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Author Topic: Higher efficiency conventional build scotch type  (Read 3706 times)

slimjim

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Re: Higher efficiency conventional build scotch type
« Reply #15 on: March 24, 2015, 01:09:48 PM »

PM sent with my phone # let's talk!
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ben

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Re: Higher efficiency conventional build scotch type
« Reply #16 on: April 20, 2015, 06:44:46 AM »

I've updated the gallery for probably the last time until I get a pad poured to install. That won't probably be till july or so... We will see how busy the summer is. I haven't finished the outside ash cleanout door. I have to line it with matching steel. It's just white now. I also have to do the wiring in the outside box for the aquastat. The picture of the damper actuator was just for testing. I wound up going a little overkill on the insulation if there is such a thing. The sides, bottom and top are R44 and the front and back is r28. Should be good enough. I have to add weather stripping to the outside door also.

Here is the gallery
http://s1300.photobucket.com/user/benamyeby/library/boiler?sort=3&page=1

One attached here:


In Liberty
Ben


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ben

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Re: Higher efficiency conventional build scotch type
« Reply #17 on: July 31, 2015, 07:02:31 AM »

Another update! So she is home and installed. I haven't sparked it up yet, its been very hot outside. So another update is to follow.

So it is hooked up to heat the garage and the house. The boiler is 30 feet from the garage and then about another 20 from there to the house basement. The logstor is installed in a 6" drain tile and comes up through the wall of the garage above the sill plate. The garage is a floating slab and the outer perimeter is 20" of concrete. So I wasn't going to drill two holes in it. The logstor goes as the crow flies to the corner of the garage (closest to the house) then over to the house. My pump is in the garage, there is a zone valve and small air/water hx there to keep the snow off the car. In the basement there is only a water/air hx in the plenum and a 30 plate hx for the domestic hot water. I really tried to keep the pipe length and fittings to a minimum. I ended up using about 88 feet of logstor.

I added my extra length of chimney when I got it home and the rain cap/spark arrestor (required by insurance). The insurance guy actually really liked it and doesn't require any extra fee's for homemade. I have include a finished pic with the firebrick and baffle plates. I was fairly close with my calculation of water capacity. I got a flow meter for the hose and put 210 gal of water in. I can get another 10 or so but I'm not sure how much expansion room I need until I get up to temp for the first time. I put rust inhibitor in ( I got from an industrial boiler supply place) and sent them a water sample. I wonder how accurate water capacity claims are on the factory made boilers. I wanted and accurate measurement for calculating efficiency when its going.

I am happy with this taco bumblebee pump except its flow display is not accurate at all. It seems to measure the rpm of the pump to calculate flow. But even if you partially close the isolation valve the flow display barely changes. The impellor still obviously turns and there is little to no flow. Just a note to someone considering this pump.

I had to move a couple apple trees to put the boiler here. The little one is looking good. The big one barely has any leaves except maybe 2 branches. We will see how they fare. Also it sure is hard to get grass to grow with free range chickens. Every day I get home they are gobbling up seed...

gallery link  http://s1300.photobucket.com/user/benamyeby/library/boiler?sort=3&page=1









In Liberty!
Ben
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mlappin

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Re: Higher efficiency conventional build scotch type
« Reply #18 on: August 01, 2015, 07:58:26 AM »

Quit feeding the yellow cat and the free range chickens won’t be a problem for long.
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ben

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Re: Higher efficiency conventional build scotch type
« Reply #19 on: August 06, 2015, 11:31:42 AM »

Another update. Sorry about the frequent updates, Its a little dead on the forum in the summer but I have to post what happened or I will forget the numbers.

The temperature outside went down to 21 C or so last weekend so I had her maiden burn. Just a small fire to get it up to temp and make sure everything is fine.

I loaded 1/2-3/4 of a wheelbarrow of sawmill scraps and about 6 5" pcs about 2' long of poplar and a few pieces of ash. I didn't weigh it, also I'm waiting for my new moister tester. The fire lit easily with the under-fire air. The 210 gal of water went from 77 deg to 190 deg in 1 3/4 hours. The firebox was certainly not full.

1751 Lbs x 113 deg = 197,908 btu

197,908/ 1.75 = 113,090 btu/hr

It drew a surprising draft for naturally aspirated. The probe in the chimney registered on average between 105-115 deg F above water temp ex- water at 160 chimney at 270, water at 175 chimney at 290.
The highest the flue temp recorded was 305.
There was a fair amount of condensation dripping from the ash door on start-up and until the temp reached about 120. The boiler cycled on and off a few times that evening until the wood was gone. There was a very thin black film on the side walls of the firebox and heat exchanger tubes. This seems to have dried up when the temp hit about 175.

The initial run went better than expected but about what I hoped. I have a PWM dc motor speed control on the way so then I can add my blower fan and I also ordered a thermocouple for the firebox. This should let me know the water temp, flue temp and firebox temp.  I wired an empty beer can right up to the gasification tube to see if it would make it over 1200 deg there. It didn't melt and drip off but the corners did seem melted. It was drooped down about 1 1/2 times as long as when it went in. So that makes me happy that we are seeing fairly high temps up there in the firebox.

I left my pump run until the water was cold, We used "free" hot water for about 3 days after the fire died!

When it gets colder in the fall I will do a complete test... and report!

In Liberty
Ben
« Last Edit: August 06, 2015, 11:56:50 AM by ben »
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fryedaddy

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Re: Higher efficiency conventional build scotch type
« Reply #20 on: August 28, 2015, 08:32:24 AM »

I wouldn't worry too much about the cresote issue, it can be cleaned easily.

I have (6) 4" tubes around 48" long in my stove. My manufacturer sales a
wire brush that fits a long handle to run through the tubes.

I've ran the stove for a month and didn't have issues.

I batch burn but don't think you'll have issues cleaning it once a week.
takes me 15min at the most to clean.
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Dragfluid

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Re: Higher efficiency conventional build scotch type
« Reply #21 on: October 27, 2015, 05:43:42 AM »

Just looked at your gallery.  Nice craftsmanship!
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ben

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Re: Higher efficiency conventional build scotch type
« Reply #22 on: November 10, 2015, 12:17:30 PM »

Thanks for the comments!
Well I couldn't handle it anymore, I was to excited to turn off my water heater. I fired the boiler up Saturday morning. Its been running 4 days. It hasn't been all that cold, just below freezing at night but up to 5-10 C during the day. The boiler has been doing a lot of idling. I'm running at 185 5deg differential. It will overshoot and stop at about 188-189. The longest idle time would be around 8-9 hrs (estimate). So I'm hardly burning any wood. It smokes a little when it starts after a long idle until the firebox warms up (maybe 2 minutes to a roaring fire).

I didn't weigh any wood yet but I did put my thermocouple temporarily in the firebox up by the secondary air tube. When the burn cycle starts the temp at the top of the firebox climbs, the smoke stays until it hits about 8-900 degrees F. After that the temperature by the firebox baffles quickly climbs and hovers around 1250 degrees. It started raining after this pic was taken so I took the camera in but the highest peak temp I recorded was 1375 F. I'm quite pleased with that. That should be doing a fair bit of secondary combustion.



A quick link some may find informative:
http://www.uky.edu/bae/sites/www.uky.edu.bae/files/AEES-36_0.PDF

electrical box with PWM speed control added


new forced air, air intake with filter. I was worried about snow drifting in.




On a side note, I got a new to me toy and I've been using it for pretty much everything.
Removing front door system to install a new tighter one.


I do intend on weighing some wood and calculating efficiency. And will keep everyone posted when it actually gets cold and I convert some wood to btu's!

edit: I forgot, It took the water from 53 degrees up to 189 in an hour and a half. So 1751lbs x 136 deg = 238,136 btu (not counting steel)   / 1.5hr = 158,757 btu/hr

It doesn't seem to burn as efficient when warming up initially until the water reaches about 165 degrees. I will time a cycle when I up my differential.

In Liberty
Ben
« Last Edit: November 10, 2015, 12:24:01 PM by ben »
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ben

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Re: Higher efficiency conventional build scotch type
« Reply #23 on: December 09, 2015, 09:50:03 AM »

Well, I'm a tinkerer and can't quite leave anything alone.

I've been playing with the air speed control to tune the firebox temp and secondary combustion quality.  I was getting temps in the 1300-1450 range but it seemed somewhat sporadic , It depended on how much wood was loaded and how many cycles after the wood was loaded. It seemed to smoke more and have lower temps when fresh wood went in.

It was my suspicion I didn’t have enough secondary combustion air.  So first I added an adjustable plate in the blower stream to block off some of the underfire air and therefore push more to the gasification tube. Things were better. I reduced the fan speed which made the fire less roaring but more of the smoke was burned off. The primary fire would have been creating less volatile gases.  Still about the same temps but a little less smoke out the stack.

Then I added a second gasification tube underneath the first. I made it out of some 2x3” tube I had laying around. I figured I had to much friction loss on the gasification tube to get that quantity of air above the fire. This helped too but was still sporadic.

I thought I still needed more air… So My under fire air comes in from the back and over the ash pan and up slots that are about 1.75x5” in the bottom V of the firebox. There was 3 of them, The one at the very front was kind of hard to poke ash through because its fairly low right inside the door. So overtop of this air hole I bolted in a piece of 3x5 tube with a ramp to cover up the whole air slot. (if that makes sense, I will take pics soon). On top of the tube I welded a plate that ramps toward the firebox baffle plates and has 2 big slots in it to blow air directly towards the original gasification tube. The big tube is about 16” long and stops flush with the bottom door flange. I then took out the divider plate and turned the fan back to high.

This made a drastic difference. When I stoked the fire this time my thermocouple probe jumped to 1400, then 1650 then 1875 and then went blank… It has melted/broke my probe. When I cracked the door the flames shooting off of the air intake tube in the front of the firebox looked like a torch. The flames started about 4” away from where the air was injected and was swirling around the curves on the baffle plate. I have been through both of my probes and have a new stainless steel higher temperature one on the way.

All of these changes have been made with the boiler still making usable heat so I’ve been letting it burn out and do the change and start a new fire all before the water temp goes below about 150.  My next step is to sawzall/grind off the new rectangle gasification tube all the way back to where it makes its 90 bend in the top of the firebox. This will get more flow back there.

So by now I have figured out a few things  I would change if I did it all again. First I had to put on a rain cap with a small mesh spark arrestor. That thing gummed up fast and dripped creosote all over the roof. It seemed to gum up when I was tinkering and burning much less smoke and just after the fan kicked on but before burning the smoke.  I would also move my water level indicator. It is a high temp silicon tube in a nice, easy to see spot but got dirty from smoke out the door pretty quick, you need to wipe it off to see the water level.  And If starting over I would make the original gasification tube much larger for flow or have  a second fan that could be controlled independently for maximum efficiency.  The original one was certainly better than nothing but it was improved greatly after modification. The baffle plates seem to work good, I would maybe extend them a little bit lower on the outside edges. But that would take away some firebox space.

I’m going to try and get a video of the secondary combustion. It sure is hard though with no viewing window!

I hope this might be helpful to someone planning a build or wanting to modify theirs!

In Liberty
Ben
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mlappin

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Re: Higher efficiency conventional build scotch type
« Reply #24 on: December 09, 2015, 03:57:35 PM »

Maybe something like this for a view window? This piece of glass cracked, thought maybe not enough air for the air wash but actually the silicone would creep in and glue the glass in solid, couldn’t expand and contract freely and thats what cracked it.





« Last Edit: December 09, 2015, 10:08:15 PM by mlappin »
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mlappin

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Re: Higher efficiency conventional build scotch type
« Reply #25 on: December 09, 2015, 03:58:31 PM »

Have a video as well but photo bucket is being stupid
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mlappin

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Re: Higher efficiency conventional build scotch type
« Reply #26 on: December 09, 2015, 04:28:16 PM »

I outstupided Photobucket…..

Still with the cracked glass but here’s what a fire looks like in a G400 secondary chamber.


http://vid160.photobucket.com/albums/t167/Marty_Lappin/HeatmasterSS/IMG_1454_zpsd7arist9.mp4
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ben

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Re: Higher efficiency conventional build scotch type
« Reply #27 on: December 10, 2015, 06:36:21 AM »

Hey, that little window looks good! Did you use the special temperature glass? I would have to take my door off and bore a hole through it and then add a tube of some sort through the insulation, similar to yours it looks like.  The down draft gasser sure does blow some fire down there! It's nice to watch it with the door closed so you know your not affecting the burn when you open the door!

Maybe a window is a job for the spring shutdown for me.

Thanks for posting that!

In Liberty
Ben
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mlappin

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Re: Higher efficiency conventional build scotch type
« Reply #28 on: December 10, 2015, 01:44:55 PM »

Both pieces in the flange are some kind of stainless, the 1/4” piece is something Dad brought home from work when he was a tin knocker yet for union shop. They were gonna toss it all out and he brought home a 5 gallon bucket of drops. Have used it for base plates for the grain dryer legs, or any other supports that are direct contact with cement. The thin stuff was leftover from last winters project of making a new reservoir to dump waste oil in.

Clamped em together and cut the square out with a plasma cutter then faced em in the bridgeport, after that used a 2 1/2” carbide hole saw in the bridgeport for the center hole. Used a piece of 2 1/2” 409 tubing I had left over from last fall/winters project of building a new waste oil boiler. I then cut a slot in the bottom and each side for an air wash effect, all slots are angled thirty degrees in the same direction to get a swirl effect. The slot on the “right” side as you are looking at it actually runs up, then makes a 30 degree angle down to prevent water from just running into the tube if its raining.

Took the secondary door off the boiler and placed it on two plow beams each covered with a towel to prevent scratches then built two “L” brackets to bolt to the bridgeport table to act as stops so if the holesaw bound up the door couldn’t try to spin. Could do the outer skin of the door and the middle layer but had to flip over to get thru the inner skin. Slid the tube in, got the flange slid a 1/8” on the tube then bolted the flange down, took some 26 gauge sheet metal and laid it around the flange to protect the paint on the door from any weld splatter.

Used #10 nuts with the centers drilled out for spacers to prevent clamping the glass down tight.

Used a scotchbrite pad on a right angle die grinder to pattern the outer piece of stainless.

If I was to do it again I’d use 2” tube instead, the air slots I’d leave the same but with a smaller tube the air wash should work much better. It kind of has a dead spot for 2-3 inches in from the fire where ash settles. When I have it open I just use a piece of bark to scrape the ash out.
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hondaracer2oo4

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Re: Higher efficiency conventional build scotch type
« Reply #29 on: December 10, 2015, 02:52:16 PM »

Ill be interested to see how your air wash works out for you, it will be a pain to try and clean that glass if it fogs often. Richard Modified my door so that people at the shows could see the secondary. I believe he bored a 2 inch hole all the way through, then he welded very small L brackets on the sides and on the bottom of the hole which excepts a piece of glass which slides right down into the L brackets. The glass fits snug enough so that it makes a seal actually. It does get fogged over though and I slide it out every other day or so and clean it off. I have to use some water and some ash to clean it since it is caked onto the glass. Richard wants the door back though for next year. I think I may mod the stock door after it gets swapped out, it really is handy to be able to see what is going on in the secondary other than just looking at the flue pipe.
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