no hot water from oil boiler?

im an oftec engineer.
your boilers water temp thermostat is faulty by the sound of it, and is available at any heating spares supplier. it comes with a capillary tube with sensor bulb, and the thermostat body. it has one nut behind the green dail (that pulls off) holding it in place, and insulated wire terminals pushed onto the spades on the rear of it.
simple job for an engineer.
Also get someone to run a hot tap, and listen for a definite 'click ' from the boiler as the tap is turned on/off...if no click, the flow switch is sticking.

mark properjob
February 2012