Baxi 80e combi fault

[avant]

i have a baxi 80e combi boiler ,fitted about 18 months ago,my problem is on dhw side the burner ignites and the leds (water temp)go up as normal but then the burner cuts in and out giving me lukewarm water.Its as though the burner is tripping on high temp although the thermostat doesnt seem to make much difference.Central heating is not affected at all.I also had a combi mate scale inhibitor fitted at the same time. Any info will be a great help as i would like some ideas before i call a plumber. thanks for any help

 

[DP]

was the system chemically cleansed? Drain down does not count.

 

[Baxi-Remeha]

sounds like the board could be knackered, or the micro switches could be faulty.

 

[ChrisR]

Cutting in and out how often? What is the h water flow at the tap in litres per minute?
Could be the HW temp sensor, as well as the above, I think.