Combi boiler problem?
My combi boiler is currently set to heat water both for the radiators & the taps. It's on a timer for the heating and it kicks in fine but has a tendency to cut out prematurturly. When this happens it sounds like water is still moving through the radiators. There is a noise which is present but isn't there when the boiler is heating water. Resetting the boiler makes it kick back in again. Similarly with hot water sometimes the boiler won't make any until reset. Other times it will start hot then run cold and need to be reset. If I switch the boiler to heating water only for the taps I still get the same issue. At no point does the flame failure light come on.
Perhaps there is a quick fix for this I can perform. If not I have a service plan, but I would still like an idea of what's wrong before I call an engineer out.
Update:Boiler is a potterton performa 24 I can't currently provide a cold water pressure reading but with the heating on as it is now the water pressure is 1.8 bar. The unit has 3 lights one for power which is on, one to indicate if the burners are lit or not. And a light labelled flame failure which I haven't seen illuminate during the cause of this issue.
Comments
Make and model of the combi would help..... any flashing error lights or codes?
Unlikely a primary sensor fault as most modern combis operate on the basis of a set resistance range of the sensor - if it goes out of range the circuit board issues a fault.
Also, if it WAS overheating, it would do so MORE on hot water than heating,
Make and model, once again please
edit - hard to diagnose without seeing it on site as this boiler lacks the 'failure' led of some of its fellow models. This is basically a baxi 105e boiler without the nice facia. It could be a pump proving diaphragm fault, air pressure etc etc,
I suggest you get someone in to have a look at it, as its pure speculation by any of us with the symptoms you describe. Yes we could have an educated guess but thats no help really.
I could throw all sorts of big words like 'primary sensor' 'hot water thermistor' etc etc at you but without testing the component and seeing the fault its all guesswork. This model as I say doesn't provide a 'fail point' led as some do to indicate if its an air flow/water/sensor/flame fault.
My suggestion again is to get somebody to have a look at it, and never DIY on gas
Check the water pressure gauge and make sure it is at least set to one and a half bar when the boiler is cold. if it is nar zero, then open the filler valve underneath the boiler and let more water into the system. Turn it off when the gauge shows the required pressure. You must set this with the boiler cold, as hot water expands as it is heated and you can have a false water setting if you do this when it is hot.
Probably one of the temperature sensors is faulty. Most likely in the primary side.
The boiler is overheating which is why it needs to be reset and would explain the erratic temperatures.
Its heats hot water then overheats and cuts out which is why it goes cold and then has to be reset.
Same with the heating it starts up and then overheats and stops working til you reset it.
If you have one of those big red ball shaped tanks in your setup, then check to see if the pressure gauge on it is about 1.5
if it is less then there is a valve attached to it to let in a bit more water. Turn it so the pressure is then reading approx 1.5.
If you have a service plan then it is best left to the experts. You may have problems with the pump OR water pressure.