EKO 40 Wood / Waste Oil Hybrid

[hartkem]

I know you wood burning purists are probably not going to like this post but that's OK. I travel out every week and I am gone for three days and my wife is not willing to load the boiler. I got tired of coming back to my system at 120 degrees and spend an entire load of wood getting it back up to temp again. I only have 500 gallons of storage in my basement and my EKO is in an outbuilding so it doesn't last long when I leave. I have cut my propane use way down but still buy about 500 gallons a year. I was wanting a new project to have some fun with so I started researching waste oil heaters and have successfully converted a Beckett AFG fuel oil burner to run waste oil with some parts from CK burners.com and parts from McMaster carr. I then built an exact copy of the lower door of my EKO and cut a hole in it to mount the boiler on. I removed the lower U bricks and added some fire brick against the back and side walls for extra protection. I have 1000 gallons of free oil on hand. Last night I fired it up for the first time for about 45 minutes. It only raised the water temp from 75 to 111 degrees. I still have to integrate all the controls into the EKO boiler using some DPDT switches and relays. My plan is to burn wood when I am home then simply lift the door off and slide on the waste oil door and switch it on. Then remove the waste oil door when I return. Shouldn't take any long than starting a fire with the boiler cold and feeding it up to temp plus it saves me 3 days of propane a week. My biggest concern is heat transfer efficiency.

 

[Fred61]

As I was reading your text I questioned how you were able to place firebrick against the back wall without blocking the tubes. Could that be your "efficiency" problem?

 

[hartkem]

Fred,

The bricks are spaced away from both the back and side wall and don't go all the way up so flue gases have several areas to get around them. I don't know that I have a problem I just thought it would heat up faster. Since there isn't the radiant coming off a load of wood in the upper chamber that is probably the reason. I did cycle the circ pump on a few times to see if maybe I had hot spots but the temp didn't really change much so that's probably a good thing. I'll learn much more in time and hopefully this won't all be a waste of money. I have about $900 in the oil add on.

 

[hartkem]

A few more pictures. Sorry these a screenshots of my phone to reduce file size.

 

[stee6043]

I wonder if you'd be far better off porting this thing through the upper door vs the lower. Do what you already did but on the upper door this time, close the bypass when the oil burner is on and let it exhaust through the upper chamber, down the nozzle and up the backside like it would do with wood. I think you're limited in your exposure to the water jacket by using the lower door....but perhaps I'm not imagining this correctly.

Any idea how much oil you'll go through? Pretty neat concept though I would not want to be a neighbor within a quarter mile of you...I've smelled waste oil burners and....yuck.

 

[hartkem]

stee,

I was thinking the same thing regarding putting the burner in the upper chamber for more exposure to the water after I already built the bottom door. My reasoning for the bottom chamber was that it was designed for the high temperature of the wood gasification flame and wasn't so sure about the upper chamber. I also was unsure of the length of the flame on the converted gun but after running it the flame isn't as long as I thought at less than 14" so hitting the back wall of the upper chamber wouldn't be an issue. I want to be easily able to switch between wood and oil. My neighbors are approximately 1000' away. I ran it for 30 minutes last night and it has no visible smoke from the stack. You could smell it close to my outbuilding and it doesn't smell as good as wood however I never really smelled it at my house which is about 200' away and there was zero wind. The prevailing wind will be blowing away from my house. I work in the automotive field so I have access to a 5 gas combustion analyzer that I plan to dial this thing in with for best burn efficiency and lowest emissions as possible. It really burns relatively clean the way it is. Maybe I'll get lucky and the upper and lower door are the same size and I can simply move it to the upper chamber for testing. I would love more input on putting the burner in the upper chamber from you guys. As far as oil usage, I'm banking on about 500 gal. a season since that's approximately the amount of propane I use but waste oil has more BTU content but between being in the outbuilding and the thermopex pipe loss it probably evens out.

 

[stee6043]

You'll find that the upper door is quite a bit bigger.

Do you have any high temp probes? You could measure a wood fire in the upper chamber and compare that to the output of the oil gun. I suppose I'd also offset the gun to the lower portion of the door if you have a choice. Keep it away from the top of the boiler box, just in case.

 

[TCaldwell]

Very cool, do you have to keep the oil in the totes warm?

 

[TCaldwell]

What is the nozzle volume per hr, and what is the estimated btu output?

 

[hartkem]

The tanks outside do not need heated. A pump on the burner pulls the oil into a 55 gallon
Drum which absorbs some heat from the room. The gun has a 200 watt preheat Block inside that heats the oil to 160 before it is atomized through the siphon nozel. Oil usuage depends on air pressure adjustment. 5-15psi is typical. I've been told at 15 it can be as much as 200k btu an hour but I haven't confirmed this. I plan to not exceed the output of 120k since that's all the 40 was designed to do with wood. There is an electric element in the siphon tank that will come on during a cold start but this should'nt need to run much after the room is up to temp since most of the preheat should come from heat absorbed from the room. This element is set to keep the oil at 80 coming into the gun. Of course these temps may change a little as I dial it in.

 

[TCaldwell]

Are you using the draft inducer with the waste oil burner? I would think you could monitor flue temps to tune the best firing rate for that boilers hx capability.

 

[hartkem]

I'm not using the fan on the boiler at all when the oil is on. Last night I found out that the upper and lower doors are the same size on the EKO 40 so I can test the heat exchange in both spots.

 

[maple1]

Wonder if you should stack some fire brick up at the back of the firebox for the flame to hit, if you try it up top?

Interesting thread!

 

[hartkem]

I'm thinking of mounting something like this behind the door for the flame to blow into. The chamber pictured is for an oil furnace and the gun mounts to the front and heat escapes through the holes. If I move the gun to the upper chamber I would direct the holes towards the nozel opening. The benefit to these chambers is they heat up very very quickly and help with complete combustion by concentrating the heat around the atomized Fuel helping to combust all the fuel leaving the nozel $140 with shipping.

 

[brenndatomu]

Interesting thread...way to think outside the box.
Just a thought...does the EKO have a barometric damper on the fluepipe? Many wood burners run the baros at -0.04" to -0.06" WC...many oil furnaces are more like -0.03" WC...the heat would have a lot more transfer time with the latter...

 

[hartkem]

Well I've finished integrating the boiler controls into the oil side. With a flip of a switch I can go from wood to oil. I also decided I would run "efficiency" trials comparing the oil gun mounted to the lower door vs the upper. I just finished the lower door trial and was a little disappointed. First i valved off my storage tank so no heated water could leave the boiler. Then I manually plugged in my near boiler circulator so the water would circulate around the boiler inlet and outlet. I did this thinking I would have more even heat distribution in the water. I then ran the oil gun for one hour with a boiler starting temp of 75 degrees. At the end of the one hour the temp of the boiler was at 156 degrees. I also measured flue temps with a thermocouple inside the flue and got a max reading of 324F. I'm disappointed with the boiler temp increase but happy with the flue temp. I left the circulator run after shutting off the oil gun and the temp slowly kept rising. After 10 minutes it was up to 163F. Next step is to move the oil gun to the upper door, let the boiler cool off to 75 degrees and repeat the test with as close to the same conditions as possible.

The last picture is the junction block where I integrated all the electronics. The pid controller regulates a heater in the constant level tank that feeds the siphon nozel. Temp is set to hold the tank at 75F. Will really only be needed when I pull cold oil from outside tanks.

 

[Fred61]

After 18 years experience with gassers and having a Wood Gun with oil back-up I'm speculating that there is a huge difference in the temperature of the flame. Oil burner manufacturers have been trying for years to get the flame to burn blue.

 

[hartkem]

Well I just finished the trial for the upper chamber mounted gun. The temp reached 186F over the course of 1 hour from 73 degrees. My flue temp was max at 192. Seems the efficiency is quit a bit better however I had a lot of problems with draft. Smoke kept trying to come out all the Noke and crannies of the boiler. Even after 1 hour it seems the upper chamber was under pressure. This caused the boiler room to smell like waste oil smoke the entire burn and I had trouble getting the flame to start and stay going. Even though the effiency is quite a bit less I think I'm going to keep it in the bottom door for this season at least and see what happens with oil use. I didn't have any of those problems with it mounted in the bottom chamber.

 

[mlappin]

Slick setup. I use waste oil strictly in the shoulder seasons then switch over to all wood. Mine was a kit from Heco, have to manually light it, but once lit have no issues, and I have a high temp cutout so once the water is up to 192 degrees it shuts down. I have around 700 gallons of storage so I normally just do something akin to a batch burn every few days. Took me years to get all the waste oil we had around in 55 gallon drums burned up. Now I actually have to go and pick up some here and there if somebody offers a barrel full.


Where did you get the kit or instructions on how to do this? Might be something I’ll look into before our next vacation, father tends to forget to fill the wood boiler for me sometimes, wasn’t a issue before he got remarried and still lived with us, he forgot to fill, had a cold house to wake up to.

 

[hartkem]

I got the preheater block at ckburners.com. He provides instructions on how to assemble. If your mechanically inclined its not to hard to figure out.

 

[mlappin]

Thanks for the info, with the price of corn still in the basement this might be something I’ll look into, should be much cheaper than paying for gas or buying a commercial waste oil unit for next time we can take a vacation.

 

[TCaldwell]

Your door test result make perfect sense, as with the heat being in the upper chamber it becomes more difficult to establish a fluegas path through a downdraft design, hence out the nooks and crannies vs. the boiler hx tubes. The low flue temps were likely caused by low fluegas flow through the boiler, again I'd suggest a small amount of draft inducer.

 

[hondaracer2oo4]

Correct me if I am wrong but lower flue temp=less draft created which is causing your issues. If you just increase nozzle size for more gph that wil raise your flue temps since the boiler can't capture it all which will solve your draft issue.

 

[TCaldwell]

by putting the burner in the top door you created a heat trap, with little ability for the fluegas to gravity out, at least the bottom door install with the masonry nozzle above caused enough of a obstruction for the fluegas to travel past the hx tubes, if the above is correct I doubt more gpm with the upper door install would be better, I think it needs a little draft help to pull the flue gas through the boilers designed path

 

[salecker]

Slick setup. I use waste oil strictly in the shoulder seasons then switch over to all wood. Mine was a kit from Heco, have to manually light it, but once lit have no issues, and I have a high temp cutout so once the water is up to 192 degrees it shuts down. I have around 700 gallons of storage so I normally just do something akin to a batch burn every few days. Took me years to get all the waste oil we had around in 55 gallon drums burned up. Now I actually have to go and pick up some here and there if somebody offers a barrel full.
.

Try to find a cooking oil source.I have used it in my waste oil furnace.First tried mixing it with used oil.It mixed well and didn't separate after a year in the shop.so i tried a 25% mixture worked just like used oil.Last yaer i tried some straight and it worked fine.I have found that my furnace will go an extra 100 hrs or so without cleaning if i run cooking oil in the mix.
I have 90 barrels of cooking oil,it was delivered free,plus they took $1000 dollars off a loader i was buying from them.I havn't touched it yet.I figured i would use it last as no one can complain about stored cooking oil.