hi i have a Main Combi 24hp and was loosing presure.i refil with 2.5 bar and now it start just for 5 second after is stop after 10 secon is start again for 5 second and after the red light is comming...can you help me please

You should top it up to 1-1.5Bar only when the system is cold mate. Do that & come back to us.
Your problems may be caused by a few things.

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thank you very much for replay ....i refil with 1-1.5 bar but the problem is still remaining....the burner stops after 5-6 second every time...

a common problem with those boilers is the APS, you'll need a gassafe reg plumber to fix that problem, probley cost about £70 if he's a decent chap

Do not think the problem here is the aps,probably problem with flame recognition,best get a gas engineer in

Be safe and prosper

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