumulates in the water bowl.

Bill

 

[mike811]

Nice to hear that Kirby does have a great airflow.
By the way. How I can get the Kirby baird manometer or how it is called. I mean airflow meter to fit the Kirby or one what many vacuum stores use in their youtubevideos. I remember that it has 0 to 10 range.

 

[wyaple]

Mikko,

Here's some Baird company info:

Baird Meter Inc
1932 North 11th St
Springfield, IL 62702
Phone: (217) 522-5858

Hope this helps. I bought mine 2 years ago for about $30 USD.

Bill




http://https//www.facebook.com/BairdMeterInc/?hc_ref=PAGES_TIMELINE&fref=nf

 

[kirbyvertibles]

That is a vac shop repair tape. Most would just stamp the vacuum itself but whoever did this was respectful enough to use a piece of foil tape.
As stated before this was 73-75 but no real way to tell which of those years.

 

[wyaple]

Updated Performance Measurments For My Convertible

And I'm very happy with the results! As the pic says, I replaced a very worn top bearing (thanks to Andy R.) and re-greased the lower bearing after finding it partially frozen. Looks like I was able to get a 7% increase in airflow at the nozzle.

Bill

 

[vacuumlad1650]

Glad it's working out! I looked at Steel City Vacuum and they Type A full tube is unavailable but a complete bag assembly (bag, bellows, bag ring, and full tube) it $50...you might want to try HEPA F&G bags.
Andy