Faulty Ravenheat condensing boiler?

Im amazed you paid him to fit parts that didnt solve the problem

Lets look at this problem logically

The CSI range has a combustion casing front cover held on by approx 13 screws which have to form an airtight seal in order to create a negative pressure inside the depression chamber so that the fan can activate the air pressure switch and start the ignition sequence

In simple english
Air tight cover -> fan -> aps -> boiler ignites

The guy you had out has already proved the aps works
By sucking on aps tube

If fan still rotates fast enough to activate aps & isnt sluggish
I would have to assume the depression chamber is defective in some way
ie no airtight seal

The depression chamber is constructed of pressed sheet metal & spot welded on the joints
These spot welded joints are known to fail after a while

Also the self tapping screws holding the front combustion casing cover may fail to grip securely (due to oversized holes in the sheet metal) & fail to create an airtight seal

There are ways of testing the airtightness of the depression chamber using a smoke bomb & a plastic bag over the flue creating a bellow effect & seeing where smoke emanates from failed joints

My guess is most gas engineers wont do this test as it is laborious & even if you do find a joint failure on the depression chamber the only solution is either depression chamber replacement (an absolute nightmare of a job) or more realistically a boiler replacement

If you are determined to keep this boiler i would recommend you contact ravenheat directly who could probably recommend a ravenheat repair specialist in your area

Asbestos
August 2017

Some similar threads here:

http://www.ukplumbersforums.co.uk/threads/help-please-with-ravenheat-csi-85.34324/

http://community.screwfix.com/threads/ravenheat-problems.65241/

http://npht.forumotion.net/t5-ravenheat-sequence-of-operation

https://www.justanswer.com/uk-plumbing/783mi-ignition-problem-ravenheat-csi-primary-condensing.html

acp
August 2017