Odd little problem on a Biasi - any ideas please?

[Masood]

Morning all,

Went to do a LSC last night, there's a Biasi Parva M90.24. Everything works just fine, heating, hot water, no issues.

Except - the tenants say that every now and again, the boiler will fire in short bursts, a few times, then settle down again. He reckons it fires 4 or 5 times for about a second each time. There is no pattern to this, happens at irregular intervals, no specific time of day. There are no external controls. The only thing out of the ordinary was that the clock had not been set on the boiler. The landlady had apparently said that it was not working, this wasn't the case, I set the clock and programmed it for the times they wanted. I'm wondering if the clock not being set could have anything to do with it? Clutching at straws, I know!

Any input gratefully received, as ever.
Masood

 

[Blake]

Does it have a pre-heat for the hot water?

 

[Masood]

Does it have a pre-heat for the hot water?

I did think of that but no mention of it in the manual. Just downloaded the user manual and there's mention of an in-built frost stat. Wonder if that's on the blink..

 

[woodsy]

Had a similar problem and it was when somebody opened a cold tap which turned out to be the infamous deadleg

 

[Masood]

Had a similar problem and it was when somebody opened a cold tap which turned out to be the infamous deadleg

This ia happening all on its own - sometimes in the middle of the night, so not related to taps.

Speaking to Biasi, they say the inbuilt frost protection works off the NTCs, and they apparently are prone to failing, tricking the boiler into thinking it's below -4...

 

[Billy Bob Bob]

take the black motor off the dv see if its wet

 

[Masood]

take the black motor off the dv see if its wet

Dry as a bone! Are you thinking that it's weeping, causing the boiler to think there's a DHW demand?