List of suggested oil engineers tools (by no means definitive)
I only carry one type of flexi hose, the one HWOS calls BIO3. If I find a different one on, I change the fittings to suit the BIO3 hose. I have found the black long life hoses degrade rapidly so only fit the Bio ones. I don't see the point of carrying loads of different ended hoses. In all the time I have been doing boilers I have only ever come across 2 boilers which this hose did not fit and needed an elbow at the opposite end to the pump because of shortage of space.
I recommend that everyone gets into the habit of using flared fittings as opposed to compressions. The best price seems to be HWOS or BES
Combustion analyser and printer (I scrounge till rolls from my local pub for it as one lasts ages and I'd never get through a full box of them)
Smoke pump and papers
Pressure and vacuum gauge set
Fuel priming pump (one from an automotive supplier is adequate) and rubber hose that will fit on the end.
Bearing puller for removing fans and motor bearings (long narrow arm type which will fit onto fan mounts and in tight spaces)
couple of pairs of 6202RS bearings (from Ebay - but only get good branded ones, SKF, NTC etc) You'll know when the bearings are worn as the burner motor will make a rumbling / whining noise. You can also purchase from an automotive supplier as they are the same as alternator bearings.
Pump drive couplings from HWOS
Selection of nipples, elbows, couplings etc from the fittings page at HWOS I only ever use flared fittings now, never compressions as they are less reliable (if using compressions a pipe insert must be used)
Pipe flaring tool
OFTEC forms - servicing and commissioning, oil storage risk assessment, installation
One of those magnetic pickup tools which looks like a radio aerial with a magnet on the end
1/4" ratchet set and extension pieces (get a good quality set such as Britool)
T handle long reach hex set
Screwdriver handled socket driver
glass rope and glass rope adhesive
STAG B jointing compound (prefer this to Heldite another post mentioned as Heldite is awful to get off your fingers etc)
PTFE tape (normal and gas tite (yellow spool))
rolls of 10mm and 8mm copper pipe (white plastic coated) and roll of uncoated
spare 3m 65 and 90 degreesC Teddington KBB fire valves (you can get more of different sizes as you go on) 1.5m is too small for many sites.
GOOD selection of nozzles (from 0.50 to 1.0 USgall/h - larger ones you won't come across often and can order them as required. Get just kerosene ones to begin with (ES & EH). Some boilers will specify W nozzles you can buy as and when on next day delivery)
Selection of steel nuts for when you loose some behind the back of a boiler so you don't need to spend ages looking for them.
Heat proof gloves for dismantling hot combustion chambers (I use welders gloves)
disposable vinyl gloves like the dentist uses
Barrier cream
Scrub hand cleaner (plastic microbead free please)
Hand cream
One of each of the cleaning brushes that HWOS do
Container to put waste oil into when cleaning out filters etc
Spare filter elements (just get the two Crossland ones to begin with)
Vacuum cleaner and spare bags (I use an old VAX cleaner but any will do)
Dust sheets
Kneeling mat or Kneepads (a MUST HAVE!)
Tub of fire cement
Tube of heatseal silicone and gun
Multimeter
Spare 3 amp fuses (a lot of boilers just have 13 amp fitted so should be changed)
Boiler manufacturers literature to show to customers when persuading them to change to a new boiler.
long 18/24mm drill but for drillling holes through walls for oil lines / fire valve capillaries
Electricians round trunking for sleeving holes for fire valve capillaries
Parts organiser boxes for all your fittings
Nozzle box
Set of flat, pozi and philips screwdrivers
8mm copper pipe and fittings for where you have a tank lower than the boiler (lot of people post problems on here caused by too large diameter pipe where tank is lower than boiler - always follow the table in the OFTEC book!)
Set of combination spanners from 6mm up to 21mm and inlcuding ALL the inbetween sizes
Scraper (paint scraper)
Selection of metric machine screws (probably be able to get an assortment box from Toolstation these days)
Torch (head torches are useful)
Tape measure
Circlip pliers
pump pliers
Standard pliers/nippers
Set of adjustable spanners
Selection of brass bushes, 3/8 to 1/4, 1/2 to 1/4 and 1/2 to 3/8 for example
Mini pipe bender
Round profile drift for reshaping deformed pipe ends.
Small flat, rat tail and half round files
Set of T handled Torx drivers
Selection of o rings including 13mm ID x 4mm for Sika flow switches
Spare seal kits for BFP and Riello type fuel pumps
Selection of glass rope seal (14mm is the most commonly used) Do not bother with replacement silicone gaskets for Trianco Eurostar boilers but replace with glass rope)
Also I carry a selection of 
