The AM Forum

Hola,

Thought I'd post some pics of the latest projects here. I put some large aluminum heat sinks on top and sides of the coal stove. Class E efficiency. I started with a 1/4" plate of aluminum and then added the finned heatsinks. The heatsinks get as hot as the stove and appear to dissipate heat as expected.  This has reduced the temperature of the chimney gases quite a bit as shown by the temp gauge when placed there. This can be done with coal, but not with wood due to creosote build-up with wood. Coal burns clean even at lower chimney temps.

I painted the heatsinks flat black to match the stove.

There is a blower-squirrelcage at the ceiling/wall junction thats moves warm stove air into the shack.

T

While we're at it, here's some shots of the sailing canoe in progress. Homebrewed a new rudder and tiller. The rudder is aluminum sheet and about 40" long - actually bigger than needed for overkill.. The gray plastic pipe is used to raise or lower the rudder from the operating seat. Also some new dagger boards and a mast mounting up front. I sewed up the biggest sail to date and am looking forward to the springtime trials...  

The rudder system still needs to be painted flat black.

T

Did the guy who delivered that thing back into your porch?

And what else is new?  Over the summer I installed a full-blown, monitored, security system. Much of it my own design using store bought stuff. There are four outside perimeter sensor outposts surrounding the house, one pictured -  IR cameras, remote web access to all functions and video, motion detection, etc etc. As a first line of defense I have 26 flood lights that are activated by the outside alarm detectors. At night, if you walk around, it looks like the Bush compound as you trip the various sensors with perimeter lights activating and muted beeping. The house has a separate system loaded with the usual detectors, etc.  I figured the world is getting crazy and more violent, so might as well do it up right.  So far the radio has not triggered any alarms... ;D ;D

And, here's a current pic of Yaz. He always joins me sailing and watched during most of the canoe project. I noticed he sleeps like a log now that he doesn't have to be a security dog all night... ;D

T

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Given your previous experience mixing heat sinks and burning apparatus, do you have a working CO detector in the casa?

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Yep.  The security system itself has CO, smoke, basement water and even pipe freezing detectors set up. They are checked by the panel daily and if activated, is part the the monitoring center's information.  I also installed a stand-alone CO unit above the stove just to be redundant. So far it stays on zero when the coal stove is running.

Steve, I'd take you up on the Area 51 sign, but it might keep the UPS guy from stopping by ... ;)


Dave, that security sign is planted exactly where that crazy guy from NJ backed into the house.


T

Yaz is quite a sheet metal worker.

when are you going to  put some blades on those boats and do some ice sailing?

So you didn't fix the damage and decided to cover it up with a sign.

Excellent.

Ever consider running for office?

Is it possible to install about 500 12 gauge shot guns that can spot and kill only guilty people automatically?

Please let me know the manufacture of your stove. I need to get away from wood use at the camp because I don't have time to deal with it. I can buy coal in the Albany are by the ton in 40 pound bags. Price unknown. They talk about using rice coal at this establishment. I know a lot about hard coal since I'm from the coal region on N.E.
PA.

Neat idea with the heat sinks. I would like to attach to the back a open tank for hot water up there. No pipes to worry about and no pressure related worries. 

Hi Terry,

I found the stove on Craig's list. It's a Harmon III, the 2nd biggest coal stove they make, good for about 95K BTU.  They are not common, but I found one in a week. It weighs 500 pounds and is super heavy quality. Forget the crap at Home Depot and all that. Many high-end stove stores sell these new for about $2K. You can get one a few years old for about $900 or less.

The thing I like about it, especially being a coal stove - this is amazing - is that when the temp outside reached 60F last week, I was still able to keep it idling low and it stayed lite continuosly. Normally my wood stove would lose draft and go out or just run too hot.  There is total heat control by using the air inlet. The stove has run 24/7 for about 10 days now. I use coal slightly smaller than golf balls.

Lately the stove has been running OVER 24 hours without touching it at all. I think it wud easily go for 36 hours when the temp is above 30 degrees. I load it up with 40 pounds of coal and some nights even more. My old coal wood/stove was dismal in comparison. A dedicated coal stove is the key.

I do have a large pail of water that sits on it for humidity into the air, but that's it.

I've been monitoring the exit stove pipe carefully and still find it to be slightly uncomfortable to the touch with the main stove running at 500 degrees today. This is definately due to the heat sinking robbing the last heat from the gas. Again, when I tried this with the wood stove last year, the draft died and creosote became a problem. Right now I can look at the chimney outlet and see NO sign that the stove is on. It runs that clean.  The coal turns to ash. I have two pails filled with ash and there is no coal, just white powder. Who could axe for more?   ;D

The oil heat has been off for 10 days now and the temp has been down below 30F in the wee hours lately. The upstairs stays warm all night as well as the first floor. The cellar is cold, but that's the breaks...  I will have to do something about that - at least monitor it in case of pipes freezing down there.

T

Good info Tom, My grandparents and just about everyone in the early 1900's used a small stove in the cellar know as a "Johnie Stove" (There are many ways to spell it and I'm not sure)

 Well anyhow these were used to heat water when the main furnace was off and some people used them all the time because early coal furnace's were hot air where a big grate was in the living room where the heat came up and rooms upstairs were heated by vents in the ceiling. There was  a thing in the upstairs rooms called registers. You could open and close the vent on them to leave heat in. Trust me, those rooms were cold but grandma's love kept you warm with her home made quilts.

I guess where I'm going here is that you could if you have the space, put a very small coal stove in your basement to provide heat. NE1S has a nice one in his basement and it works fine.

Class E stove.. The heatsinks are a great idea and you could probably put many more on it and increase the efficiency even more. Have you condidered how to recover heat from the flue?

Pat,

I'm about out of heatsinks right now.. ;)  Though the exit temperature is probably down to as low as it should run due to the need for it to maintain a draft in the chimney. As you know, some heat is needed to rise up the chimney or the flow will stop and the stove will go out. That said, I'll bet a good way to recover the last bit of heat would be to use some kind of heat absorbing/transfer device at the TOP of the chimney as it exits into the air. Though, there is more heat loss as it goes up the stone chimney, so maybe not worthwhile by the time the gases get up there.

The good thang is coal burns at about 2000F, which give us a big delta of temp to work with and still have just enuff to maintain a draft. With a WOOD stove, I'll bet most designs already have enough heatsinking as designed, and by adding more just retards the draft flow into creosote buildup and poor draft performance.

In the past, I got tired of feeding the wood stove. Last night I added about 60 pounds to the coal stove and will try for a record today to break 36 hours unatteneded. We'll see..

T

It's possible to calculate the optimum flue temperature for a given situation.  I remember a hunting camp where they had taken tin cans, cut them to make fins and slipped them over the stove pipe to help capture more heat from the stack.  kinda like those clip on transistor fins.  Not sure how effective that was, but is sure made it look err, interesting.

Natural (not forced) convection heatsinks are dramatically more efficient with the fins running in the vertical position, so that the heat can "slide" up the chimney.

Speaking of which the flow over those fins can be increased more by utilizing the chimney effect...

The heatsinks you have now do serve to increase the effective surface area, but are probably no better than 25% of their capacity, the side ones are almost useless... compared to the ones in the middle... and they are no better than maybe 35-40% or less of their capacity, imo. (guesstimating).

Now if you blow air across them, that changes...

                     _-_-bear

PS. so what does a 40lb burn cost (the per day cost)?

PPS. and what about "coal tar" forming??

One would think the black body heat radiation from a near red hot pipe would be more than the same pipe but cooler. being covered with heat sinks.

(I never got along with my college physics teacher)

More high-energy photons come from a hot pipe, as it was..

Like heat cycle engines, the hotter you can run them, the better.

Until you get a flue fire.

If the heatsinks were closed on the sides and one end was attached to a short up-facing vent duct, the heat would rise from the vent and cool air would be freely drawn (pushed) into the exchange area and pass across the fins. No fan needed. Would that be more efficient?

Cost for coal per day?

Depending on how you buy it, a 40 pound load will cost about $4.50 each at most. So that's about $135 per month, and probably less because I have been getting more like 36 hours per load. But when the temp drops into the teens it will even out.

So compare that with a $500 bill for heating oil every month in the colder months. I understand coal is the best deal going if you have to buy your fuel, that is.  I also have a cord of wood that I use as kindling and use when I need some fast heat.

The sideways heat sinks you see on the top ends had to be placed that way cuz the underside had mini fins, so it would not sit flat. A milling machine wud fix that.

I am evaluating the system simply by the temperature of the exit stove pipe. Today I was running the stove at 400 degrees and could fry spit on the middle heat sinks. They were very hot. However, I could hold my hand on the exit stove pipe without discomfort. That stove pipe used to run much hotter to the point of heating up the bricks through the wall. The heatsinks seem to have helped a lot. It's no surprise cuz it worked with my old wood stove, but the draft died with creosote as I said..

I found another heatsink today and added it to the left side. The sides seem to have a lot of heat. More than I would expect compared to the top.  

The stove does have a fan that blows air through the body. The exit air is HOT - too hot to hold the hand there. I might try blowing a fan through the heatsinks when it gets colder. The fact that they are very hot shows they need some air too.

Interesting experiment indeed.
T

Now about the heatsink placement...  Bear are you saying I should stand the heatsinks up on end?  The problem I found with that is they did not couple much heat in from the top stove steel plate. The air transfer was dismal. When they sit flat with their plenums against the top plate, they conduct heat into themselves bigtime.  So maybe in this case a fan blowing air thru the fins is the best way.

Pat, I think I understand what you were saying - is it about like I just described?


BTW, Bear - good War of the Worlds, Mercury Theater spoof...   ;D

T

Tsk, tsk, Mr. Voo... Burning coal in this age of climate change!  :)

We get ours delivered in bulk, 2 1/2 tons down the chute into the coal bin each season.

-'1S

I have a "commercial" security system that went dead about two weeks after the warranty expired and two months after the company that installed it went belly-up, so I'd appreciate your advice on how to fix it.

It's a "plain vanilla" setup:

• Electronics box in the cellar
• Loudspeaker in the attic for the siren
• 12v battery backup
• Keypad next to my rear door
• Magnetic switches on doors
• Motion detectors in the various rooms

It's all closed-loop, McCulloch-era technology. It's just a local alarm, with no hookup to a central station.

So, what are my options for replacing the alarm box in the cellar?

TIA.

Bill, W1AC

I liked stove coal size the best for long periods between fills. Bigger air gaps between chunks so there is better air flow.  Pea Coal choked itself out too easily.  Pea coal sucked in my stove.
Tom you want to adjust the stove so there is no excess heat going up the stack with the house at a good temp. Also you want a cO detector near the floor if you choke it back too far.
Sounds like you are close.
WHAT A Super Solar DAY!!! about 85 in here and we are pumping warm air into the storage mass.

Bill/ W1AC -

I would get the manual over the web and see what you can do. Did the installer give you the panel codes? If not, you have a problem. If so, try to troubleshoot it. You could always buy a new panel and go from there in case it's bad or you don't have the installer servicing code for this panel.

Other than that, check out FrontPoint Security on the web. They have a cellular based monitored system (Simon XT) that is about $30 per month. You install it yourself and they will program it over the cellular wireless. Depending on the options, you can pay no money upfront or add more features and pay a little. They give you the servicing codes too.

I opted to hardwire my entire house. (doors, all windows, floor sensor, motion detectors, smoke, CO, etc)  I also have web based video and cell phone auto-calls for perimeter breaches or house entry. You cud do the same if desired.


Frank -

OK on the larger-sized stove coal. Yes, I like that idea of have bigger air gaps too. I will stick with it. I tried for 36 hours last night and it JUST made it. 24 hours is a better time span before shake-down and reloading.

CO det NEAR the floor? Please explain??

T

Bill, If you haven't yet, try checking the power transformer that is plugged in a wall socket somewhere close to the alarm box. They sometimes look like a door bell transformer instead of a normal molded plastic wall wart. They supply low voltage AC to the alarm box and a rectifier board in the box makes DC for the system. Check to see if you have any juce at the transformer output.

If you have keys to the panel you can check the backup battery and see if you have voltage from the transformer all the way to the box. Some simple checks might save a bunch of money.

As for the back up power issue, try to decide what comforts you need and what you can do without in a prolonged outage. Add up the wattage than add another 50% or so for good measure. You don't want the generator running at max for long.

I think so. My reasoning with horizontal-flow oriented heat sinks was that the arrangement would benefit from something that would force air to pass within the vanes and spend some time in contact with them, and why not use convection?  In some old in-wall gas heaters the burning chamber is enclosed on all sides except top and bottom by what is basically a 'tube' that lets air convect up between the fire wall and the outer case. Some of them have even 2 layers of this if intended to be mounted in a wall. The cool air is drawn in at the bottom and exits the top. They don't have heatsink fins, but that would cost $$..

Pretty cool idea, Pat.   I can see how the cool air would be naturally drawn upwards thru the sinks using the chimney effect , especially with pic #1.


Some sheet metal work and I'd be in business.


Your photo shop job makes the stove look better too... ;)

T

Look at the weight of CO VS O2
When do you want the detector to go off when it collects to two feet above the floor or hours after your death?
BTW fins up is a close second to fins vertical. Horizontal fins make me laugh since they are about useless.

TOM!!...Great idea with the heat sinks on the coal stove......I had about the same idea around 1974-5 ...I had a little plant that manufactured the "Pentagon Wood Stove"...( any one ever hear of it?)  This was started during the Arab Oil Embargo of the 70's...I applied for some grant money that was available to alternate energy type manufacturers and lost out to a solar powered $hitter....My Idea was to use a masonary heat sink to store and re radiate heat from a wood burning stove.....We sold several thousand of the "Pentagon wood stoves" ( They are 12 sided, shaped like a pentagonal dodecahedron) but never got to persue the masonary heat sink idea......

I'll mount the CO detector lower then, Tnx.

I agree about the horizontal fins being NG, but the bottom base of those two sinks are filled with bumps, so will not seat flat. I need a milling machine.

Yo Steve - Cool on the Pentagon stove. The mid 70's sure was the time to produce them.

 I also thought that putting some large, flat slate slabs on the top and sides of the stove wud do the same thing. Just like those expensive Hearthstone stoves or even large stone fireplaces.    Yes, the coal stove heatsink idea continues to work well and probably the best working device in the whole house right now... :-)


Later -

T

Voo-doo...

I vote with Patrick's idea... that will move a ton of air across those fins...
The chimney effect will blast air I'd bet.

The other thing is - or the next step up - is a water jacket.

Oh, wait a minute... isn't that exactly what the old tyme home coal fired boilers were??

               _-_-bear

Re the CO detector...theoretically CO is heavier, but it tends to rise, mixed with the rising air near the stove. If you mount one detector low and the other higher on the wall, the higher one will always read higher; we've tested this in several locations. You shouldn't mount it within about a foot of the ceiling though, since the airflow is reduced in the corner and the detector tends to get bypassed. Too near the stove probably isn't good either, the smoke, if any, and the heat is hard on the detector.

I've got a combo smoke/CO model on all 4 floors, with the detectors wired together so if one goes off, they all go off.

A water jacker might not be a bad idea in climates where humidifiers are necessary in the winter. Even here we sometimes run a humifier when the natural gas furnace is in high gear. To be sure having very dry warm air gives me a headache for some reason. It is not CO fortunately, That was the first thing suggested as a headache source.

Yea, me too on the head ache. I was visiting friends from first grade Saturday and the fireplace was cranking. Dried me out for a day.