First Isolate all electrical supplies involved. then remove the small grub screw at the top of the unit and gently lower the cover down.
After removing the cover remove the wiring for the terminals taking note of these positions.
Remove the two retaining screw holding the unit to the wall and remove the unit.
Then install the new unit , rewire and test.
In private properties it is recommended to have gas appliances serviced annually and if the property is rented it is a legal requirement to carry out an landlord gas safety inspection every twelve calender months.
A modern high efficiency boiler could reduce your fuels bills by up to £ 300 a year. The modern condensing boilers are highly efficient because they recycle wasted heat into energy so are not only better for the environment but also save you money.
Most system run between 1 – 1.5 bar