Suprima 30 overheating ?

[bernardgreen]

My daughter has a Suprima 30 in the house she has just bought

Untitled

• bernardgreen
• 8 Dec 2009
• 1

which runs for between 5 to 30 minutes before locking out with the red LED flashing. It almost always requires a manual reset each time.

The temperature of the out flow is very hot whether the temperature control on the boiler is set to high or to low. ( I had no thermometer to measure the water temperature but there was no discernable difference between the extremes of temperature control setting )

I suspect the temperature control in the boiler has failed and the over temperature safety cut out is operating to shut the boiler down.

If the temperature control is working then does the Suprima 30 burner modulate by turning off and on or is the flame height reduced when the out flow is at the required temperature ?

Knowing the quality of the PCBs in some boilers I suspect a PCB failure but would prefer to check the thermistor is giving the correct resistance before paying for a new PCB. Where can I find the expected resistance values of the thermistor at various temperatures ?

 

[kevplumb]

My daughter has a Suprima 30 in the house she has just bought

Knowing the quality of the PCBs in some boilers

some boilers suprimas are or should be known as the worst offender for duff pcbs

 

[gassafeman]

system diagnosis may help.

Paul.

 

[kevindgas]

turn power off
remove screw in middle of control and slide forward to remove
check how its wired!
should have
L
N
E
SWL

then pump
L (as a minimum)
N (may be empty)
E (may be empty)
if the pump isn't wired at all then the pump overrun cannot work.

switch on and check the voltage on the pump L should be 240v it should remain 240v until the boiler cools to about 60 degrees after it has been on

switch off replace cover and switch back on

this will verify if the pump over run is faulty.

most likely it will be the pcb, if it is ring poxibatterton for a fixed price repair as it will be cheaper than getting a RGI

 

[bernardgreen]

Pump is wired to the boiler's pump live, ( neutral and earth have been commoned ) so if boiler wants over run it will get it.

The fault appears to be loss of temperature control in the boiler requiring the safety overheat sensor to operate.

Having read another thread on Suprima PCB faults ( dry joints and broken tracks ) I am coming round to the idea of a new PCB as the quickest route repair. But for how long will the new PCB last if the build quality has not improved.

 

[Diyisfun]

Pump is wired to the boiler's pump live, ( neutral and earth have been commoned ) so if boiler wants over run it will get it.

.

But does the pump run?

 

[bernardgreen]

But does the pump run?

Pump runs, all radiators heat up.

Having spoken to the technical people I am now aware that the thermistor in the boiler has not been fitted properly and may even be the wrong type and hence the temperature control cannot operate correctly.

Instead of fast-on connectors the leads from the PCB have been soldered directly to the wires of the thermistor and heat shrink sleeved. Looks like a bodged repair.

 

[SpudMurphy]

Hi Kev, I changed one these PCB's today (what a beast of a thing) Everything fired up ok, got a phone call off the customer saying that the boiler wont turn off even when programmer and room stats are off. Would you know what that could be?
I followed the info stage by stage

 

[Boilerman2]

L & SwL reversed?? double check U'r wiring!

 

[SpudMurphy]

will do, but was sure I wired like for like as old PCB
Is there a way to test Live and Switch Live?

 

[45yearsagasman]

If programmer is all off there should be no power to switched live terminal and 240v to the permanent live terminal.Use a meter.If you still get 240 on the switched live then either the wiring is wrong or there is a system control keeping the boiler on.(dodgy motorised valve for example)