Hi,
looks like I've made a bad purchase with a Ravenheat boiler CSI 85T ( 14 months old) . Boiler works ok in hot water to tap only mode but when in CH and hot water boiler fires up then shuts down after approx 20 seconds. It then starts back up after 15 sec and shuts back down again continuing in this cycle until turned off.
San
No you haven't made a bad purchase, a CSI85AT has a THREE year warranty. (as long as boiler is serviced yearly)
The problem you'll have if you do have the A band boiler is that the Fan modulation board will be faulty, very easy to replace.
Ravenheat offer a very good service with fair prices, if boiler is out of warranty