hi all im new on here so hope this is in right place about 4 months back i had a part replaced on the boiler as it was leaking it was the diverter valve the boiler worked fine for a day or so then it started playing up the hot water comes on first time in the morning ok but if you switch it off and then try to get hot water again in few mins no way will it start again you have to leave it off for about 15 min to get hot water on again or some times it will work if you put the heating on with it but not always the boiler is valiant turbomax any help would be great thanks