Hot water has not been as warm as usual - this has been noticed over a
You need to work through the sequence of events. When you turn a tap on, does the burner light? I presume the pilot light is lit. Does this boiler run your CH too? I presume it does since you have a two way valve. If the CH is getting hot then the gas burner and gas valve etc must all work. Then you have to ask what happens differently when the hot water is demanded. There will be a flow sensor that senses water being drawn by a tap. If that doesn't work your boiler won't try and heat the tap water. There will be an overheat thermistor screwed into the hot water after it leaves the heat exchanger can, if that is wrongly sending an 'overheat' signal the boiler won't heat the water: its connections and resistance needs checking. There are a variety of problems it could be, including a duff control pcb. You need to eliminate the simpler ones first.
Are you intending to diagnose it yourself?
Andy.
I suspect that you have a system with a HW cylinder. Since the 2 way (3 port ) valve and pump have been changed (probably without need?) I suggest that the programmer/timer and the cylinder thermostat are up for testing.
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