I have a condensing boiler for central heating and mains fed domestic hot water. It is a RD 532i (made for British Gas by Bosch) and is only 4 years old.
The central heating is working fine, but over the last 7 days the hot water has on about 5 occasions not been hot. This evening for about 2 hours there was no hot water, whereas yesterday it worked perfectly. However, the day before that it didnt work for about 1.5 hours. A few times over the past week it has not worked for 5 to 10 minutes. During the periods when it doesnt work the display on the boiler shows the actual HW temp as around 19 degrees and then when the hot top is turned on, it rapidly drops to 9.5 degrees! Does anyone know what could be the problem here, and if so, who should i call to fix it and is it going to be expensive. thanks