Legitimate shop vac reviews?

[Ole Anderson]

http://www.woodworkersjournal.com/shop-vacuum-roundup/
http://www.finehomebuilding.com/tool...shop-vacs.aspx
http://www.consumersearch.com/shop-vacs
http://topreviews.best/main-review/b...FQoNaQodXuYFbA
http://www.popularmechanics.com/home...acuums-tested/
http://shop-vac-review.toptenreviews.com/
https://thoroughlyreviewed.com/tools...y-vac-reviews/

Can't say which of these are legit, up to date reviews. I bought my 6 hp 12 gallon Craftsman based on a top rating from a magazine review, but I cannot remember which one. Powerful and quiet, under $100. What more do you need?

[roger wiegand]

Very happy with my new Bosch VAC090S. Head and shoulders better than the ShopVac and Sears machines that preceded it. It can roll over its own cord without falling over! I only buy a new one every 15 years or so, so I can't give you any real comparisons, nor have I measured or worry about absolute performance numbers. The current machine is relatively quiet, provides HEPA filtration, and does everything I ask of it (unlike the prior machines). I still have the ShopVac for wet use. I don't know or care how many alleged horsepower each of them has.

[Joe Jensen]

Yes on the Alleged HP That hasn't come up but the HP numbers are really meaningless. CFM and suction are the things one would want to compare but they all seem pretty comparable. The bigger difference in my experience is how loud they are. my WAP is like 56 db which I can't hear over a small random orbit sander. Most better vacs are around 72-76 db. a 3 db difference is barely noticeable, a 10 db difference is twice as loud. With my 1980s era Sears vac I had to wear hearing protection even to clean up the shop. With the 2010 era Rigid there is no need for protection, not even bothersome. With the WAP the Radio in my shop is louder.

[Mike Henderson]

Full load of a 1 hp motor is about 16 amps, While not a 1/4 hp, it's more like a 1/2 hp who's full load is 9.8 amps.
Either way, they still overstate the horsepower by calling it peak horsepower which is achieved for a fraction of a second and is not sustained while in use.

You don't specify whether that's a 120V motor or a 240V motor. Let's assume it's 120V. 16 amps at 120V would be almost 2,000 watts. And we know that one HP is 746 watts. So if your motor is really supplying 1 HP at 16 amps at 120V, your motor is only about 39 percent efficient. [Side note: 746 watts at 120 V requires a bit over 6 amps.]

Electric motors are pretty efficient at full load, usually above 80%. Large electric motors are all over 90% efficient. I've never heard of one that is only 39% efficient. Also, almost all of the lost energy (61%) would be converted to heat, so that motor would get pretty hot. (for the electrical engineers reading this, the power factor at full load is close to 1. At less than full load the power factor will be quite a bit less than 1, which is why you don't see the current increase proportionally as the motor loads up).

Perhaps you mean that a 1 HP motor may draw 16 amps at startup.

Mike

[Tim Bridge]

Mike, since I am a master electrician I tend to get my info from the National Electric Code.
They have tables that are used for the calculations of full loads for motors.
I was using the 115 volt single phase columns for my amperage.
I am not sure where they get their numbers from, or the efficiency they use.

From my experience with the motors that I have wired and trouble shot, their numbers are close to the nameplate ratings on the motors that are used in commercial and industrial applications.

Edit: I just started compare the NEC chart for single phase motors and some motors on the Baldor website, I see some motors are inline with the chart and some are way off. I am going to look at this closer.

[Mike Henderson]

Mike, since I am a master electrician I tend to get my info from the National Electric Code.
They have tables that are used for the calculations of full loads for motors.
I was using the 115 volt single phase columns for my amperage.
I am not sure where they get their numbers from, or the efficiency they use.

From my experience with the motors that I have wired and trouble shot, their numbers are close to the nameplate ratings on the motors that are used in commercial and industrial applications.

Those numbers don't make sense, Tim. Check the mathematics I gave you in my previous post. It's clear that a 1HP, 120V motor should not draw 16 amps at full load.

A 1 HP, 120V motor operating at 80% efficiency would draw about 7.8 amps. At 70% efficiency it would be about 8.9 amps. Electric motors, even small ones, are generally at least 70% efficient. We know that electric motors are more efficient than 40%. The problem with very low efficiency would be heat. All those excess amps would turn into heat. So if the motor was drawing 16 amps, while only needing 6.5 amps to produce 1 HP, those other almost 10 amps would be heating the motor. 9.5 amps times 115V is a bit over 1,000 watts. That's a lot of heat for a motor the physical size of a 1 HP motor to dissipate.

The motor in a shop vac gets cooled by the air flow but you'd feel the exhaust air to be pretty warm. 1,000 watts are essentially a blow dryer. And that amount of heat generated inside the motor would really affect the life of the motor. Blow dryers use resistance elements to generate that much heat.

Mike

[Energy is conserved. A 1 HP motor puts out 746 watts of mechanical power, by definition. Any additional power input to the motor turns into heat. A motor is a device to turn electrical energy into mechanical energy. A generator is a device to turn mechanical energy into electrical energy.]

[Joe Jensen]

The motor also has to dissipate heat at full load amps in order to be rated at a HP level "continuous duty" The ridiculous ratings on small tools is "rational" because they ignore the heat dissipation, and they consider the rotating mass too, so it's kinetic energy plus the max current you can draw before tripping a breaker.


Also for giggles, put your 6.0HP shop vac on a circuit, and also a sander. Both will run without tripping a breaker so that 6.0HP is drawing less than 120V times 15A or less than 1800 Watts.

I can't believe that the Feds who love to regulate everything let companies use BS ratings like this that only serve to mislead consumers. The power of political donations I suppose.

[David L Morse]

Mike, since I am a master electrician I tend to get my info from the National Electric Code.
They have tables that are used for the calculations of full loads for motors.

Those numbers don't make sense

Mike's right, from the point of view of an end user who needs to know the actual current usage.

Tim's right, from the point of view of someone who has to make a safe wiring installation.

Those tables are used for determining the required ampacity of circuits supplying power to motors. An induction motor can apply a lot more stress to wiring than would be indicated by it's full load rating. The numbers in that table are larger than rated FLA to force a larger wire gauge to safely tolerate that stress.

BUT, shop vacs don't use induction motors. Like routers and most other hand held power tools they use universal motors. Those two types of motors have different operating characteristics as well as a different set of rules for labeling. Those rules (actually the lack thereof) helps account for the bogus HP claims on both shop vacs and routers.

[Curt Harms]

but, shop vacs don't use induction motors. Like routers and most other hand held power tools they use universal motors. Those two types of motors have different operating characteristics as well as a different set of rules for labeling. Those rules (actually the lack thereof) helps account for the bogus HP claims on both shop vacs and routers.

I was wonder if someone would bring this up. From what I recall - can't cite data offhand - universal motors are less efficient than induction motors but they're smaller, lighter and turn faster than induction motors. All desirable traits for a shop vac.

[Jim Dwight]

I googled shop vacuum reviews and found ones by Woodworkers Journal, Popular Mechinics, and Consumers reports. I only looked at the Woodworkers Journal one and it was mediocre. Basically they liked everything. but it did summarize features.

I use a Rigid on a cart with a dust deputy, quasi HEPA filter, and auto on switch. It works for me. The filter keeps me from blowing fine dust all over. The cyclone prevents frequent filter cleaning and makes the size of the shop vac dust compartment irrevalent (nothing goes there). The auto on is for use with sanders and other tools. If I need it to slow down, I use a router speen control.

[Mike Henderson]

I was wonder if someone would bring this up. From what I recall - can't cite data offhand - universal motors are less efficient than induction motors but they're smaller, lighter and turn faster than induction motors. All desirable traits for a shop vac.

Yes, you're right about the efficiency. In doing my calculations, I was thinking of induction motors.

It's clear that tools using universal motors have fake HP ratings. For example, a 2.25HP router would output about 1,678 watts of mechanical energy. The input power is listed at 115V at 12 amps, which is only 1,380 watts. So if it really put out 2.25 HP, the efficiency would be over 100%.

I wonder what the real HP rating of a router would be.

Mike