I have installed MANY waste oil systems, heres the trick and secret to them, dont tell anyone....
"TWO OIL TANKS, and a 50 gallon drum".....
I run a pair of oil tanks to them, 1 for waste oil and 1 for #2 oil/K1 mix (20-1, so 200 ga of #2 10 ga of K1)...
Put a 50 ga drum on the side of the waste oil tank, with a pump and filter system in it, I use a dee zee pump, krane filter plate, with bf584 spin ons, its not cheap but its the last time you will mess with it, pipe it nice from the 50 gal drum through the pump and filters into the 275 tank. The 50 gallon drum should have a large funnel with a screen in it and your oil catch buckets (I am assuming you are using a tall lift type) should have pumps on them to pump it into the drum..
You have to run 1/2" copper from the waste oil tank to a fb8 filter and oversized check valve), then 3/8" with a couple loops in it with a fb4 filter to a Tee, then run 1/2" up to the burner, Dump your return line into the waste oil tank. (both tanks have to have vents in them and be tied)
So now the next part- care of the oil, Don't use anti frze or water, just oil, and gt your guys in the habit of wiping the oil pans off before cracking the bolts, try to get as little undercarriage dirt in the can as possible...
ONLY pump from the top half of the 50 ga drum, so this means you will run the dee zees pump pickup about 17" into the drum, you never pump it empty and always give it time to settle, the pump is fast and strong so it will pick up a lot of the oil off the bottom half you just dont want the bottom... so you wait until its almost full, then you run it for a minute, it will be half full and then do it again when its full again...
So that is about it, you want to keep your waste oil storage under 3/4" full, which shouldnt be an issue, and if you need more storage just add more drums of oil on drum dollies... The oil and #2/k1 mix will automatically mix pretty well, the trick is making the waste oil have little resistance and the clean oil having more- using small line, and putting some loops in the clean oil side, also you can use the firomatic valve to slow it down also... its a bit of an art, but its easy to tune once you get it going, the return line is going to be pushing into the waste oil tank (very little), and the check valve on the waste oils feed line will stop the clean oil from balancing in the waste oil tank, the waste oil will balance a bit in the clean oil tank but that is what you want...
I learned this method by trial and error, I have a customer in Mass that has 9 work bays, changes A LOT of oil (actually has 2 330 gallon storage tanks plus the system I outlined above), he heats the shop, offices, and a storage building next door all with waste oil...
He bought the systems from someone else, and installed them himself, called me in the middle of the first winter, and my guys fixed that thing 10 times, always gummed up, always going out in the middle of the winter. finally he called and said with the service charges it wasnt worth it, he was better off paying to get rid of the oil and using electric heat for what it was costing him...
SO I went there and started tinkering with it myself, I cam up with this system and it works perfectly, just clean the units once a year, I actually use globe valves and pressure gauges for his system, plus 2 oil reserve pump systems at the ceiling near the 2 larger units, he has 1 person in charge of it, one of the mechanics, he is the only one allowed to pump oil into it, and he pays attention, I kow they say you can have a bit of anti frz but its not worth the aggravation it causes, motor oil, hyd oil, etc is fine, just not water...
I know he ended up spending like $2000 in pumps, parts, (not counting my labor), but he says he is saving $3K a year even after buying the k1/oil mix.. He also said he doesnt dump the k1 all the time, but its working...
good luck, my advice is design it well, use pumps and dont dump, let the oil sit and the thick garbage on the bottom, just get rid of with the oil recycling program, its not worth the trouble of trying to burn it, get a wood stove and dump it on the wood if you dont want to recycle it, lol... That bottom couple inches of sludge, and the water is what causes all the head aches.
When tuning the mix, you only want a tiny bit of the clean #2 mix going in, use the firomatic like a globe valve, you will see just a tiny bit of clean oil, say 85% waste oil 15% #2, so if you burn 1000 ga of waste oil, you should only use 150 gallons of clean, the system I did for that garage only goes through about 1 tank of clean oil a year and he is heating a HUGE amount of space, for a small 4 bay garage, I would say 1 tank full will last 5 years, lol...
hope this helps..