Coal-Trol thermostat

PostBy: pvolcko On: Fri Jan 27, 2006 1:53 am

madrmc, you are correct. If your stoker mechanism has only one motor then setting the triburn setting to "Y" is meant for your situation. The feeder will run all the time and it will change speed as needed to maintain the setpoint temperature.

We use this mode on a Reading triburn stove here in the shop with very good results and have tested it on a number of other 1-motor feeder stoves. They can be a bit more tricky to get adjusted than the non-triburn stoves, but we get good range of control on them once setup properly.

Neil would be better able to answer your concern about the impact on the motor in tri-burn mode, however my first impression is that it is a trade off, and a small one at that. It may be running all the time, but it is running at reduced speed so on average total motor turns is going to be about the same as with a traditional on/off controller. Also, by running all the time some things are avoided, like the cumulative effect of startup heating when the stoker arm is at the higher torque segments of the stoker arm's motion. Of course, there are benefits to starting and stopping, including the potential for greater control of the feed rate. A motor, especially one under load, can only be slowed down so much before it will stop turning entirely.

That all said, some have opted to run coal-trol in non-triburn mode on 1-motor stoker stoves and furnaces. While this is an option we don't actively recommend it. Those wishing to try it can and if they call us we'll ofter what help we can in setting it up. If they're close by we've even been known to make a house call. :)

Lastly, stoker range of motion. This is determined entirely by the stoker adjustment screw and stoker mechanics. All the coal-trol (in either mode) or any on/off controller does is control how many cycles are done in a given period of time.


Paul Volcko
Engineer
Coal-Trol Digital http://www.automationcorrect.com
pvolcko
 

oops...

PostBy: pvolcko On: Fri Jan 27, 2006 5:35 pm

I'm sorry, I have made a mistake in my description of the tri-burn mode. I had forgotten that we employ a hybrid of the speed control and the time-proportion methods of feed rate control in the tri-burn mode. This means that when a feed rate is called for that would force the motor to operate below the minimum speed needed to safely keep it running we start using the time-proportion method.

This affords us a much wider range of feed rate control than if we only went as low as the minimum motor speed.

I'll leave Neil to respond any further on the motor life issue. It is a bit out of my range of knowledge and experience. However knowing that we do time-proportion on the lower side of the feed rate range, which means we run the motor fewer rotations than if we were running at the minimum speed all the time, may address your concern.

So, I'm going to be quiet now before I dig too big of a hole. :)

Seriously though, I apologize for the mistake. I knew something didn't sound quite right when I was writting the prior post.


Paul Volcko
Engineer
Coal-Trol Digital http://www.automationcorrect.com
pvolcko
 

PostBy: madrmc On: Sat Jan 28, 2006 4:11 pm

Paul, thanks for your response. I have some more questions as I'm brainstorming. I guess I thought it would be a good idea to ask them in the forum in case anyone else is interested.

Is the coal-trol just an efficient thermostat or does it increase the efficiency of the stoker in other ways?

Do you have the various stokers on site, or some other type of partnership? (From what I understand the stoker manufactures may have tested it on their own, but I haven't seen anything that summarizes their findings). If you're not currently testing and tweaking your product in cooperation with the manufactures can you tell us if that being discussed?

Have you found the continuous feed or the on/off feed to be more efficient. (I know you said the continuous changes to on/off at slow feed rates)

Have you found the varying speed of the convection blower to increase efficiency? Some members of this forum have had better results keeping the blower speed low (to maximize air temp) and circulating this warmer air with fans. It would seem for the thermostat to work as good as it could the heat produced from the stoker would need to be put in the room as soon as possible. Otherwise, you might overshoot on the temperature side.

Are you testing whether varying the rate of the combustion fan increases efficiency. I think it was implied that the combustion fan on the current model doesn't vary, but that it might on future models. A slower fan on lower feed rates would seem to keep steadier temperatures and avoid the potential to burn out on lower settings.

Matt
madrmc
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing III

PostBy: pvolcko On: Sun Jan 29, 2006 6:53 am

Is the coal-trol just an efficient thermostat or does it increase the efficiency of the stoker in other ways?

Coal-Trol makes no modifications to the stoker mechanism in any way. The efficiency increases are mostly the result of our control being able to dynamically adjust the feed rate.

Do you have the various stokers on site, or some other type of partnership?

We have three stoker stoves on site: one Reading, one Leisure Line, and one Keystoker. We also have access to two alaska stoves through partners and friends of the company who serve as in-home testbeds (they've been running coal-trol in various forms for the last 2-3 years). There is a mix of 2-motor and 1-motor stoker mechanisms.

(From what I understand the stoker manufactures may have tested it on their own, but I haven't seen anything that summarizes their findings). If you're not currently testing and tweaking your product in cooperation with the manufactures can you tell us if that being discussed?

Since we started selling Coal-Trol we've been in frequent contact with stove makers (and dealers and others) and many have evaluated it. If you're interested in their impressions and findings we encourage you to contact them. Also we are currently working on next season's product offerings with input from manufacturers, individual customers, our in-home testers, and our own ideas. For now we aren't discussing details publicly, but in the coming months we will be making a 2006-2007 product line announcement and updating the website.

Have you found the continuous feed or the on/off feed to be more efficient.

We have not carried out comparitive testing like that, and I kind of doubt we ever will. I could explain the testing methodology and math that leads me to say this (feel free to PM if you want to discuss it), but suffice it to say that in the end what the test will end up determining is that the Coal-Trol and it's two modes will not play into the efficiency differences observed. What will be determined is the relative efficiency of one stove to another or one stoker mechanism to another. As a company we want to do business with all stove/stoker makers and will not step on toes by doing such a test or releasing such findings. What we are interested in is the relative fuel use people see between using their old control methods and using the coal-trol (regardless of stove/stoker type) and those are tests we're doing and intend to release results on. Anectodal evidence so far indicates that the fuel savings estimate of 11% is pretty conservative.

Have you found the varying speed of the convection blower to increase efficiency?

Increased air circulation in the space being heated is always good for fuel use efficiency. So to is making sure the thermostat isn't in the radiant heat area of the stove or in a hot air plume, such as in the path of air from the convection blower. That said, our varying the speed is because of the comfort factor you bring up. Blowing on high speed when there is a lower fire means that the air coming out will be relatively cool, so we dial up varying amounts of fan speed for different feed rates in an effort to keep that convection air relatively warm.

Are you testing whether varying the rate of the combustion fan increases efficiency. I think it was implied that the combustion fan on the current model doesn't vary, but that it might on future models. A slower fan on lower feed rates would seem to keep steadier temperatures and avoid the potential to burn out on lower settings.

You're correct we do not currently vary the combustion speed directly, and it is a possiblity it will show up on some future model. However, do not assume it will be on the next model. :)

We know there are efficiency gains to be had through control of the combustion air, the burn area, and other parts of the stove, but it becomes a question of diminishing returns and prioritizing all the different feature ideas and balancing that against time pressures and product cost. We're a small company just starting out, we need to pace ourselves. :)
pvolcko
 

PostBy: Richard S. On: Tue Oct 03, 2006 9:25 am

I'm going to lock this due to the age.
Richard S.
 
Stoker Coal Boiler: Van Wert VA1200
Coal Size/Type: Buckwheat/Anthracite