Hi, i hve a ravenheat rsf84et was working fine until last week whena ll of a sudden no hot water and no ch. ive reset the boiler and still nothing, the water pressure is fine. the best i can describe it as is when we run a hot tap we hear it trying to work but no clicking from the pilot light to try and fire up. is this a problem with the pcb?? please help!!! ps: sometimes we turn the tap and it works but only for about 10minutes and very rarely.