Pictures of your stove

Highlander wrote:Hello fellow Coalburners
It is the same PLC, a Crouzet M2, that I used with the first Harman stove, but the program has grown substantially and includes reset control, proportional / integral control mode, a coal useage counter, a reverse anticipator fucntion, and a scrollable display for water temp, outside temp, manual control mode, Summer / Winter mode and a coal useage counter. The PLC can read 0-10V signals with 8 bits of precision, not great by todays standards, but plenty for this level of process control.

I have a fairly decent background in PLCs with PID control and analog I/O, mostly Allen-Bradley SLC and some DeviceNet. You've pretty much done what I've been thinking about all along - integrate modern controls with old-tech coal burning to bring it into the 21st Century. That is a really impressive setup and very well thought out. I was thinking about using a Cubloc PLC and doing something a bit similar on my Keystoker next year.

During the summer months I burned about 12# per day for hot water. I estimate using between 4 and 5 tons for the year. With propane at $3 / gallon, it should have payback in 2 years for an investment of about $5000. Not too shabby.

How much heat does the boiler add to the house? Is the house air-conditioned? Is the boiler room separate, insulated, and/or ventilated from the rest of the house? I'd be concerned about the residual heat from the boiler idling with no hot water demand most of the day adding a lot of heat to the house that must then be removed via the A/C system, especially in a modern, well insulated home. I imagine in a old home with damp, fieldstone basement or similar, that added warmth would be welcome in the summer, but in a modern home, I'm not so sure.

coalkirk wrote:.. I also noted that the restrictor plate had been removed. I would like to do the same thing with outside air but I am reluctant to remove the restrictor plate...

Without the speed controller and idle mode he has built into the combustion fan circuit you can't remove the plate (IMO).

Highlander wrote: Ive added an outside air supply to the combustion blower and a speed control to the blower motor. When stoking the blower runs full tilt, but then cuts back to an idle speed that helps keep a larger fire bed in times of low demand.

Yanche, thank you for your kind words. I would hope that some of the manufacturers out there would rethink their current designs and put some more sophisticated controls into their coal burning products. Harman does this with their line of pellet fired equipment, yet the coal fired stoves and boiler, get the 1980's electronic timer control.

Chris, the PLC I used is one that my company distributes so the choice was fairly easy. There are a multitude of controls on the market that could do the job, their ability to process analog signals is the key. As to my house, the boiler is located in the basement and provides a welcome amount of additional heat there in the winter. In the summer, it gets pretty warm so I open a screen door to let some of the excess heat out. We normally don't run AC in the summer, just an attic fan, but it does add to the heat. I've added insulation under the sheet metal to help with the heat loss, it adds maybe 5 to 10 deg to the average boiler water temperature. All in all a small price to pay for the greatly reduced propane bill.

Kirk, The flex hose with the outside air is a relatively recent addition, I didn't have it during the summer months. I ran with the restrictor plate, maybe half open with the combustion blower running all the time. My chimney draft was about .02" with outdoor temps in the 80's, but I never had coal gas. I did experiment with it open all the way and still had no coal gas smell. The chimney is a double wall insulated SS type. It draws very well in the winter, almost too well, the baro damper swings open quite a bit, but its doing its job. The latest mod was the variable speed control for the combustion blower. When the stoker runs, the blower runs full tilt, when its off, the blower slows down to less than half speed. This should keep a larger bed of coals and reduce the excess air flushing heat out of the boiler while still maintaining the fire during long periods of idle.

This boiler and burning coal has turned into a hobby for me, I look for ways to tweak the operation and controls to maximize the performance and minimize the fuel useage. Some people might think I'm a bit crazy, but I'll bet people here know what I'm talking about.

Bill

i like the idea of the slowing down the combution blower during idle time have you noticed a diffrence in coal usage and stack temp. i have a kaa-2 keystoker boiler and my combution blower runs one speed all the time. i notice at idle my stack temp is 100-150 degrees and at full fire it is 250-300 degrees. do your mumbers relate to mine

i like the idea of the slowing down the combution blower during idle time have you noticed a diffrence in coal usage and stack temp. i have a kaa-2 keystoker boiler and my combution blower runs one speed all the time. i notice at idle my stack temp is 100-150 degrees and at full fire it is 250-300 degrees. do your mumbers relate to mine

Chris

Its hard to tell exactly how much the flue temperature drops when the blower cuts back to idle, I'm sure it does, but I haven't measured it between cycles. My cycle time is 7 minutes or 420 seconds total. The on time varies from a low of 30 seconds to a high of 410 seconds. When it idles for a while, the temp drops dramatically, the fire will burn down to a ribbon across the back, maybe an inch or so wide. The exhaust temp is so cool you can stick your hand in it.

The speed control I used was from Lowes, its meant to control a paddle fan or some other small motor but it works fine with the combustion blower on the Harman. If your blower runs all the time, you would probably need to add a relay that is on when the stoker is on. You could then use the contact to bypass the speed control when the unit stokes, and cut back to the idle speed when its not.

Hope this helps

Bill

thanks for the info i could wire a spdt relay and it would work just fine. i am just wondering if it is worth it . my timer runs evey 10 minutes for 90 second to maintain the fire. if you could can you posiblly check what your stack temps are with the blower running normally and then with the blower running controlled and see what the diffrence is and let me know i would be curious to know.

Very nice, Highlander!

I truly applaud your work Highlander an actual Smart control.

What do estimate the cost of components for the control and sensor array

Thanks again for all the kind words.
Coalstoves, the PLC and temperature transmitter were demo stock, but I would estimate it at less than $300 for the components. The outside air temp sensor was a Velleman electronics kit, cost about $20 online. It didn't have the higer temp range needed to monitor boiler water, but is fine for ambient air temperature.

Chris, I'm on the road now, but I will try and see if I can measure a difference between the full and partial blower temps when I get back.

In my case this will be a pictures of my system. Other photos of this project are in the thread "Better Late than Never" in the Stokers section.

A "brief" discription. As can be seen in my avitar, I have a good size house, and a 40 x 60 workshop out back. When I built the shop building, I put in radiant tubes in the concrete for heat, with the heat source to be determined later. I researched most viable boilers, and various fuels. I finally settled on an AHS Coalgun, S-130. I also have an oil fired boiler in the system (not yet ready for use) that will serve as back-up if the coal fire goes cold, if I'm out of town etc. There's an underground pair of insulated pipes leading to the house for integration to my heating system there. I'm using a Tekmar 2 stage boiler control with outdoor reset, it monitors outdoor temp, coal boiler temp, shop room temp, and a few other attributes. If the system temperature falls below a preset value, (i.e coal fire goes out) the oil boiler will take over and keep things going. I used a Tekmar variable speed mixing controller to mix down the boiler temp to the required temp which is then sent through the shop floor tubes. The shop is on priority, which means even if the house were to call for heat, the house will get none, until the shop is satisfied. I have two additional zone take-offs ready to use as needed. I still have a few details to complete for the oil boiler, and some wiring clean-up to do. I started up the S-130 last weekend, with very little effort. The shop was a COLD 34 when starting, burned about 300# of coal as of today just to warm up the 35 yrds of concrete and all of the items inside the shop. Now up to 62 degrees, which is more than warm enough for me. I will now begin tracking coal usage to maintain the temp of the shop. The house integration is still a few weeks away.

My Crane Coal-cooker, purchased used in 1985 and still going strong.

Anybody know what this is [ha ha] !!

Fairly new to the forum, thought I would post a picture of my stove.



Believe it or not the stove was free. The chimney was not (ouch!).

Very nice tiles you have there SJ. Jim

Second day with the Hannover 1.

When the weather warms up I may repaint it a high temp gray (to match the dust).