its an apollo 30/50
the boiler egnites up giving heat and hot water for 5 minuets.
when it reaches the desired tempeture the pilot light doesnt stay light and the boiler shuts down completley and all of the components seem in good workin condition.
what is wrong with it?

plumber, October 2010

By your description, the boiler is overheating, there is an overheat stat that interrupts the thermocouple should overheat occur.
Initial 4 possibilties:
Pump sticking.
System by-pass closed.
Faulty pump overrun thermostat.
Faulty High or Low boiler thermostats.

Carefree, October 2010