# Anyone else doing a DIY oil to pellet burner conversion?



## treetopflyer (Jan 22, 2012)

Wondering if anyone else is doing this and might like to share ideas, results, etc.

I have a Biasi 4 section cast iron boiler that was fired on #2 fuel oil. I wanted to convert it to burn wood pellets, but after looking into what's available, I think the imported pellet burner guns are just too pricey and they don't address the issue of ash removal. Ash removal is really more about the boiler than it is about the burner. In the case of my Biasi boiler, it'll hold about a weeks worth of ashes. 

I burn more fuel (oil or pellets) than most people because my house needs some work. Yeah... I know... but I'm working on that...  I chose to get away from buying oil so that I could invest the money into tightening up the house and replacing some ductwork on my air handler for the large room over the garage.

Last year I burned waste motor oil in a custom burner that I built. I started with a Beckett AFG burner and added a custom drawer assembly with a 400W preheater and a digital temperature controller connected to a solid state relay to controll the preheater behind the nozzle.  It worked great, but it's such a hassle collecting waste oil and I found that towards the end of the winter I couldn't get enough to heat the house with, so I decided to move that into my shop and build a pellet burner for my boiler.

The Biasi has a cast iron cover on the firebox that the burner bolts up to. I removed that cover and fitted a 1/4" steel plate to replace it. I built the burn pot from a short piece of 4" angle iron welded to the plate and lined it with firebrick. firebrick cuts easily enough with a masonry blade on a table saw. I slotted it on the bottom where it meets in the center of the angle iron so that I can blow some primary combustion air under the firebrick and use the angle iron as a duct to get the air under the fire.

The feeder tube is a piece of 1 1/2" black iron pipe. It's cut off flush with the 1/4" plate and positioned at a 45 degree angle so that it allows the pellets to drop into the burn pot. My phase 2 burner will use 2" pipe insteas of 1 1/2" pipe because I've found that a couple of times that the pellets have jammed in the feeder tube and it was only necessary to give the tube a tap with a wrench to get them moving again. So I learned that 1 1/2" pipe will work most of the time, so I think that 2" pipe should work all of the time.

I put two 3/4" holes in the plate for primary combustion air. One hole is between the fire brick and the angle iron, the other is right on top of the firebrick so the pellets cover it as they drop into the burn pot. I built a primary combustion air plenum, a small steel box on the outside of the plate with a damper in it so that I can adjust the airflow between the two holes. I'm using a small centrifugal blower from a dishwasher as the primary combustion air blower. Even this little blower is overkill and I have the blower inlet restricted to leave an opening about the size of a quarter. 

My chimney is about 10' of 6" type L wood stove pipe that goes through the ceiling and roof of the boiler room. It's not much of a chimney and I didn't trust it to make enough draft to safely operate a pellet burner. I had an old power vent blower in my shed, so I brought it in, cleaned and lubed it, and installed it on the back of the boiler to force the gases up the chimney. I'm sure this is why I need so little combustion air from the primary combustion air blower. Someone else with a better chimney may not even need a power vent, but it's absolutely imperative that gases never, ever be allowed to go back up the feeder tube. Pelix uses .03" as a minimum draft requirement for a chimney and I think that's probably a good universal standard. For pellets, I'd measure that over the fire rather than at the breach to account for restriction in the boiler itself.

Ignition was an interesting part that required a little tinkering to get it to work right. I wanted hot air ignition, not hot surface ignition. I didn't want anything laying in the burn pot getting eaten up by the fire over time. I welded a piece of 1/2" black iron pipe in and through the primary combustion air plenum, stopping just short of the upper inlet port through the 1/4" plate so that hot air blown through the pipe would blow directly onto the pellets.

I looked at the Leister wood chip and pellet ignitors and they looked perfect for this, but they're just too pricey at $275.00. I went to the local discount warehouse and bought a cheap chinese heat gun and took it home and dissassembled it. It looked perfect for the job. It had a centrifugal inline blower and a ceramic heating element. It's weakness is the little 17V DC motor that spins the blower. I went through 2 of these in 3 weeks. The brush holders are made of something not much stronger than an aluminum beer can and both of these tore up the brushes after about a week and a half of service. I had another heat gun around. This one has a squirrel cage type blower and nichrome heating elements. That one works much better and it's still working just fine after a month, but it looks a little strange hanging off the front of the boiler. It's the one that Harbor Freight sells and it's sold in a lot of different stores as well.

The hopper and the auger were my next build. I decided to use a 55 gallon barrel as a hopper. It'll hold about 7 bags of pellets, and about 6 and a half bags are usable fuel. I could have gotten fancy and tapered the bottom, but it was easier to dump an extra half a bag of pellets into the hopper than it was to spend a day with a cutoff wheel and a mig welder. Small augers aren't easy to come by either. I put the barrel up on a stand and I needed about 42" of auger. I chose to keep the auger as short as possible to make the motor lead an easier life. I bought a commercially made auger motor, 2 RPM, CCW rotation, off ebay for $65.00. The auger tube is a piece of 2" ID black iron pipe. I bought 5 Rotodigger RD-2 bits. These are for digging in gardens, putting pipe or wires under sidewalks, etc. they chuck into a drill for normal use. I cut 4 of them off in the bandsaw and laid them all out on a piece of angle iron to keep them true. I welded the shafts with 7018 rod and my stick welder and mig welded the flighting together. I connected the auger to the motor with a home made drive coupling made from a piece of 7/8 rod.


end part 1


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## salecker (Jan 22, 2012)

Hi Treetopflyer
 Great thread,needs pic's.says the guy who can't post pic's.
 Sounds like you love to tinker and build things.
 I have never used pellets for heat,but heat my garage with waste oil,i have no trouble getting oil,i have about three winters worth now.Used cooking oil works great too,unless you can use it in your truck.
 On a different forum,different content and all,there is a lady that burns nut shells in her pellet stoves.They are a by product from a processing plant.She buys them by the dumptruck load,she has her own dump truck.Costs her peanut's to heat her house for the winter:}
 Thomas


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## treetopflyer (Jan 22, 2012)

Begin part 2

When I tested the hopper / auger assembly, I ran it for 15 minutes and weighed the pellets that came out. Multiply that times 4 and I had an hourly feed rate of 12.38 lb per hour. Roughly equal to a .75gph nozzle on an oil burner at 100 psi.

Now the challenge was to control it and to build in some failsafes. I settled on using a Basic Stamp 2 microprocessor from Parallax. I used thier development board, then thier prototype board to make the actual controller that's in my boiler now. I used a cad cell from an oil burner to allow the controller to see if fire was present, or should I say not present. The first test run showed me that glowing embers in the burn pot will fool the cad cell into thinking there's fire when there's not. The solution was simple, test for the absence of fire, not for the presence of fire. If the fire is out or fails to light, the pellets will come in and cover up the burning embers. If they light, that's great, if not they will cover the light from the embers and the controller will retry once and then lock out on safety if there's still no fire. I also designated an input for a thermal disk to be installed on the feeder tube. This will sent it into immediate lockout if the feeder tube temp reaches setpoint. I haven't installed the disk yet, but I've measured the feeder tube temp at various times. It's hottest when everything is off after a burner cycle is complete. I think a 250 degree F disk will do the trick nicely.

In phase 2, I'm going to reverse the function of the switch so that the switch will open on temperature rise rather than close. This will protect the wiring for the switch as well. A wiring fault will send the controller into lockout as opposed to causing the safety limit not to work at all. That makes better sense than the way I have it now.

It took about 10 rewrites of the software to get it working perfectly. Tweaking the ignitor cycle was the biggest one. You don't want to run the ignitor for too long because it moves a lot of air and it will empty the burn pot rather quickly by burning up all the pellets too quickly. Too short of an ignition cycle will cause it not to light at all (sometimes) and go into safety lockout. So the solution was to stretch the ignitor cycle out longer than it needs to be and pulse the auger in 2.5 second intervals to keep something being added to the burn pot during the ignitor cycle so the ignitor can't completely empty out the burn pot.

So the thing is heating my house and it's cut my fuel cost in about half as compared to heating with fuel oil. I'm burning the cheap premium hardwood pellets from Maine Wood Products that Walmart sells for $3.88 a bag in Biddeford, ME. I have to empty the ashes weekly during the heating season because of the tiny firebox in the Biasi boiler, but it only takes 15 minutes so it's not a big deal. I know there are cleaner burning pellets out there, but I want to keep my design so it'll deal with the cheap pellets well because I like the price. $3.88 per bag wether I buy 1 bag or a ton is hard to beat.

I cleaned the boiler after about 5 weeks use. It was unnecessary to do a full cleaning, but I wanted to see what's in there. I did not clean the boiler when I installed this. Turns out it burns itself clean. Only a tiny bit of fly ash was in the upper heat exchanger, it looked like a new boiler inside. It even burned off the crap left behind from burning waste oil. I've set out from the beginning to try to let the gases burn through the boiler rather than completing the whole cycle of combustion right in the firebox. I use as little primary combustion air as is possible and let the secondary combustion air that comes down the feeder tube mix with the gases and burn on it's way through the heat exchanger. I nearly lost my moustache and eyebrows a few times while I was experimenting with the airflow adjustments. Wood gas is a very powerful thing and we don't ever want it to load up and ignite suddenly. Turning on the power vent during the ignition cycle prevents that and since I wrote that into the software, it hasn't happened again.

So phase 2 is coming up really soon. I'm going to start with another 1/4" steel plate. I'm going to reduce the size of the burn pot by using 304 or 316 stainless and eliminating the firebrick. I'll see how stainless holds up without firebrick. The space under the burn pot where the ash collects is big enough that I could put another small auger in there to auger the ashes out into an airtight steel box so that I can put an ash pan in there and dump it from there as opposed to removing the burner weekly. 

In my case with the small firebox on the Biasi boiler, I think the gun type solution is not the best way to go because it's too much work to clean it. This is why I went this route instead of building a gun type burner. If I can get phase 2 completed succesfully, the thing will auger out the ashes into a pan by itself so All I need to do is empty the pan and check the heat exchanger a couple times a year for fly ash buildup. I've got less than $500.00 into this so far and it's been heating my home for about 6 weeks now with no major issues so I think I'm onto something here with this burner design, but it's not quite ready for prime time yet...

After I see how well the stainless steel holds up in my phase 2 burner, I'm considering building a gun type burner for my son. He has a 5 section Vaillant boiler with a huge firebox and a swinging door that the burner is mounted on. This looks like a perfect scenario for a gun type burner. I'm thinking that if the stainless steel holds up in mine, some 4" heavy wall stainless steel pipe might make a nice blast tube on a Beckett AFG chassis to lead into the firebox and attach a slightly larger piece of stainless for the burn pot.

Has anyone else built thier own burners? I'd be very interested to hear about different burner designs and how they work. Clinker formation, maintenence, etc.  Sharing info, pictures, etc. might be beneficial to all of us and it might help the commercial guys wake up and see that these things can be built in the US and they don't need to be imported from Europe to work properly. Maybe someone with enough money to certify the thing will see it and build them so we can all afford to buy one.

Next week when I clean it, I'll try to clean up my boiler room a bit and get some pictures to post here if there's any interest


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## treetopflyer (Jan 22, 2012)

Hi Thomas,

I will post some pics next week when I have it apart to empty the ashes. I realize that it's probably pretty hard to visualize the stuff in this burner without pictures. I also need to clean up my boiler room a bit before I shoot pictures so people don't dismiss me as a lunatic too quickly (that should take a little time). You know how when you get done with a project it looks a bit like a bomb went off... Spilled pellets on the floor, tools on top of the boiler, etc...

Mark


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## DexterDay (Jan 22, 2012)

treetopflyer said:
			
		

> Hi Thomas,
> 
> I will post some pics next week when I have it apart to empty the ashes. I realize that it's probably pretty hard to visualize the stuff in this burner without pictures. I also need to clean up my boiler room a bit before I shoot pictures so people don't dismiss me as a lunatic too quickly (that should take a little time). You know how when you get done with a project it looks a bit like a bomb went off... Spilled pellets on the floor, tools on top of the boiler, etc...
> 
> Mark



Wow........ Very nice write up. Looking forward to pics. This is my formal welcome and my subscription to this thread. Cant wait for Pics.....


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## thecontrolguy (Jan 23, 2012)

Sounds pretty cool, except I'm more interested in the details of the waste oil burner.  Anyway, in the interest of safety, you might consider what happens if you get a spark or flash fire up the auger and into the pellet bin.  This happens in LOTS of residential pellet burners.  The big pellet boiler at my workplace has an auger feeding from an outside hopper, into a metering bin that has a slide-gate.  The gate opens when pellets are needed and closes when they are not.  There is also a simple deluge tank of water attached to a water valve that looses the water if the sensor, strapped to the last feed auger, senses temperatures that indicate the fire has expanded into the auger.  Fairly simple, all safety devices and commercially available or fabricated.  Good luck.  Please PM me if you are interested in sharing info about the oil burner.  I am thinking on this as backup for next year.


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## treetopflyer (Jan 24, 2012)

The slide gate is a neat idea, but won't work for me since I spin up the auger continuously whenever the thing is running. It would be open whenever the burner is running, but the deluge system sounds like a simple and effective safeguard. I'd hate for that to go off by mistake though. The pellets would expand into wet sawdust and fill the auger and feeder tube with snot. Still better than a hopper fire though. What are you using for a temp sensor? A bimetal disc? 

I sent you a PM about the waste oil burner. I'll get you some pics.


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## thecontrolguy (Jan 24, 2012)

treetopflyer said:
			
		

> The slide gate is a neat idea, but won't work for me since I spin up the auger continuously whenever the thing is running. It would be open whenever the burner is running, but the deluge system sounds like a simple and effective safeguard. I'd hate for that to go off by mistake though. The pellets would expand into wet sawdust and fill the auger and feeder tube with snot. Still better than a hopper fire though. What are you using for a temp sensor? A bimetal disc? I sent you a PM about the waste oil burner. I'll get you some pics.



A bimetal disc might work, however a high-limit controller with remote bulb like a Honeywell L4008 might also work. The devil is deciding if you use a normally open, powered close bulb that will open in a fire OR the power failed(!) Or you use a normally closed, powered open valve and hope it works when the time comes. I don't recall the models of the deluge valves we have at work, and I am not back until Wednesday for day shift. However, to implement one of them, you just weld a pocket that the bulb fits into on the side of the auger tube.  It will sense the heat of the tube.  In a fire the pressure in the bulb pushes open the water valve and the water flows.  No need for electricity, works all the time.  For sure, isolate it with hand valves for maintenance.  Yes, it makes a mess, but better than several hundred pounds of pellets in the fuel hopper going up and filling the building with nasty acrid smoke. (or burning it down)!

Got the PM. Thanks!  I will follow it up.


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## treetopflyer (Jan 29, 2012)

Here are the pics as promised. I let it run a little over a week without emptying the ashes since the weather has been fairly mild here this past week. I cleaned it yesterday and took the pictures.

Keep in mind that this burner is just the phase 1 test. Phase 2 will include such luxuries as air shutters on the combustion air blower and on the top of the feeder head at the end of the auger tube and a few other things that will completely eliminate the use (or abuse) of aluminum tape.

Here's the boiler as I run it now. I took this one just before cleaning it.


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## treetopflyer (Jan 29, 2012)

Here's the hopper / auger assembly.


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## treetopflyer (Jan 29, 2012)

Front of the burner showing the feeder tube at the top, the heat gun that I'm using for an ignitor, the combustion air plenum, and the two yellow wires are for a cad cell to let the controller see if there's fire in the firebox.

It's hard to see from here, but the heat gun blows into a 1/2" black iron pipe that goes through the combustion air plenum and stops just short of the opening for the upper combustion air inlet so that the heat blows directly onto the pellets, but when the ignitor is off, the combustion air blower can blow through the same hole into the burn pot. I cycle the ignitor for 15 seconds at the start of every burn cycle before I preload the burn pot. The heat gun blows a good strong stream of air. This keeps the ash and small clinker pushed back so I'm not constantly scraping out the burn pot..

The second pic is the inside of the combustion air plenum looking in with the combustion air blower removed. You can see the damper that allows me to divide the airflow between the upper and lower (under the fire) inlet ports.


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## treetopflyer (Jan 29, 2012)

Here's the burn pot and the firebox with a weeks worth of crap in it. Keep in mind that a weeks worth of buildup at my house is probably two to three weeks at a "normal" house. I do have to tighten this place up... 

Looks like the burn pot is largely wasted space and I could build it about half as long as it is. You can see where the ignitor is doing a good job of keeping the pile of crap pushed back by using it to blow out the burn pot it at the beginning of every burn cycle. Unfortunately, I forgot to take pics of the burn pot after cleaning it. It's just a piece of angle iron welded to the front plate with some shims welded inside the angle iron to support the firebrick so that I can blow air between the firebrick and the angle iron through the lower port in the combustion air plenum. Doesn't really look like the bottom port is doing anything because it's filled with ash and clinker. I think I can safely eliminate it from the design in phase 2.

Looking at this, I see some room for improvement in phase 2. By going to a smaller burn pot made of stainless and putting an ash auger under the burn pot, I cab all but eliminate this buildup. Even still, this may look like an awful mess, but it takes 15 minutes once a week or so to scoop out the firebox and burn pot and run a soot vac through it. Here's a weeks worth of crap in a small metal bucket. This is all that was in there except for the little bit that the scoop wouldn't get and I cleaned with the soot vac. The bucket is 9" tall and 10" arount at the top. It's a very tiny firebox on the Biasi boiler.


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## treetopflyer (Jan 29, 2012)

Here's the heat exchanger. There's more than a weeks worth of buildup in here. I normally limit my weekly maintenence to scooping out the firebox. The photo doesn't do it any justice. The pile of fly ash is what settled against the cover plate and does not go all the was back through the heat exchanger. The pic on the left shows the heat exchanger after I took the soot vac and removed only what settled against the cover plate. I haven't cleaned it at this point, just cleared away this little pile of ash about an inch deep so you can see what's really inside the heat exchanger.


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## treetopflyer (Jan 29, 2012)

These pics show the heat exchanger after blowing it out with an air hose. No brush needed. I just turn on the power vent and it carries most of the fly ash up the flue as I blow it out instead of filling the boiler room with dust. I have to start slowly at first, but the further back in the heat exchanger I blow, the more air I can put to it without letting very much dust out into the boiler room.


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## treetopflyer (Jan 29, 2012)

The controls for the pellet burner. It's a parallax prototype board complete with a wall wart transformer to power it. In one pic, you can see the 4 transistors and thier base resistors that I use to switch the solid state relays. Phase 2 will use a darlington array instead of the individual transistors and the controller will be seperate from the relay box. 

The mechanical relays have 120V coils and I use two of them to sense zone call and burner call for the controller board from the zone control panel. The third is not connected and it's just to keep a spare relay handy in case one fails.

Burning pellets is a lot different than burning oil, even waste oil. You can't just switch off a pellet fire, you have to let it burn out by stopping the auger and keeping combustion air going. In this case, I also have to keep the power vent going too to make sure there's good draft while all this is happening. 

If there's no zone call when you do this, you'll make steam in a boiler this tiny, so if we're ending a burn cycle with no zone call we're going to have to do something with the heat from that fire. If there's already a zone call, then the post burn heat will take care of itself, but if there isn't a zone call, in other words, if the last thermostat is satisfied, we have to divert that heat somewhere so we don't overheat the boiler, so I used my superstore tank as a dump zone for the duration of the 4 minute post burn cycle under these conditions. The controller senses no burner call and no zone call and powers up the circulator for the superstore with one of the solid state relays. I have a tempering valve on the superstore tank anyway, so handling the extra heat in the tank isn't a problem, no one gets scalded and the tank is no where near relief temperature, ever.

The controller has a couple of failsafes built in. I have provisions for a thermal disk to be mounted on the feeder tube (no I haven't installed it yet and I probably won't until the phase 2 burner is in place). I wrote a subroutine that sends the controller into an immediate lockout if the temp sensor on the feeder tube is tripped and flashes the red LED. a 250F thermal disk should do the trick.

If the controller sees no fire at all, it will retry once. If it still sees no fire, it will lock out and flash the yellow and red LEDs alternately like the lights on a school bus.

The switch to the left of the outlets where the auger and ignitor plug in is labeled "pellets" in one position and "oil" in the other. That simply switches control of the power vent between the boiler's original control to the pellet burner control. This way, I can simply plug in my oil burner gun, flip the switch, and use it for a backup. There's a pigtail that hangs under the same switch box that the combustion air blower plugs into that isn't shown in this picture that's also controlled by the switch. I can plug my waste oil gun into that, or I can plug my #2 oil burner gun (the riello) into the twist lock plug shown in the picture. Between the oil guns and the Hunter wood furnace that's also in the boiler room, I have plenty of backup alternatives.


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## treetopflyer (Jan 29, 2012)

So I've learned quite a bit from the phase 1 tests. The thing has been absolutely reliable, no complaints there, but I see a better way to do a number of things. The burn pot design and the addition of the ash auger will be the first thing to get updated. I think the stainless burn pot will be a better way to go. Less ash and clinker will stick to it and an ash auger that fits under the burn pot to carry most of the ash out into an enclosed collection container will be really convienient with such a tiny firebox.

I've got a lot of things that I'd like to do differently, like building an auger that will drop into the top of a 55 gallon barrel and clamp to the side of the barrel. This will allow me to set the barrel on the floor and make it easier to add pellets. The way it is now, my wife is too short to add pellets to the hopper and I don't want her standing on a milk crate lifting bags of pellets...

Speaking of bags of pellets, the pic below is what I'm burning. These are the absolute chepest pellets that one can buy in southern Maine. Maine Wood Products pellets for $3.88 a bag. Doesn't matter if you buy a ton or a single bag, same price. Walmart in Biddeford, Maine has them. I go right by there every day on my way home from work so it's really convienient for me. I'm not convinced that the higher quality pellets will be a better bottom line. I'd rather make provisions to handle the ash and clinker from these cheap pellets and beat the bottom dollar out of the heating cost, so for me, its all about the numbers.

So assuming that the btu value of my cheap pellets for $194.00 / ton is 8000 btu per lb, and assuming that the $250.00 / ton high end pellets carry 9000 btu per lb, that's 2,000,000 btu difference per ton and a cost difference of $56.00 per ton. Cost per 100,000 btu of the cheap pellets is $1.21. Cost per 100,000 btu of the higher end pellets is $1.39. I do plan to buy a ton of high end pellets anyway and try them just to see if I'm missing something, but unless I am, the numbers speak for themselves...

I can see the advantage of high end pellets on a pellet stove that requires frequent cleaning of the burn pot or another piece of equipment that the reduced maintenence is worth something to the homeowner, but my goal is simply to heat my house the cheapest way possible without starting my chainsaws. That's the thought I have in mind as I design and test this project, so handling the cheap pellets gracefully is priority #1 (next to not burning the place down, of course).


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## Blevesque (Jan 31, 2012)

Treetop awesome job! Please keep us updated on how things are going and more pics when phase 2 unfolds. Where in Maine are you? Brian


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## treetopflyer (Feb 1, 2012)

Hi Brian,

Thanks. It's got a long way to go yet, but at this point, it's been very reliable and it loves the cheap pellets too. I'm in Lyman, that's between Sanford and Biddeford.

Mark


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## jbrown9709 (Feb 4, 2012)

Hi,  Awesome work.  I've done something somewhat similar.  in 2008, I built a biomass outdoor boiler using many of the same principles you are.  Every year since, I've learned a few things, and by now, mid 4th season, I'm down to 0 equipment failures so far this year (down from weekly or more often during the first season.  My control system is built around a cheap ($130) self contained plc, programmed with ladder logic.  I also use a cad cell for a flame sensor.  My fuel is hazelnut shells (As mentioned by someone earlier in the thread, there is another shell burner on this forum burning shells directly in a Whitfield pellet stove.  I live in the same valley as she does.  In fact, I've patronized her business without even knowing who she is at the time)  Rather than igniting the fuel each burn, I use a mass refractory burn pot, so the fuel self ignites upon delivery.  The fuel is delivered from the hopper via 2 sequential augers.  For fire protection (added after a couple of almost hopper fires)  I use a snap switch (open on rise) on the second auger that shuts down everything but that auger.  This way, that auger sweeps any burning material away from the primary auger and dumps it in the fire pot, where it sits and smolders until the snap switch cools and everything reactivates.  So far, this has worked perfectly.  My plan is to add secondary fire protection in the form of a deluge system, as described above, but rather than using electrical components to control that, I plan to use fire sprinkler heads mounted in bungs welded to the primary auger tube.  This way, if a fire ever got through the secondary auger and to the primary auger, before it could travel to the hopper, it would heat up, and break open the sprinkler heads, dousing the fire in the primary auger tube.  This will work even in the event of power failure, but won't false trip in a power failure of other control system fault.)  Hope this provides some food for thought.  Good luck in your continued venture.


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## thecontrolguy (Feb 5, 2012)

jbrown9709 said:
			
		

> My plan is to add secondary fire protection in the form of a deluge system, as described above, but rather than using electrical components to control that, I plan to use fire sprinkler heads mounted in bungs welded to the primary auger tube.  This way, if a fire ever got through the secondary auger and to the primary auger, before it could travel to the hopper, it would heat up, and break open the sprinkler heads, dousing the fire in the primary auger tube.  This will work even in the event of power failure, but won't false trip in a power failure of other control system fault.)  Hope this provides some food for thought.  Good luck in your continued venture.



Interesting, out of the box thinking.  I know there are MANY types of sprinkler heads, but I would recommend the types that have a flat circular disc on the sensing end that (usually) sits flush to the ceiling trim or finish material.  This would reduce or prevent any dust or bits getting rammed into the bung or sprinkler head.  They are called a "concealed pendent style".  Could you speak more as to what the type of head you are planning to use is?  Interested, I am.  Cheers.


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## joecool85 (Mar 6, 2012)

Wow, great thread, lots of great ideas.  I'm thinking about doing something similar with my old HB Smith boiler.


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## joecool85 (Mar 6, 2012)

I found a pellet boiler conversion burner made right here in the states: http://heutzpellets.com/burners.htm


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## treetopflyer (Mar 15, 2014)

Been a while since I posted on this project. The DIY conversion is still heating my home. I've rewritten the software for it a couple of times to better deal with short load calls from small zones and/or warmer days.  I found that with the firebrick burn pot I had to change the stones a couple times during the last heating season, so I made a new burn pot out of a slice of a cast iron cylinder liner from a truck engine. That solved the problem of the burnpot destroying itself over time and dropped my stack temp by about 50 degrees. It lights cleaner, the fire is better color and quieter and the boiler comes up to temp a little faster. 

I also added two stage firing. I'm adjusting the air on high fire and letting it run a little lean on low fire. It doesn't seen to bother it. Prototype #2 will have an air damper operated by a solenoid coil to allow ait setting adjustment on both firing rates.  I'm feeding about 13.5 lb/hr on high fire and about 8 lb/hr on low fire. It helps a great deal with light loads. Reduces short cycles a lot. I hung an aquastat on the supply manifold on the boiler and as the temp approaches high limit it kicks down to low fire. 

The pellet shortage up here in Maine has been a problem recently. My house isn't the tightest construction and it normally went through 1200 - 1400 gallons of fuel oil. I find that a ton of pellets equals about 120 gallons of #2 fuel oil, so I still need a lot of pellets. Pretty hard to deal with when the stores that do have them impose a 10 bag a day limit. If I can find pellets, I have to go as many days in a row as I can until they run out.

The bulk delivery guys have not been affected by the shortage. They have bulk contracts with the mills and it appears that they have first dibs on the supply. We're building a 4 ton stick built hopper in the garage this weekend. The truck is coming Tuesday to start us off with 2 tons and see how it works. It's a little more expensive buying bulk, but in my opinion, worth every cent of it just because I don't have to deal with unloading and stacking bags. The going rate here is $249 a ton delivered. I used to get pellets at Walmart and Home Depot for $209.00 a ton.

They use 4" camlock fittings to connect the truck. These are ordinary trash pump fittings available everywhere. The truck is scheduled for Tue morning delivery.  For now, I'm still going to lug pellets from the storage hopper to the day hopper in 5 gallon buckets, but I'm exploring pneumatic transfers now to see if it's practical to set this up to fill my day hopper.


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## Hoot23 (Mar 18, 2014)

Very cool setup. My father-in-law would be really interested in this. He has a Biasi wood/coal burner that he would like to convert to a pellet burner.


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