Turbomax HW - Luke Warm

[courage best]

My daughter recently bought a flat with an 8 yr old Turbomax combi. The HW wasn't too bad in the summer, but as soon as the incoming cold water got colder, it is only luke warm. To have a bath, you need to run the hot tap really slowly, even then the bath isn't exactly steaming.

A relative lives in the same area, which has hard water, has a Worcester junior of the same output (24kw), but the hot water that comes out the tap is almost boiling.

The Turbomax's hw control is turned to max. Is there a problem, or are these boilers normally bad at heating water? The heating is fine.

 

[gas4you]

There is a problem. This boiler should give 9/10 litres/ min hw at 35c temp rise, so this time of year around 48c out of tap.

 

[peter the plumber]

most likley the dhw heat exchnger.Is it the the turbo max with green buttons.These do block up and it will effect the hot water,its quite a easy job to do if you are pretty handy peter

 

[simond]

Check the gas meter handle is fully on before wading in with other solutions.

 

[courage best]

Thanks for your replies. The gas tap is fully on.

It's not the one with green knobs, its like the one on the right of the top three photos on here -
http://www.vaillantservice.co.uk/VAILLANT/Vaillant_TURBOMAX_Faults_and_problems_help.html

Yes, I'm going to DIY it. I trained as a plumber, back in the day, but didn't get too much involved with boilers. Only done plumbing for myself and family in last 30 yrs.

So, presumably the plate hex is scaled. What is best to clean it with? Is spirit of salts OK, or too agressive? What do I need to buy before removing the hex, possibly some new seals for re-installing?