DC shuts off on its own

[Ben Grunow]

My 2 year old Dust Gorilla has started shutting off on its own and I am almost positive that it is not due to motor overheating. It happens when all ducts are closed, motor never feels hot and there is an audible "clunk" from the switch (which is factory and has a remote key fob setup) like when you press the red button to turn it off. The unit will run for about 3-5 minutes before it turns off. I dont think it is intereference from the neighbors garage door either because it happens all the time and at all hours. It sure does make me nuts though.

Anyone have any idea what I should do? Is the switch just bad or can it be diagnosed and repaired?

Little help would be great.

Thx

[David Christopher]

Ben, the first thing I would do would be call onieda and see if their tech guys could lead you in the right direction

[george wilson]

You aren't supposed to have ALL the ducts closed. It might be overheating the heater coil in the switch,shutting it off. Always have a gate or 2 open.

My 2 hp Dust Gorilla cannot be turned on more than 3 or 4 times in an hour,or it shuts off. I generally use it in short sessions,and the motor doesn't get time to cool off from starting up.

[Matt Meiser]

Why would you run it for 3-5 minutes with the ducts closed anyway?

But with ducts closed, that should be the lowest load on the motor--no air to move. The moving air doesn't cool the motor, like a shop vac. Highest current draw is with a blower with no ducts because its moving the most air. Or am I wrong in understanding all the measurements that people were doing 6-7 years ago when the cyclone craze hit?

First place I'd check is the RF remote. Either interference or failure of some sort. Can you bypass the RF part or is it integral?

[george wilson]

Matt,that's exactly backwards. The impeller is trying to pull a vacuum in the ducts,which is the HARDEST work. Oneida will tell you to always start up with at least 1 gate open. Those instructions are in my gorilla manual.

[Phil Thien]

Matt,that's exactly backwards. The impeller is trying to pull a vacuum in the ducts,which is the HARDEST work. Oneida will tell you to always start up with at least 1 gate open. Those instructions are in my gorilla manual.

Actually, Matt has it right.

Not sure why they insist on one gate being open. It might have something to do with the type of impeller they're using.

Or perhaps they're worried the people using very lightweight ductwork may see a collapse if they don't have a gate open.

[george wilson]

I don't think you are right,Phil. It doesn't make sense that the impeller would not be working hard trying to pull a vacuum. If it isn't,why would there be fear of sucking ductwork flat? Yes,cheap ducts can collapse. Anyway,I'm leaving 1 open,and I suggest the original poster try leaving 1 open and see if it works. Something is over working the motor,or possibly the heater coil is bad in the switch.

[Charlie Plesums]

As an electrical engineer, I am betting on Matt being right.

If a motor is working hard, does it go faster or slower? When it is straining under a load, it slows down. Put your hand over the end of the hose on a shop vac and see if it goes faster (higher pitch sound) or slower (lower pitch). Seems like it would be working harder, but it is "just spinning the tires" and not moving any air. Then let the air flow, and you will hear it slow down as it works harder.

[Alan Schwabacher]

Matt, Phil and Charlie are right. It's not that the impeller is doing no work at all when all blast gates are closed, it's doing less work than when they are open. The work it does is whacking air molecules around, and when gates are closed there's less air going by. Yes it has taken some work to lower the pressure, but low pressure air has less stuff to push against. If you put the entire impeller in a vacuum chamber and pumped out all the air, then the impeller would do no work.

Or think of it this way. What if you were to try to get power out of the moving air with a windmill? The more air you had moving, and the faster it went, the more power you'd get. The more you close the blast gates, the less moving air you'd get.

You can measure this yourself with an ammeter. If you measure the current draw of a DC while open to airflow, it will draw significantly more current than if you close all the blast gates.

[Ken Fitzgerald]

I just read the checkout for my Oneida DC.

It has you measure the maximum current with all the blast gates open and insure it doesn't exceed the recommended maximum current draw.

It also warns you to NOT turn it on during installation without ductwork connected or you could burn up the motor.

[Paul Atkins]

Totally cover the output and see how much load there is - well don't do that, but there would be more air being compressed and thicker. If it pulled a total vacuum with all intakes closed there would be no air to push -less resistance. The collapsing ducts are due to the outside pressure pushing in against less air pressure. Would a vacuum press work in space? No.

[Cody Colston]

With all ducts closed, the DC impeller removes the air until there is virtually none left to remove (although it will never achieve a total vacuum). With no air to remove, the impeller is basically freewheeling with no load.

I have a 2hp Commercial Oneida Cyclone and I can tell by listening when all the gates are closed because it makes a "thumping" sound. I attribute it to air coming back past the impeller to fill the vacuum behind it which is then removed again, which then returns, which is then removed...thus the thumping...sounds good, anyway.

I have no idea what's causing your DC to switch off but it appears the solution is as simple as leaving at least one gate open...which you should do, anyway.

[Rob Wright]

First thing that comes to mind - Is your filter plugged? I also have a 2 HP super Gorilla and had this happen a few weeks ago. I was cutting a lot of MDF on my cnc and had let the bin get a little too full. I ended up taking the filter outside and blowing compressed from the outside to clean it. I have not had the problem since I re-installed.

[Chip Lindley]

I'm no DC expert! I just use one! But, why would a motor pulling NO LOAD be in danger of burning up? What is overloading the motor? Somebody Show Me! (I'm from Missouri!)

Vacuum pumps work HARD to evacuate *almost* all atmosphere from an enclosed area. The less atmosphere, the harder they work, until a serious *vacuum* is achieved! Is this NOT what a DC blower is trying to do? Would not a DC motor work just as hard, trying to pull a vacuum? Rather than at its rated CFM through a ductwork system?? ...hmmm....

As for the OP's shut down problem, there is an adjustment on most motor starter heaters for min. and max amperage. Perhaps yours is set at minimum. All heaters are a bit different. Some trip more easily than others at the same amp. setting.

[Wes Grass]

'Pressure' is a factor with a positive displacement pump. Block the output and the current goes up.

These don't generate pressure (primarily), they generate *flow*. Current is related to the mass of air moving through the system. Block the inlet, or the outlet, and the flow stops. All that's left is stirring around the air inside the blower housing.