My miniture waste oil heater

Topic: My miniture waste oil heater (Read 49 times) previous topic - next topic

My miniture waste oil heater

May 11, 2026, 05:23:53 AM

Design goal:
- Minimal parts / complexity
- Readily and easily salvageable materials
- Simple easy to service design
- Flexibility of application, So atm it will be used on a wood burning cook stove to heat the house, but it will be very easy to mount to a boiler (I prefer secondary exchange for comfort and safety)

Utilizing Air atomizing siphon nozzle for the heavy oil with a 0.5mm Nozzle @ 14.5psi gauge, Ideally should be a 0.2mm nozzle.

The 0.5mm Nozzle at 14.5psig should make apx a little over 20,000 btu/h

Goal is to not use preheating, to save some energy, so I am using a gasoline waste oil mix, now you may ask doesn't that defeat the point? Well 16L gas makes 64L of fuel and gas is cheaper then diesel and used oil is generally free (It costs you time and effort to get it, but with careful planing and asking around every time you do a trip!)

Parts purchased:
Oil primary control - New
Nozzle Assembly - New
Regulator gauge assembly - New

Currently got body assembled and a refractory target end of the burn chamber. So now it is down to fine tuning the fuel mixture and secondary air mixture

Issues:
Internal flame tube is too small diameter for the nozzle it is 4" how ever should been ideally 7", rest of dimensions scaled accordingly

Now rest will be pics with some explanation.

Nozzle assembly as ordered from Amazon dot Ca, I modified it by adding the rivets as a centering shim and slide to make it easier to insert to the flame tube

Flame tube marked out and cut from a old 2.5lbs Strike first fire extinguisher shell. A fiber glass impregnated cardboard backer plate to secure the tube center

Flame tube welded to the fire tube (It's job is to ensure full combustion by vaporizing any larger droplets and guide the flame to the end of the outer chamber) that is the larger flange at the front from a 40lbs Amerex extinguisher shell, this will make clearer sense down the road. Yes I suck at stick welding, TIG been much more preferable for me!

The burner assembly is the removable element to facilitate cleaning and repairs down the road, so welding on the flange to form the lap seal with the main heater body

Test Fit

The fins serve 2 purposes, 1: is to center the tube in the main body, 2: to re-enforce the spin of the heated gasses to improve heat transfer

-Continues

Re: My miniture waste oil heater

Reply #1 – May 11, 2026, 05:34:11 AM

Part 2:

Checking sizes before moving on, yup all fits and clearances as intended

Lets get all the nasty burned off and test the basics! Yup, she's cooking!

Exhaust tube, made from same shell from the flame tube, weld is ground and some what smoothed for good gas flow.

Re: My miniture waste oil heater

Reply #2 – May 11, 2026, 05:39:12 AM

Part 3:

Here it starts to come together, those used to the old life style may see where it is going once you see this part!

This flange is what sits on the wood where the usual burner plate sits to securely lock it on the wood stove (that flange gap on the burner assembly will be dealt with!) When it will be used for a boiler that flange can be clamped on to a fabricated socket

Test fit, looking good

Re: My miniture waste oil heater

Reply #3 – May 11, 2026, 05:48:19 AM

Part 4 due to the lack of an edit button!

Sadly for some reason the secondary air bracket fabrication and test burns never saved properly but, this is the secondary air welded on. and a dusting of bbq paint for looks after much sanding.

Now the real question, what does the inside look like after 2L of nice nasty waste oil from a car and diesel power plant been run through it?

Pretty dam good apparently!

That is the looks of Success! Good clean burn, white ash means full combustion and nice even oxide formation means good mixing and even heat distribution.

Refractory target laid in, this will aid in combustion and extend the life of the rear of the burn chamber, this is where I am at, once this is cured I can start fine tuning the flame, this needs to be done with every batch of fuel that is made, so it pays off to mix very large batches! Now with a per-heater this whole mixing thing goes away, waste oil needs to be preheated to 80C for it to behave like diesel and nothing more than a spark is needed, but part of this was to side step that for now.

The electrical stuff will be a reply to this thread down the road.

Small remaining structural things is to add some bolts to press off the front for cleaning the body and servicing the refractory target, and an adjustable foot at the rear of the chamber, and possibly touch shield

Re: My miniture waste oil heater

Reply #4 – May 11, 2026, 05:54:44 AM

Well here it is, siting on its home for now where I can do all that pesky electrical and safety stuff out of the wind and rain!

Need to clean the area now that some serious energy will be produced. As expected too powerful with the 0.5mm nozzle, need to get a 0.2mm, can try a needle valve to choke it down.

All ready used it to peak the house up in temp, certainly fine tuning needed but for now it has performed as desired and intended, can't ask more then that!

Re: My miniture waste oil heater

Reply #5 – May 11, 2026, 12:05:25 PM

Question:
How much heating is coming off the exterior painted surface? Maybe a heat blanket/wrap to keep a bit more in?

Cool build!!

Cheers
Bruce S

Re: My miniture waste oil heater

Reply #6 – May 11, 2026, 07:13:34 PM

right now a ton, and that is desired in this unit as it is mostly air heating, second chamber will be made larger and fully insulated for the boiler.

Now I am working on a small heated carburetor from an old pot burner for it, as mixing gasoline in is getting tedious

I did the math and for 4L per hour I need 250 to 300w to ensure cold oil will be at proper temp.

Re: My miniture waste oil heater

Reply #7 – May 12, 2026, 03:59:16 AM

Guy I know in the next small town east of me used to burn waste oil... he got tired of nozzles plugging despite filtering the old oil, filter prices went way up... he put in an outdoor wood boiler instead. Less work since he has kids who cut wood for him. Most doesn't need splitting, just shove in a bunch of 4' long logs and let it go! Will burn 24 hours on a crammed full load. His neighbor doesn't like that though! Gets a wee bit heavy white smoke when throttled back and packed full.

Re: My miniture waste oil heater

Reply #8 – May 12, 2026, 04:30:02 AM

Quote from: MaryB – on May 12, 2026, 03:59:16 AM

Guy I know in the next small town east of me used to burn waste oil... he got tired of nozzles plugging despite filtering the old oil, filter prices went way up... he put in an outdoor wood boiler instead. Less work since he has kids who cut wood for him. Most doesn't need splitting, just shove in a bunch of 4' long logs and let it go! Will burn 24 hours on a crammed full load. His neighbor doesn't like that though! Gets a wee bit heavy white smoke when throttled back and packed full.

We have that too, gravity does the bulk of the filtering for you! where most go wrong is they try and run on the bulk tank, imo that is just for mixing and pre-settling, you want a small heated day tank, the heat causes the crap to fall out of suspension.

You drain sludge just before you fill it, then you filter the sludge, as for the feed filter you only get the reusable ones and have a couple spares, so just swap em as needed

It is a hands on venture and cleaning every month to 3 months depending on design, but once tuned, it just works.