3 hours ago Sandy asked ... Replace vertical gear on Singer Fashion Mate 252?    |    Blaablaa asked ... How can I fix?    |    pete asked ... Flymo 330 turboglide?    |    keith asked ... Fuseboard( s) location of renault trafic t1100 1993?    |    Janet asked ... Neff B1641 door not closing at top?    |    Click here to ask your question

How do I fix my Worcester Heatslave 20/25 combi?

If I run the hot water for a few minutes the temp drops to about 20 degrees, I've turned up the dhw thermostat but this only makes the water hotter for those first few minutes. What else can I do?
Andy, October 2013
It's oil fired so I can't tell.

Andy, October 2013
can you see the burner flame going high then low then high again

A1, October 2013
link Click here to see other fixes for Worcester.