Hopper level sensor/switch question for stokers

Since I'm contemplating adding an auger feed system to my Coal Gun's feed hopper, and the AHS supplied augering unit is rather expensive, can anyone recommend an economical hopper level sensor that would switch on the auger motor when the coal level in the stoking hopper is low and switch it off when the coal level in the hopper is adequate?

Given that you still have to deal with ashes and that you presumably would still want to regularly check the stoker you could just operate the auger with a manual switch.

I think was discussed a while back, do a search on HOPPER LEVEL SENSOR, or something like that. A lot of different ideas.

I believe I've narrowed this down to a type of sensor/switch known as a "Capacitive Proximity Sensor" or "Capacitive Proximity Switch". They come in normally open and normally closed switch configurations. I assume the normally closed type would be the one to choose.

Perhaps it would be best to use two of the sensors? One to turn the auger motor on at the hoppers lowest desired fill level, and another to turn the auger motor off at the hoppers highest desired fill level.

Or alternately a single level sensor to stop the auger motor whenever the coal in the hopper is at the desired high level, and a timer that would delay the auger motor from starting again for 24 hours.

What about making an auger like an axeman anderson, hollow center and the whole auger turns, set it to run slow when the stoker motor does. It doesn't overfill, what's not needed trickles back to the bottom.

AA130FIREMAN wrote:What about making an auger like an axeman anderson, hollow center and the whole auger turns, set it to run slow when the stoker motor does. It doesn't overfill, what's not needed trickles back to the bottom.

I'm trying to fathom how this might work with the AHS and its ovrhead hopper.

Bob wrote:Given that you still have to deal with ashes and that you presumably would still want to regularly check the stoker you could just operate the auger with a manual switch.

Excellent point. If the ash tub requires attention before the hopper, it makes sense to just operate the auger with a manual switch. I am a big fan of "K.I.S.S." design.

Rob R. wrote:

Bob wrote:Given that you still have to deal with ashes and that you presumably would still want to regularly check the stoker you could just operate the auger with a manual switch.

Excellent point. If the ash tub requires attention before the hopper, it makes sense to just operate the auger with a manual switch. I am a big fan of "K.I.S.S." design.

I agree that would be both the most economical and simple solution to the problem, as well as being a practical solution as well, but the level sensors can be found in the range of $70 to $100.

Anything automatic, electronicly sensing, can and will go bad eventually, and you will either have an out fire due to no coal, or coal overflowing onto the floor around the boiler.

Bob, and Rob R. have the right idea. Since EVEN WITH a handfull of $70-$100 sensors and relays you will STILL have to [out of curiosity] look in the hopper to see that the sensors and relays are doing the job... just put a simple toggle switch on the auger, and let it work while you empty the ash pans.

It's not as if you have a one day hopper and a 5 day ashpan.. you will still need to look in on the boiler as frequently as you do now [ashpan limits, not coal supply limits]..

K.I.S.S. is the way to go.

Greg L

LsFarm wrote: just put a simple toggle switch on the auger, and let it work while you empty the ash pans.
Greg L

If I might add a twinge of wisdom from my own experiences -- you might want some kind of failsafe timer to switch off the auger after a predetermined time, just in case you forget to manually flip the toggle after emptying the ashes.

I had a switch to turn off the blowers while I emptied the ashes. On two occasions I got distracted by something (kids, phone, dog, life, who knows...I can't remember) and I forgot to switch the blowers back on and the fire went out.

Now my setup stops the blowers for 3 minutes, or until I press the "resume" button, whichever comes first.

I vote for the toggle switch or maybe a limit switch with an arm attachment. Proximity switches probably won't work reliably in the environment that you are going to be using it. Coal isn't a great conductor so it will take a fairly sensitive large diameter switch to even have a chance at working. Also as the end of the switch gets dirty from the coal fines it sensing distance will become greatly impaired and may lead to overfilling the hopper or jamming of the auger.

For a simple switch with a fail safe shut off and economical to to purchase...use a "spring wound" switch...commonly used for bathroom exhaust fans, etc.

Still qualifies for the K.I.S.S. principal and is "goof-proof" too.

Spring Wound Switch

McGiever wrote:For a simple switch with a fail safe shut off and economical to to purchase...use a "spring wound" switch...commonly used for bathroom exhaust fans, etc.

Still qualifies for the K.I.S.S. principal and is "goof-proof" too.

Spring Wound Switch

That's a great idea. Once you know from experience roughly how many minutes it takes to fill the hopper from a given starting level, you can peak into the hopper before hand, close the lid, and then dial the timer to the number of minutes desired minus some safety margin, and it will happily run the auger only until it times out.

Here is one that will run for only up to a maximum of 5 minutes, and will handle a 1 HP motor. http://www.smarthome.com/25074/Intermatic-FD5MW-5-Minute-Spring-Wound-Timer/p.aspx

Sounds like a super idea to me!