Halstead Ace DHW only just warm

[nitram76]

I've got a Halstead Ace which has started producing only warm water instead of the scalding hot it used to.

The CH works fine and the DHW is hotter when the CH has been on. The CH flow pipe is also red hot when I switch the tap on. Is this the diverter valve as I suspect and if so, how much would a new one be and how much of a job is it to do?

I'm a maint. technician by the way not a dafty and if I can't do it I'll pay someone else.... just trying to save a few quid if I can!!

 

[MANDATE]

If you've had the front off, you'll see a micro switch secured to the left side of the diverter valve, but on the right side there is a ' housing unit' and within that unit is a rubber 'diaphragm'. These diaphragms seem to be a common problem.
I've just dealt with a similar problem, basically no DHW although when heating was on the first pint of water was warm.
There are repair kits for the diverter valve and for the 'switch housing unit'
The 'switch housing unit' one is just over £30, but I found I could get a 'diaphragm' only of different make for £4. Which was for a Vokera code 0870. So far it's been in about three weeks
Instructions suggest removing the two sensing pipes from 'housing unit' end which I found to be difficult, so opted to remove from other end.
This was quite easy as long as you allow 'housing unit to move to the right after releasing the two securing screws.
There is no need to drain the heating side, just stop the cold mains water going in the boiler and open hot tap. When pipes removed expect no more than a tablespoonful of water.
In my case the installer had placed the isolation valve on the HW outlet pipe instead of the inlet, so I had to use the house stop cock.

 

[MANDATE]

Instructions also state/imply after lowering the control panel that it should be removed, but that would mean removing pressure gauge and draining system. This is not necessary, agree panel is a bit in the way but not a problem

 

[Pase1]

Thanks Mandate, done as you suggested.
Not happy with screw heads when allen screw or bolts would have been more sensible but then they have made the threads non standard disabling a sensible replacement. Needed grips to slacken off the screw at the left hand side. A bit like the right hand pipes hard to get to. Apart from the stated daftness it`s an easy fix.
Thanks again all.