Girlfriend called me up earlier, turns on the hot tap, boiler fires up but no hot water is supplied, just runs cold. So it seems to me the pressure sensor is working? What else could it be? Not sure of the Manufacturer, begins with M i believe, gonna pop over there later and take a look. Any suggestions appreciated.
thanks,
L
How long does the boiler fire up for ? Is it only staying for a couple of seconds or is it staying lit the whole time water is being demanded ?
There's firing up and there's firing up. Many people will say the boiler is firing up when all they mean is the fan starts. So check if you have a flame, if you have then the problem must be a stuck diverter valve (and the radsa will get hot eventually). If there is no flame then dived and conquer is the way. Air pressure switch? Ignition? Gas Valve? PCB?
(Don't jump to the last two untill you are 110% sure it's not the first two).
Thanks for your reply,
I've found out it's a Myson Midas wall mount combi
The boiler is 'working' as the rads are hot, the boiler seems to whirr up into action as soon as the hot water switch is turned on, and it continues to whirr until switched off again, but not change or click when the hot water tap is turned on, and no hot water. Off to investigate now anyway. Going to try and locate this divertor valve and pressure switch first then...wherever they are.
I'd say that your diaphragm in the diverter valve has gone, check this by manually lifting with a screwdriver the micro switch which it controls (with a hot water tap on) - new diaphragms cost around 10-20 quid.
Jon
In message , John Smith writes
** The Myson Midas has two separate pumped systems, one for hot water, one for central heating. I don't think there is a diverter valve (it's been a while since I tested any midas boards) ** The Midas also doesn't have an air pressure switch, it has an air flow sensor which is basically two NTCs, one in the air flow, one not.I would check that the pump impeller hasn't broken off the shaft first. Then check out the hot water flow sensor.
Do you have a manual for the boiler, you'll need one. There are a series of LEDs on the main pcb which indicates what the boiler is trying to do.
There are two versions of this boiler, one has a 404C147 main pcb (usually blue), the other has a 404C656. They work slightly differently to each other
Be warned, his is a complicated boiler, you might have let yourself in for a little more than you first thought.
No, it doesn't have one
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