Appliance Repair Questions? Ask a Technician for Answers ASAP
Hi. Have you tried turning the power off for 30 secs then back on?
Also . is your heating system filled by a header tank or by the mains with a filling loop?
Yes the system has been up and down (on and off) many times during the last two days.
Header tank in the loft
Ok . so there is no power to the boiler? Can you check the boiler fuse is ok
Yes the fuse is OK
Sorry , you said it kicks in for a short time
Have you checked the pump is running , not just that it has power to it?
If I raise the temp on the hot water tank the system starts up (two green lights on the boiler) and the pump runs, I have put my hand on the pump housing and can feel it pumping
Ok . as you have no fault codes via the LEDs I would suspect the thermistor/ temp sensor. If its not this then you are looking at the PCB board. Change thermistor first as they are a lot cheaper than the boards
There is a code for PCB failure, could there be a fault and no code ? There is also a code for Flow thermistor and Casting thermistor faults, I am confused ?
'None of the led lights were lit . if the thermistor is faulty then the boiler won't run as thebboilercvmay think it is hot already. These can be tested with a mutimetervon ohms
Do nyou have a voltage tester or multimeter?
Ok . that's great . with the case off .and a call for heat ( programmer, room stat on)could you check for voltage to the fan
No voltage at fan
Ok .are any of the LEDs lit?
Ok .on theflow pipe ( top left) there is a flow switch and below it an overheat stat..are you getting continuity through these?
Yes continuity on both
Ok . there is a casing stat just to the left of the fan , could you see if you have continuity through this as well ,, thanks
yes continuity on that one
Ok . there is a flow thermistor somewhere. Can't see it on the diagram but its definitely there , should be on flow or return . coulkd you check bthe ohms reading vthrough it , thanks
Can not find it, any idea what area its in?
I can see it on the wiring diagram .I think it must be the flow sensor you tested earlier , top left on the flow , just need an ohms Reading for it . most thermistors operate between 2 thousand and 40 thousand and should change with a temp change
You might have to take off the wires to test it
OK sorry for the delay, a bit tricky standing on the ladder, 15K ohm
Sorry ,I know it can be a pain. I forgot to ask , did you check for voltage on switched live on the boiler wiring centre?
Ok . well that's good in one way as at least your boiler is probably ok . is that with the programmer calling for heat on hot water and heating?
Yeah, both calling for heat, as mentioned earlier its strange that if I just raise the temp setting on the tank stat it all kicks off ?
when it starts I get two green leds on the boiler panel, one for mains and one for burner on, but then it stops after a short while
Very strange. If you were to put a wire link between live and switched live the boiler should fire. Do you have a 3port/ mid position valve?
Yes to the three port mid positioned valve,not sure where you mean to put the loop feed?
On the boiler wiring connection link between live and switched should for and run the boiler temporarily if you needed it , but you would have to keep the boiler temp low otherwise the hot water would get too hot. But we need to find out what's wrong with the controls. It could be that the motorised valve is faulty and not pulling the motor over and operating the switched live.I think this is the most likely thing
I checked the MV this morning by rising and lowering the hot water tank stat thus making the mv swing between HW and CH,
It might be just short of making the switch . is it a Honeywell?
When the motors start to get weak they don't swing all the way across
The make is Drayton and the model # ***** *****
I fitted the MV in 2007, what is the normal "shelf life"
About 8 years. You could just change the motor, cheaper option but fiddly . pretty sure this is the issue
I think that is the way to go, lets call it a day, I will have a very close look at the MV tomorrow. Thank you for your help today.