Myson Midas boiler

[sparkynotplumber]

Can anybody shed some light on a fault. The boiler all of a sudden cut out, called a local firm who said it was over the hill (approx 15 yrs old) boiler sound but something to do with electrics, control boards etc. The company I feel just wanted to sell me a new one. With being an electrician decided to have a look myself and found a relay burnt out on the control board to the right (as you look at it). Replaced that today but all that happens is as soon as the pilot light is lit the hot water system kicks in even though there is no hot water tap turned on, it overheats an cuts out again. Help! don't want to fork out £2000 for a new boiler just before Christmas

 

[pannierstan]

Fantastic boilers these!

True fault finders dream.....or is that nightmare!

What model do you have exactly as there is a bit of mist tonight and I cannot quiet see from here

Stan

 

[sparkynotplumber]

The rating plate says Midas BF, if that is any help

 

[sparkynotplumber]

Hi stan
Also since I fitted new relay the heating now works if I discontect a plug from a device which is fitted from the cold water pipe (may be a pressure switch/flowswitch/thermostst) it is situated to the lower left of the hot water pump and has a two wire feed to it. I have removed both control boards and have checked them both and seem to be OK. If I keep the hot water tap on after I reignite boiler it works fine, I think the boiler controls think there is a hot water tap on and fires up when there is not. Is this device the problem? is there a pressure/flow switch on this model. Its now doing my head in.

 

[pannierstan]

Well I think you are talking about the DHW flow switch and yes disconnecting that would prove that it is indeed stuck.
Will the heating work if this switch is disconnected.

Stan

 

[sparkynotplumber]

Hi Stan, yes central heating works fine when this is disconnected

 

[pannierstan]

Well you need a new DHW flow switch by the sounds

Stan

 

[sparkynotplumber]

Hi Stan, thanks for all the help the flow valve is knackered have removed it, cleaned it etc but will not switch, it is the same readings if water on or off, I am limping by at the minute connecting and disconnecting it to get heating / hot water running. Next problem is finding a replacement. I have tracked a couple of sources but are wanting silly money £100+vat (for a switch!) is there a universal type you can fit or has it to be a Myson one.

Thanks again

Sparkynotplumber