My first problem is that I cannot I.D the boiler. There are several model numbers on the User Guide but no markings on the boiler itself to identify my particular model. It is one of the following :

RSF 84ET, RSF 84E, RSF 100ET, RSF100E WITH OR WITHOUT BUILT IN TIMER
Are there any identifying features / markings to look for to narrow it down to my particular model ?

Secondly, the reason behind my need to I.D..we have lost hot water.
I can still get warm water if I switch to the Heating / Water setting but on the hot water setting alone - cold.
Any advice on resolving either problem would be very much appreciated.
thanks

alan, June 2009

It definetly sounds like a faulty divertor valve. However before you noticed this problem was the HW ok. The diverter valve has a tendency to seize up if the secondary heat exchanger has been blocked.
You can only see the data badge for this boiler from viewing the boiler from the underside (by the pipework) it is located on the right hand side panel closest to the back wall.

j, June 2009

This table can be useful

http://www.homeheatingguide.co.uk/efficiency-tables.php

It's a Ravenheat boiler - if it has a built in timer it's probably an RSF 84ET or an RSF 100ET

If it doesn't have a built in timer then probably RSF 84E or RSF 100E

The difference between the 84 and the 100 is the heat output - 84 = 24.1 kW and 100 = 29kW

The efficiency according to the table is about 77% which is quite low. "High Efficiency" is probably just marketing hype. 90% efficiency and more is not uncommon in modern boilers.

I am not a boiler person and put lots of rubbish answers in here but I would guess the diverter valve is playing up - you probably need a service engineer. They are all excellent and none of them ever guess what the problem is - like I do.

http://www.diyfaq.org.uk/plumbing/combi.html

Good luck...

Peccavi, June 2009