Biasi riva compact cutting out after 1 minute

[ItalianPaul]

Hi I have a Biasi M96 that was working fine but now only the hot water works ok. When the CH starts, it burns for about 1 min until the water reaches 30°C then cuts off the burner. The pump still runs and the temp drops to about 25° but it never re starts the burner.

If I run the hot tap the burner starts again, and then it switches over to the CH (with the burner still on) but only for a few seconds, then switches off the burner as above and never restarts.

There are no warning lights and it all seems OK other than it never switches on the burner again.

What is wrong??

THanks

 

[ChrisR]

Could be just a temperature sensor. BUt I can think of several other things... would have to be there

 

[Agile]

On CH what does it show on the lights at the point that the boiler stops firing?

Tony

 

[ItalianPaul]

Hi Tony - thanks

Its not showing any error lights - when in CH mode the I and III lights flash together as they should.

Surpirsingly my wife mentioned that its working OK today!!!! but yesterday it wouldnt light at all. Then after some coaxing it went back to the same as stated originally.

It must be some intermittant sensore fault? - but why not error lights?

 

[Agile]

The only way that it could create a situation like that is if the sensor is at a lower resistance but still within the expected values.

That would be a VERY unusual sensor fault though.

It really needs a measurement of the sensor resistance at the point that it turns off.

Tony

 

[Oooshk]

Same thing just happened to me....
The boiler lights up to supply HW, then goes out after 20 seconds...
also does a lot of cycling when the CH is in operation.
Unlike you however, mine is giving me an error code "CH Sensor fault".
So I got the guys in to have a look and they wanted (wait for it)..... £300 to fix it.
Went to keeptheheaton.com and bought a replacement sensor for 14.50 excluding VAT. Will drain and fit in the coming days!

I almost fell on the floor when they said 300 quid. 200 more and i'd be buying a new combi.