You can find good used waste oil burners around, for less than half the cost of new ones. I bought a decent used one 14 years ago off of one of the guys I worked with 14 years ago, and I'm still using it. He used it himself for 5 years or so, but, sold it for 2 reasons. It's a 110,000btu unit, and just wasn't big enough to heat his shop. The second reason, was because two of the heat exchanger tubes had burned through. He found a 350,000 unit, and sold me this one right. I have a buddy that does sheet metal work, that their shop did repairs like this. He built new heat exchanger tubes for me, and installed for $475. In my other shop, I'd go through 400 gallons of used oil, in an average year. It paid for itself the first year, compared to the HHO furnace I'd already had set up, and used in previous years. When HHO was 85 cents a gallon, it wasn't that big of a deal. When it got up around $2.00, I started looking for a cheaper source of heat.
There is some maintenance to them, usually twice a year, or every 750 hours of burn time. Being I turned mine on sometime in Oct., that usually meant sometime in Feb. I'd go out, and find the shop pretty cold. Within an hour, it was back up and running, once you get used to how to go about the clean-up.
I sold that place, and brought it with me to the present location. I also set up a wood/coal stove right beside it, that I fire when in the shop, and also, in case it happens to shut down, from a clogged nozzle, burner needs cleaned, etc. I finally learned to do a scheduled cleanup, sometime in Feb., to prevent a shut down. Wait for a fairly warm day, when not much is going on, and spend an hour doing the service, and you're good until Spring.
I built my own oil filtration system. I call it my luberfiner, after the ones used on trucks. I bought a new 30 gallon upright air compressor tank off of ebay locally, for cheap. I made a funnel out of the bottom of a water tank that holds approx. 8 gallons, and plumbed it into the top of the tank, with a 1" ball valve in between to shut the flow off, and allow me to pressurize the tank. Out of the bottom with 3/4" hydraulic hose, coming up to a convoluted type mesh filter. The furnace came with a #100 mesh filter. I bought a box of 20 #200 mesh filters on ebay, for like a buck apiece, and replaced the furnace filter, and put one in the filter head on my oil filtration tank. Out of the filtration head, I ran an approx. 5' long, 1/2" hydraulic hose, with ball valve, for a filler hose. I plumbed in a 1/4" air inlet, also with a ball valve. I fill the tank, close the valve on the inlet of the tank, then pressurize to about 30 psi, pushing oil through the filter, and into the tank. It would be a lot handier if the tank was horizontal, and held more, but it, what it is.
I store my used oil in HHO tanks I picked up, from people have converted to natural gas heat around here, just to get the out of their yard. The tanks were in a corner, of the other pole barn to keep them out of the weather. I will do the same here, once I get it set up. I have one outside at the moment, but no problem with water getting in. You may get a bit of water in some containers from people, especially in drums left outside. If you happen to get a bit in the big storage tank, and left to set a while in the summer, just crack the drain in late Fall, to purge it.
The worst problem to date came last year. A buddy of mine put used oil, in a Thompsons Waterproofing 5 gallon can, that was not completely empty. I questioned him at the time, but he assured me it was clean. He was wrong... The furnace shut down mid Jan. of last year, about 4 days after adding the oil he gave me to the furnace supply tank. Did a service, and it ran for 2 days, and shut down. I messed with it for 2 weeks of it doing this, and every time, there was a small gob of "something" in the nozzle, plugging it. In the meanwhile, I'd found that the reduction gears on the little motor that drives the supply pump were so worn, it would lock up occasionally. With the new motor installed, new inline check valve to prevent backflow from the above burner unit, it still shut down. After this cleanup, I watched inside the burner unit, and it was spewing little blobs out, like balls of fire, splatting on the end of the burner chamber. The light bulb finally came on. Small sphere's of the Thompson's, had squeezed through the mesh filters, and were in the tank. I purged the tank, into barrels, and added new used oil. Problem solved.
So, now what to do with 165 gallons of contaminated oil..?? Another simple fix... I had a spare HHO oil filter head I'd gotten at an auction in a box of "stuff", so added it beyond the mesh filter on my "refiner" tank. I bought a box of 100 HHO filters on ebay several years back, figuring I'd never have to buy any again, for 25 cents ea. I've pushed approx. 350 gallons of oil through it, and just changed that one out right after Christmas, when refining the oil I purged last year. No problems so far, so I'm satisfied it's doing the job I intended.
I haven't been out there yet, but it should be a toasty 64ｺ in there, as I type. I'll bump it up to about 68ｺ, and start the ole' coal stove, to help conserve oil. They are well worth it, if you don't mind a little maintenance, if you can buy one right. Most companies have the repair/service, &parts manuals available to copy, if the original doesn't come with one, if you get one used. The wiring schematics can be a little overwhelming at first, but just set and look at it, and trace it out. The rest is easy.
Actually, such a heat source would be great but, pretty sure installation would be expensive.
