suprima pcb or 3 port valve

[WebMasterZ]

I have a suprima 50 l about 3 yrs old that seems to have the lockout curse suffered by many others.

I have cleaned out the boiler, it has had a new pump today, and about 4 months ago a new 3-port valve.

I have just noticed the rad in the hall the only one without a trv is stinking hot !!!!
The ch is off on the programmer & the hw light is the only one alight on the 3-port valve.

Is it the valve or the programmer or what?

TIA

 

[ChrisR]

Valve's stuck mate.

 

[gazthepottertonengineer]

definately not pcb for a change

 

[WebMasterZ]

Thx guys,

Free'd the valve up, radiators not hot anymore.

But the boiler locked out

 

[gazthepottertonengineer]

Doh perhaps it is the pcb as well then if boiler is under 5 years old i would call potterton to change pcb as they will charge £170 including parts and if you call anyone else it will cost them more than that for the pcb kit

 

[WebMasterZ]

ok story so far

boiler has locked out a couple of times since yesterday!
each time seems to be linked to a sticky 3 port valve (new myson 322 head about 4 months ago)

If its the internals of the valve are there any serviceable items inside?
I know if you remove the mounting plate water comes out (dont ask) - guess thats why it has "do not remove" stamped on it .

The pump is mounted vertically 6" above the valve with a gate valve.
Then two horizontal pipes one straight into the immersion tank and one dropping to the ground floor.

If I shut off the flow above on the pump can I replace without draining the system.


"How longs a bit of string?"

 

[kevplumb]

If I shut off the flow above on the pump can I replace without draining the system.

no it will flow back through the return



info on valves etc here

 

[WebMasterZ]

Thx Kev

So I need to turn off the mains, and the gate valve on the ch tank supply in the loft
and drain from the ground floor radiator?

cheers m8

 

[WebMasterZ]

Update

I have now replaced the pump and the three port valve (valve was broken inside & pump was noisy)

On occasion the boiler still locks out but allways relights immediately, sometimes (not always) when it locks out the pump continues running!

A friend of a friend (corgi reg) assures me its the thermostat in the pipe at the boiler and not the pcb at fault.

Do I replace both the temp thermistor & overheat thermostat ?

Its cheaper than a pcb but not if I end up changing the pcb later.

PS all fault finding from the manual is correct, but then it's an intermittent fault

TIA

Tpny

 

[Agile]

Have you considered that it may have reached the set temperature and cycled off? Did you measure the flow temperature with your digital contact thermometer?

If it "locks out" then one would expect it to remain "locked out" because thats what locked out means.

Bit like the "Do not remove" which you seem to have removed. At least that made me laugh for a change.

Tony