Have posted this problem in plumbing section 3 times now with no reply,so can only assume was in the wrong section or my question is really stupid ,please help.
I have a Heatline C28 combi boiler which works perfect for the central heating,but having a problem with the hot water .when the hot taps are open water will start off cold,which I understand ,will eventually become quite hot and then will fluctuate between fairly hot and tepid ,absolute nightmare trying to fill a bath because just with the hot tap on the bath can at best be described as warm.
As I said this happens with every hot tap in the house ,the shower works ok though ,the temperature remains constant.
Would really appreciate any help,thanks
The fact that your shower is working properly suggests that the boiler is ok.
Filling a bath from a combi boiler will always be a slow process, because a combi can only heat a relatively small amout of water at any time. If you fully open a bath tap I would expect it to run hot and cold as you have described. Similarly opening more than one tap at a time can easily overload a combi boiler.
Try reducing the water flow to a more gentle flow ( do not shut it down to a trickle or the boiler will go out ) and see if the temperature remains constant. If it does it suggests that you are simply demanding too much water too quickly.
I doubt this will be of any help to Jouls, unless the 4 plumbers you called out are totally incompetent.