Winter is coming…and I am getting tired of wrenching on my rigs with gloves, a coat, and hat.  I assume there are quite a few gearheads out there in the same boat as I am; access to lots of old oil, not a lot of access to $$, and willing to build something cool to produce heat.  I just finished converting an oil furnace to run on waste oil so I thought I would share it. 

Cost is the main reason I decided to do this conversion.  With propane at almost $3 per gallon and home heating oil between $3 and $4 per gallon, heating my shop was going to be expensive.  My neighbor spends over $2000 each winter in heating oil to keep his house warm.  I wanted to heat for free; and I have access to an unlimited supply of waste motor oil, and about 5 gallons of vegetable oil per week.  Start to finish, this project cost me around $600 and took me about 40 hours.  I did manage to do some scrounging and got quite a bit of stuff for free.  However, I did waste some $$ on some ideas that didn’t work out. 

I need to give some credit to the members of the altfuelfurnace group in the Yahoo groups.  I wouldn’t have attempted this conversion without first reading the info there.

This write-up is intended to demonstrate how I converted my furnace to run on waste oil; it isn’t supposed to give you a detailed step-by-step conversion process.  If you’re going to attempt this conversion some basic mechanical skills, some good tools, a GOOD understanding of electrical systems, some patience, and a willingness to experiment are necessary.  I’ll answer any questions to the best of my ability.  I went through lots of ideas and alternatives before I settled on my final design.  I’m listing the steps I took and the parts I used in my conversion; but feel free to be innovative!  I’m sure somebody can improve on my design somehow.  I believe that the Beckett burner I used is also used in boilers; so this could also be used for in-floor radiant heat, hot-water radiator type heaters, or hydroponic furnaces.  A cart could also be built that holds the furnace and a primary oil tank, making this a portable high-capacity heater that you could roll to wherever heat was needed (although exhaust venting would still be necessary).

I don’t assume any kind of responsibility or liability for what you do in your shop.  Keep in mind that you are working with flammable liquid and high voltage.  If you set your house, shop, garage, or self on fire I’m truly sorry but it’s not my fault.  I also know that the EPA prohibits the use of waste oil for heating your home (although it is permitted for heating a garage or shop).  I have no idea how this would be enforced.  I don’t know of any other laws, rules, statutes, etc. involving the use of waste oil for heating so it is up to you to decide if it is legal. 

Suppliers:  Everything for this conversion can be purchased from your local hardware store, and the following internet sites:
McMaster-Carr www.mcmaster.com
Ebay www.ebay.com
Surplus Center www.surpluscenter.com
I would provide part numbers but since most of the items were purchased off of ebay and surplus center, they won’t be any good in a few weeks anyway. 

Principles of operation:  The basic idea of this kit is to preheat the oil before igniting it, and more finely atomizing it.  The preheating is done with a cartridge heater and temperature controller, and the atomizing is done with a siphon nozzle and compressed air.  To operate properly, the oil supplied to the siphon nozzle must be at a constant level below the nozzle.  To make the firing rate more consistent, it also helps to keep this oil at a constant temperature.  To accomplish this, I built a small “siphon tankâ€? next to the furnace that holds and preheats the oil.  When the temperature in my shop drops below the set point, the thermostat decides to turn on the furnace (this is a normal wall stat like you would see in a house).  It turns on power to 2 digital temperature controllers; one heats oil in the siphon tank. This tank is a small tank that is level controlled by a float switch and keeps oil level 2" below the nozzle center line.  The other controller heats the nozzle block.  Once both heaters have reached their setpoints, they complete the circuit on the “TTâ€? terminals on the primary safety.  This turns on the igniter, starts the blower motor, and opens the air solenoid.  The igniter provides a continuous spark just in front of the nozzle.  The compressed air flows through the siphon nozzle which pulls oil from the tank and finely atomizes it.  The safety will continue to run the burner for 45 seconds during the startup. I installed a cadmium sulfide flame detector in the blast tube; if at the end of the 45 seconds no flame is detected (or if it goes out while running) then it shuts the burner down for a minute or so, then repeats the ignition sequence.  If the burner doesn’t light during the 45 seconds, the safety “locks outâ€? and must be reset before the furnace will operate.

I consider myself quite mechanically inclined but have never worked with this type of furnace before; I would have saved a few hours of web mining if I had found a simple vocabulary list like this:
•   Igniter:  The black box on top of the burner that provides the spark for lighting the fuel
•   Primary Safety:  The control on top of the burner that monitors the burner and turns it off if the flame goes out.  Mine had 4 terminals; 2 “Tâ€? terminals (these need to be shorted together for the burner to run, comes in handy for keeping the burner off until the heaters are up to operating temperature) and 2 “Fâ€? terminals (these take an input from a cadmium sulfide flame detector, which makes sure the burner doesn’t go out)
•   Retention head:  This is the turbine-looking piece at the end of the burner where the flame comes out; it is used to direct air into the atomized fuel.

Step one:  Obtain a used oil furnace (or just the burner, if you already have an oil furnace).  It needs to be a Beckett burner.  I used a Beckett AF series in a 75k BTU Olsen downdraft furnace.  I found that, with a little patience, good working used furnaces can be purchased for cheap ($150 or so) on craigslist.  Usually, the people selling the furnace are also selling their oil tank to go along with it.  My local heating contractor also provided me with some free furnaces that they removed from homes, although I didn’t use any of them because they were all broken or worn out.  I tested it on diesel just to make sure the burner and fan were in working condition before I started.  I also got familiar with how the burner operated under different conditions (like when the fuel source was removed), and I paid particular attention to how the flame looked inside of the combustion chamber so that I could tune the burner to match this after the conversion.  My furnace also had a 24v transformer and relay used for the thermostat already installed (this was useful for switching the power to the burner).  It also had a fan thermostat (turns on the blower when the temperature reaches the setpoint, and turns the burner off if the temperature gets too high).

Step two:  Obtain all of the parts needed for the burner conversion.  I’ve listed the major parts below; things like wire, solder, crimp terminals, vent piping, tubing, brass fittings, etc. are not listed. 

1.   Pre-heater cartridge kit.  This is a kit sold on Ebay by ckep1.  He sells 2 kits; the first includes a machined aluminum block for holding the siphon nozzle, the nozzle itself, and the cartridge heater.  The second kit adds a temperature controller with thermocouple, a relay, and a flame retention head.  The heater block is the key part here; it is the one part that would be most difficult to come up with and I haven’t found anything else similar to it. 
2.   Temperature controller:  You need to get 2 of them (one if you get one with the above kit).  One is for the nozzle block heater, and the other is for the siphon tank heater.   I bought mine for $39 each on ebay.  Search for PID temperature controller.  Make sure you get them with a thermocouple (this is what senses the temperature).  I did find some 2-channel controllers, but they were more than 3 times the price of the TGC controllers so it was cheaper to just buy 2 single channel ones.
3.   Flame retention head:  You can get one with the kit in number one, or build your own.  It is pretty easy with a bit of 24GA stainless steel and some tin snips and a welder.  This is necessary to provide enough air to fully burn the atomized oil.
4.   110v SPST relay, 10A minimum:  This is necessary for the temperature controller to operate the cartridge heater in the nozzle block. 
5.   24V SPST relay, 15A minimum: for the immersion heater on the siphon tank
6.   24V DPDT relay, 15A minimum:  For the float switch in the siphon tank.  Controls the transfer pump, and ensures the tank is full before turning on the immersion heater.
7.   24V transformer:  for control voltages for the float switch and thermostat.  My furnace came with one already installed
8.   Â¼â€? soft copper refer line; used for the oil supply line.
9.   You will need some flare ends and other misc. fittings.
10.   Air regulator with a gauge, capable of 0-30 PSI
11.   Air solenoid valve with 110V coil
12.   Some 1â€? round steel bar stock (I used this for making weld-in ¼â€? NPT fittings)
13.    ¼â€? brass breather vent (vent for the siphon tank)  I used this one from McMaster-Carr: 4450K2
14.   Float switch (to control oil level in the tank)  I used this one from McMaster-Carr: 48095K61
15.   Petcock drain with ¼â€? NPT fitting
16.   Immersion heater element; I found a 1200W 120v hot water heater element with 1â€? NPT threads at my local Home Depot for about $5.  I also tried a block heater I bought off of ebay for about $10, but it took too long to bring the oil up to temperature.

Assembling the burner is fairly straightforward, and takes a few hours.  Basically, these are the required steps:
•   Replace the Beckett retention head with the new one
•   Put the nozzle and the thermocouple in the block heater
•   Remove the “Jâ€? tube.  It will be used as the air supply tube for the nozzle block.  Measure the length necessary to place the nozzle flush with the opening in the retention head, and cut the J-tube so that it is about 3/8â€? longer than the back of the nozzle block
•   Use a 1/8â€? NPT die to cut threads on the J tube and thread it into the back of the nozzle block.  The end of the J-tube I had used 45 degree flare; my local hardware store didn’t have any adapters to go from ¼â€? flare to NPT, so I brazed a flared tubing end to a female 1/8â€? NPT coupler to make my own adapter.
•   Run ¼â€? copper line from the back of the nozzle block out the side of the burner, underneath the igniter.  Where you run this line will depend on your furnace design; see my pics for how I ran mine.  This line will be under a vacuum, and if your fittings leak the burner won’t run right.  So it is important that all connections be leak free.  It has been my experience with past projects that compression fittings will leak after they’ve been tightened and loosened once; you’re better off to buy the tools (they’re cheap) for doing flare fittings. 
•   Run the line for the thermocouple into the box under the primary safety.   
•   Move the flame detector somewhere that it can see the flame.  I moved mine to the side of the blast tube and ran the wire with the thermocouple cable.
•   When you close the igniter box, make sure it makes contact with the leads.  Mine didn’t…so I welded a few inches of 3/16â€? steel rod to the back of the rods.  You could just use some allthread though…and I’ve been told that heating shops carry longer rods.
•   Remove the oil pump from the burner, and pull out the coupler from inside of the burner fan (this is the parts that drives the oil pump).  The pump will not be used, but must be reinstalled to allow the air adjustment to work.
•   Wire up the temperature controller; mine had a wiring diagram on a sticker on the side.  It’s pretty straightforward; 110v power goes to 2 terminals (this power should come from the power to the primary safety; it is switched on by the thermostat, described in following steps), the thermocouple goes to 2 terminals, and the output contacts switch power to the relay for the cartridge heater.  I left the relay in the box under the primary safety (looks cleaner than mounting it elsewhere in the furnace).  The alarm contacts go to the “Tâ€? terminals on the primary safety.  I set my temp controller to 180 degrees, and set the alarm to -15 (so the alarm contacts close at 165 degrees).  When the alarm contacts close, this completes the circuit across the TT terminals and starts the burner.
•   Adjust the pressure regulator to roughly 15 PSI and plumb it into the burner
•   Plumb the air solenoid in line with the regulator. 
•   Wire the air solenoid to the power output from the primary safety.  This means that whenever the safety turns on the burner motor and igniter, it also opens up the air solenoid (and, in turn, starts oil flow)

I tested my burner on the bench with cold oil; found that its performance on the bench isn’t the same as its performance when installed inside of the combustion chamber.  I think that the heat inside the chamber helps burn the fuel.  My flame was a little inconsistent and tended to go out unless I heated the fuel line with a propane torch.  At any rate, it is good to test it on the bench to make sure all of the systems work right.  This is a good time to adjust the igniter contacts too.  I found that with roughly 30 minutes of testing EVERYTHING in the vicinity of the burner had a thin coating of oil on it.  If I do this again, I won’t run my burner inside a building, or even near a building, car, or anything else that I don’t want an oily film on.

I installed my burner back in my furnace, and cut a couple of holes in the side of the furnace for the temp controllers.  The power to the primary safety and both temperature controllers comes from a relay inside of the furnace that is switched by a wall thermostat. 

Next, I put together my siphon tank.  I built mine out of 11GA (1/8â€?) steel 6â€? x 6â€? x 12â€?.  It holds just under 2 gallons of oil.  You could use any small tank though…maybe even a small compressed air tank would work.
•   I made several weld-in ¼â€? NPT fittings by cutting roughly 1â€? long sections out of some 1â€? round bar and tapping them with a ¼â€? NPT tap.  I also made a 1/8â€? NPT fitting the same way.
•   I put a drain in the bottom (assuming that water, sludge, or other junk will tend to accumulate in the bottom of it).   
•   I welded a piece of ½â€?steel round bar to the inside (about ¾â€? long), and then drilled and tapped it for the thermocouple. 
•   I made a large opening in the top, in case I had to clean the inside.  A lid goes over this opening and gets fastened into place with 4 screws (to keep bugs and other debris out).
•   I cut a 1â€? black steel pipe coupler in half, and welded it to the side of the tank near the bottom.  This is where the heater element screws in.
•   I put a brass breather vent on the top of the tank (keeps the tank at atmospheric pressure…necessary for proper siphoning)
•   I put a ¼â€? NPT “fill portâ€? in the side of the tank near the top.  This is where oil is pumped into the tank, when requested by the float switch.
•   I put the float switch in the top of the tank; the leads pass through the 1/8â€? fitting that the float is screwed into.  This float switch serves 2 purposes; it prevents the immersion heater from turning on unless the tank is full (heater elements tend to melt when they aren’t covered with a liquid).  It also sends a signal to my transfer pump to refill the siphon tank.
•   I made a pick-up tube.  Basically, I made a double-long weld in fitting, with each side tapped with ¼â€? NPT.  On the inside of the tank is a short copper line that picks up oil from the center of the tank.  On the outside, the fuel line goes into the burner.
•   Power for the immersion heater comes from the second temperature controller.  It is wired similar to the one for the nozzle block; 110v power goes to 2 terminals (this power should come from the power to the primary safety which is switched on by the thermostat), the thermocouple goes to 2 terminals, and the output contacts switch power to the relay for the immersion heater (this power runs through the NC contacts on the relay for the float switch; so when the level drops in the tank, the float switch energizes a relay, which opens contacts to the heater relay, preventing the heater from turning on if level is low in the tank).  My heater is 1200 watts (roughly 10 amps) so I ran dedicated power from the main junction box inside of the furnace to this relay.  The alarm contacts go in series with the other temperature controller.  The idea here is that BOTH temperature controllers need to be at their setpoints before completing the circuit to the “TTâ€? terminals on the primary safety.  I set my temp controller to 100 degrees, and set the alarm to -10 (so the alarm contacts close at 90 degrees). 
•   The tank needs to be positioned so that the oil level is maintained a couple of inches below the siphon nozzle.  Set the tank too high and the nozzle will continually drip oil even when the burner is off.  Set it too low and the burner will be starved for oil.

At this point you can run the furnace; I just topped off my siphon tank, and turned everything on.  Here is what I learned: 
•   The nozzle block takes about 1 minute to heat up.  It cycles quite frequently
•   The siphon tank takes about 5 minutes to heat up the first time; then it cycles on for a minute or so about once per hour.
•   My furnace uses about ¾ gallon per hour
•   It runs great on my own blend of about 70% 15W 40, 20% 10W 30, 8% 85W 140, and 2% ATF, PS fluid, and other misc petroleum products.
•   It still runs fine on diesel, but I need to turn off the heaters or it runs too hot.
•   It doesn’t run well on straight gear oil…it is too thick for the siphon nozzle. It might work if I ran a higher temperature in the siphon tank, but I haven’t tried it yet
•   It runs too hot on straight Kubota UDT hydrostatic fluid.
•   The flame height was best with the air regulator set to about 17 PSI
•   The combustion air vent on the side of the burner needs to be almost completely closed; I’m sure this is because of all of the air introduced by the air compressor
•   When first igniting, there is a short puff of smoke.  After about 30 seconds, there is no smoke and no smell.  It burns quite cleanly. 
•   Burning oil motor oil does result in some soot buildup. It looks like I’ll need to clean the combustion chamber after about 100 hours of use. 
•   It is important to make sure the oil in the siphon tank is clean.  The nozzle orifice is small and will easily clog with even small debris. 
•   I have a rather large uninsulated shop (1500 sq. ft.).  The furnace takes about 30 minutes to heat it up from freezing to about 60 degrees. 
•   I didn’t try this, but DON’T try to run gasoline, alcohol, or other potentially explosive fuel in this burner. 

If so desired, the furnace can be run indefinitely in this state.  If the siphon tank was built to hold 4 or 5 gallons it could run all day without a refill (although a larger tank will require longer to heat up when starting the furnace).  However, I wanted mine to be completely automatic, and I wanted the convenience of a large oil storage tank.  So, here are the steps I took to plumb in this tank:

I bought all of the parts I needed for my tank:
•   I bought a 250 gallon home heating oil tank.  Mine came with a vent, fill cap, and a level gauge.
•   I already had a small 120V centrifugal pump; it was a cheap Harbor Freight clear water pump.  However, I’ve discovered that it will pump waste oil.  Since it only runs for a few seconds at a time (the deadband on my float switch causes the pump to move about 1 cup of oil before shutting back off) it seems to handle the thicker fluid just fine.  If it dies, I’ll buy a waste oil transfer pump (gear pump) that is more suited to transferring waste oil.
•   I bought a large filter/water separator from my local Coastal Farm and Ranch (similar to Tractor Supply Company).  It was designed for the fuel transfer tanks that go in the bed of a pickup.  It has a clear sight bowl and 1â€? NPT fittings.  I figured this would be useful for the occasional oil with water mixed in.
•   3/8â€? soft copper refer line
•   Misc brass fittings and flare ends, whatever is necessary to plumb in your tank, the pump, and the filter

Next, I plumbed and wire the pump and filter setup:
•   Again, I used flare fittings at all of my connection points. 
•   The pump is controlled by a relay that is controlled by the float switch in the siphon tank.  This is the same relay that I used as the safety for the heater element (except that I used the NO contacts to control the pump).  So, when the level drops in the tank, the float switch contact closes, energizing the relay.  The NC contacts on the relay open, preventing the immersion heater from turning on.  The NO contacts close, turning on the transfer pump.

Below are a few pictures of my setup and of the burner conversion, and a video of the burner in operation

CLICK HERE for a video of the burner being tested on my bench

Here are a few pictures of the burner before the conversion:










Here is a pic of the Beckett retention head, and a pic of the new retention head:






This is a pic of the parts I used for the burner conversion:




Here are a couple of pics of the nozzle block, and the fuel line and cable routing:






The burner is completed:




Three pics of the burner being tested on the bench.  It is running on 15W 40 that I just drained from my truck, and the oil is unheated so the flame is a little smaller than it is with preheated oil:








And a few pics of the furnace installed in my shop (the cover is removed so you can see all of the components):

very nice writeup. had a dealership i use to work at had an old converted oil heater up in the roof straight plumbed into the waste oil tank. definitely took the chill off in the morning

very nice writeup. had a dealership i use to work at had an old converted oil heater up in the roof straight plumbed into the waste oil tank. definitely took the chill off in the morning

Thanks!  There's nothing like working in a warm shop on a cold rainy (or snowy) day...

wow man that was a great right up. how is the smell?

my work uses the waste oil and it has a certain smell some guys cant get use too.

wow man that was a great right up. how is the smell?

my work uses the waste oil and it has a certain smell some guys cant get use too.

When the furnace first ignites, there's a small puff of smoke (outside my shop) and a light burnt oil smell (smells like an old farm truck).  After that initial startup (maybe a few seconds), there is no smell and no smoke at all.  I haven't climbed up on my roof and directly smelled the chimney, but there is nothing detectable on the ground. 

sweet def thinking about doing that one day. just need a garage first lol

Great write up and excellent detail, Thanks!  BTW, your shop would stay a lot warmer/ cooler with some insulation (I'm sure you already know that.) I did mine top to bottom when I moved in, and I can keep cool as a cucumber wiath the ac in the summer and toasty warm with propane heat in the winter. The insulation saves quite a bit of energy too.