gloworm compact 80e dhw luke warm

hi ,i have luke warm dhw.central heating is fine and the turning temperature control knob makes no difference.it gets hotter if you reduce the flow to the tap.i have checked the resistance to the thermistors ,the manual quotes 10k ohms at 25c ,i am getting 3.9 on both ch and dhw.i dont think its these as there both the same readings and the ch is fine .any ideas please

diverter valve or sludge in the dhw heat ex is normal

hi i have now changed the diverter and its the same .Is that the plate to plate exchanger for dhw. thanks

Three things on Compact 80E

Most Likely 1) Diaphragm on DHW split and/or pin stuck (its the right hand bronze looking thing held on with star screws, and with a black micro switch clipped on.
2nd most likely2) Plate to plate heat exchanger blocked/crudded up.
3rd most likely 3) Adjustable thermistor on back of PCB not turned fully up
there is a little black tool like a stylus clipped on the back of the fold down control panel..you need to look on the manual to see which is the DHW thermistor.
4th Most Likely is diverter in hydro block not being switched by Stepper motor on LHS of hydro block

For 3 you need a Corgi as you have to measure the Burner Pressure as you adjust it to make sure BP is to spec.

I deal with these all the time, though none this weekend funnily enough.

Alfredo (Now someone help me with a damn Potterton Puma..PLEASE!)