Sine boiler problem

[MrHarrison]

Hello, I hope someone can help me

We have a Sime combi boiler, Planet Super 4 wm model

The hot water is fine, but since putting the heating on again, the boiler fires up, then approx. 10 seconds later the burner goes out, pump still runs.

The flow seems luke warm but return pipe under the boiler very hot

We have 1.5 bar pressure

I have checked the 2 pumps and they seem ok

There is a low water transucer and that has no continuity across the 2 pins, could this be the cause?

Thanks for any help available

 

[Agile]

Is that the storage floor standing model?

They are pretty rare but by chance I fixed one of them a couple of weeks ago.

It may be sludged up to cause restricted rad flow? Or TRV pins are jammed down?

The pressure sensor is a transducer and gives a variable output depending on the pressure. Apparently they had a reliability problem with them from about 2004 and the information seems a little difficult to understand. I doubt its that in your case!

Tony Glazier

 

[MrHarrison]

all rads seem ok, pins and all valves open

sludged up where do you mean? in the pipework somewhere?

Thanks for your help

It is a wall hung boiler but has stroage

 

[MrHarrison]

just seen the transducer resistances in the manual! Thanks for helping Agile

 

[picasso]

More likely a stuck nrv on the ch circuit, try lightly tapping the nrv housing, its just above the ch pump while the ch is running.

 

[MrHarrison]

thanks I'll try it now, didn't realise it has a nrv inside the boiler! Hope it frees

 

[MrHarrison]

i tried tapping it but no joy yet, am I doing it wrong so to speak?

 

[picasso]

difficult to tell from a computer screen, how did you check the pumps were ok ?

 

[MrHarrison]

listened with screwdriver, removed vent plug and turned anticlockwise, not stiff at all, tested resistance of them both. Don't sound noisy at all, just normal.

 

[MrHarrison]

could air be trapped inside the boiler?