britony 80 combi no DHW/CH

[abs]

can anyone help
i have a britony 80 1998 model was working fine until a few days ago.
it refuses to fire up when the hot water tap is turned on or the central heating
when the boiler is switched on the fan runs constant even with the hot water tap turned off , when the tap is turned on the pump starts working but there is no ignition and also the gas solenoids do not open. i have checked the following

Both flow valves were removed checked for ease of opertion and refitted.
Checked air pressure switch for continuity as per download for boiler.
Checked all fuses in pcb boards
Checked for dry joints on pcb

and still no joy, i don't understand why the fan runs all the time but if you pull off the wires to the dhw flow stat the fan stops?

 

[Agile]

It sounds as if the system flow switch is jammed on.

To progress further you would need to do useful electrical tests!

Boilers are not usually mended easily and your model is avoided by many boiler engineers.

Tony

 

[abs]

there is continuity between both terminals on the flow switch at all times but not checked for voltage yet. i have removed the flow switch which seems to have a brass rod with a magnet stuck on top. cleaned the rod up and checked for smooth operation seemed fine. done the same for the ch flow switch.
the only other thing is that the boiler was running with no water pressure before it packed up. but i do not get no lock out led come on.

 

[Gasguru]

With the boiler off there should not be continuity on either the hot water or the pump flowswitch reed switches. A common fault on these boilers is for the reeds to short out. The replacement flowswitches are of different design.

 

[Agile]

Running dry with a failed system flow switch could have caused some damage!!!

I am surprised you did not realise the flow switch should not be constantly made. Testing it electrically while manipulating the magnet is part of testing its OK if you take it out !

Tony

 

[abs]

just doing all checking myself have a back ground in mechanics its just i had a engineer out to it and he just took one look and just said it needs replacing without doing any checks. i,m having someone else coming out to it today so fingers crossed

 

[abs]

had a engineer out to the combi today, the flow switch was faulty and was replaced. but the combi still does not ignite he suggested a new pcb to be fitted.

 

[Agile]

There are several things to be confirmed before changing a PCB !

Does he have the confidence to promise that he will not charge you for a new PCB if it does not cure the fault?

They are a bit fiddly to change!

Tony

 

[abs]

the engineer is a family friend so did't charge to check it out for me
as the fan was on constant he first changed the flow switch and that cured that problem.
We have checked the operation of the air pressure switch and the feed to it it works fine.
Checked the flue for blockage all fine
Checked the over heat stat switch all fine

so he's pointed to the board. i have removed the power board and control boards checked for dry joints and also checked the on board relays which all work fine. but there is nothing else left to check i,m told apart from replacing the board.

if anyone has any more suggestios which can help please advise

 

[Agile]

I dont see any mention of checking the sensors hot and cold ???

 

[abs]

I dont see any mention of checking the sensors hot and cold ???

i replaced the thermistors today.but still the same the engineer is saying that there is nothing left to check and its the board? but cannot say which one.

 

[Agile]

Well I would agree it must be the PCB if I felt confident that everything had been properly checked!

However following the difficulties you had checking the flow switches I hope you are lucky!

One of the PCBs is primarily a power supply and the other primarily a control PCB. I would suggest you should change the control first but either could be at fault or in the extreme case BOTH !

A PCB failure on most boilers is very rare! ( Yes excl. Potties ! )

Tony

 

[abs]

i have been studying the in's and out of one for the last 3 days getting to know how one works, just one more question whats the job of a ionization electrode? does that stop the ignition when the burner has fired up?

 

[Gasguru]

The ionization electode detects the presence of the flame. The board needs to know that ignition has been successful. Repeated failures to ignite results in lockout.

 

[abs]

The ionization electode detects the presence of the flame. The board needs to know that ignition has been successful. Repeated failures to ignite results in lockout.

will i be right in saying that if the electrode was faulty and detecting a flame that will stop the ignition process