I figured I'd share my project which isn't done yet. I'm making a boiler of sorts, which will burn waste oil.

 

My little garage is barely big enough for a go kart nevermind vehicles, so I removed both doors and built into walls. Once in a while it's nice to tinker and build things, so I picked up an oil furnace at a yard sale once, and used it for heat when needed. The garage isn't insulated (but will be soon now) but for the odd time I needed to do a project, it was easy enough to dump a few liters of diesel in a tank and fire it up. I tried a wood fireplace once, but oil is so much faster to get heat plus when I shut it off and go in theres not a fire still going.

Somewhere along the way, I decided to start mixing some waste engine oil in the fuel, more waste oil, eventually I had to pull the burner and adjust it to burn waste oil better.

Anyways, eventually, the combustion chamber had enough. Upon reading, thicker oil makes a tighter spray pattern and longer flame which ends up blasting against the combustion chamber and eventually wrecking it. This was not an instant problem so I had no idea it was an issue. Running 100% waste oil for hundreds of hours eventually did this.

 

This was a few weeks ago, burning waste oil. I've always been so impressed with how well the Beckett burner burns waste oil, that's why I've decided to utilize it for a boiler project. The exhaust is just heat waves in the air and doesn't smell at all.

 

This is a about a gallon sized jug I've used for years for a fuel tank. I would start the furnace and shut off with diesel, and run waste oil if I was in there for hours. It took about 15 minutes for diesel to go through the line and filter and pump.

 

After removing the Beckett burner from the furnace, it looks like the retention head has gotten pretty darn hot. If you've never seen one of these before, it's basically an air flow control plate that keeps the combustion close to the head.

 

So, since the burner works alright and the furnace was pooched, I decided why not build a boiler system and that way I can pipe heat to the house and save on the heating bill.





the fire box was made from 8x8" tubing that was 40" long and 1/4" thick.
the exhaust flues are 1.5x1.5" tubing 1/8" thick.
The plate used for the body is all 1/8" thick. It was a 6x12 sheet.

 

The 6 flue pipes come out the top of the tank, I have to make a collector to go to a 6 inch chimney pipe.

The tank is actually going to be filled with oil instead of water. It seemed like a way to avoid corrosion issues.
because it's going to be oil filled, special precautions needed to be taken to avoid a worse case scenario failure of the thermostat failing in the on position and running the burner and heating the tank way beyond safe levels.
So my plan is using 3 separate thermostats, 2 on the boiler tank, and one on the exhaust collector somewhere. This way all 3 thermostats need to be in the correct range for the thermostat wire to be connected and fire the burner. The chances of all 3 thermostats failing is so slim there's no point in thinking about it imho.
however, the fill tube on top will also be metal and route outside, if somehow the oil begins to vaporize it will vent outside.

 

A little note about designing things with safety in mind, i always like to think of failure modes. You can't ever eliminate 100% of a risk, but you can mitigate it hopefully with multiple safety systems.

For example, as i said I'll be using 3 thermostats. They are digital with "k" type thermo couple sensors and go from -40 to 999* c . 30 amp relays.
2 will be on the tank in separate locations with separate hold downs. They will be wired in series with the thermostat trigger wire for the burner so they both need to be in the heat demand position to fire it on.
The primary will be set to turn on at 180*f and off at 200*f. The second thermostat will be set to turn on at -40 and off at 220*f. This way, if it should overheat, it will not fire up again. ( unless it reaches -40 in the garage in which case the burner would never start anyways and shut off within 5 seconds.)

The thermostat on the exhaust will be set similar, on at -40 and off at (whatever the exhaust being too hot ends up being maybe 600*f) so if the exhaust overheats the system is disabled until it reaches 40 below.
Disconnecting the probe wires gives the same reading as 40 below.

So, for it to fail and "runaway", all 3 sensors or thermostats would need to fail, which realistically isn't likely.

On top of the temperature control system, the burner itself has an optical sensor which disables the burner if it runs and doesn't fire within about 5 seconds. That's standard equipment from Beckett so I'm assuming a fairly high quality.

 

Just showing how the Beckett burner will sit roughly.

I used water to test the tank for leaks, there was a few pinholes and a few spots where it got wet but didn't leak out. Over about 5 hours there was only a few drips on the ground. It proved very hard to weld over water pinholes. So I drained the water and welded up the worst, and the rest I'll repair once it's full of oil and hot. Welding over oil is actually way easier than water I've found. Plus oil doesn't cool as well as water so penetration should be better.
obviously the tank would be totally full to eliminate the chances of starting a fire inside.

 

This part will fit over the rectangular hole in the top of the boiler. It holds the heat exchanger and has a hole in the middle where I'll weld in the fill/vent tube which will run outside. This will maybe come off once every year or 2 to suck any sludge from the bottom of the boiler that may have settled out of the oil.

this copper piping will circulate antifreeze through the hot oil to be used for radiators in the garage and house. The copper pipe is held in the still tubes by construction adhesive so the steel and copper doesn't touch and start reacting or corroding.

Maybe it's hard to notice in pictures but the fire flue tubes are in the back half of the boiler and this heat exchanger will sit in the front half. It reaches from the top to just above the fire box.

The actual boiler tank is 12 inches wide, 6 ft tall, and about 40 inches deep. So this heat exchanger would be roughly 5 ft tall.

 

This is a thing I made that hopefully helps. The fuel supply will flow from the tank, through this, then a filter assembly before the burner. I'm hoping this collects most of the junk so the filter lasts a long time.

I will also be filtering the oil with cloth or paper towel and other makeshift stuff before it going in the fuel tank. It will also sit before hand so I can drain off sediment and water, but this might work good as the oil will flow slow through this.

 

It's hard to see here it's a terrible picture, but this was an experiment where I crudely vented the furnace chimney exhaust up to a heat exchanger (old bus heater) and sucked the exhaust through it with a normal 84cfm bathroom fan and vented it outside using flexible pipe.
the point of the experiment was to prove or disprove if the heat exchanger could flow enough exhaust and coolant to let the furnace run and cool the exhaust enough to use light gauge vent pipe or even plastic, while capturing the waste heat into the hydronic system.
The experiment was a success! The fan kept enough draft to keep things running smooth. The exhaust temperature after the heat exchanger and fan was only 10 degrees warmer than the coolant leaving the heat exchanger. However, there are problems with this idea. First of all, a bathroom fan isn't rated for any elevated temperature, so to do this properly you would need a draft vent fan which is 300 bucks or more but meant for high temperatures.
also, a heat exchanger like this would be really hard to clean if it got built up with oil or dirt. If the burner ran perfect and lit instantly every time it would be fine, but theres always a little smoke when it fires up, plus there could be humidity and particulates in the gases that might clog it up eventually.


This is the little heat exchanger used in the experiment, yes the hoses are taped on that is how crude this was done.

 

So now I'm waiting for thermostats to come in mail, and ceramic wool to insulate the combustion chamber. The ceramic acts as a refractory and keeps the combustion hot and clean.

 

Day-um that's sum skills right there, send some of that heat to N.J. please...
That's a lot of sweating

 

its all been a lot of work actuallactually very annoying finding parts. Yesterday I drove 1.5 hours to home depot to but ceramic wool and they say it's only online not in store 🤬