Biasi M96.28SM/D problem

barryvanhire · 27 Sep 2010

Hot water is working but central heating isn't coming on.

getting alternating green lights on front panel.
Have bled rads
turned wall mounted thermostat up full
bled pump
ensured pressure is at 1.0 bar

still no joy

Any suggestions or help would be most appreciated. I'm very much clueless about this sort of thing and have just followed the FAQ's on the forum so far.

transam · 27 Sep 2010

All of these varous Biasi model codes , does my head in

but 2 green lights (alternating) would be the sequence when the boiler is drawing hot water ? there fore if they are alternating when you are not making any demand (Tap off) it would or mighrt suggest that the Hot water flow switch is stuck , & the boier thinks a hot water demand is being made hence why it will not turn on for central heating ??

barryvanhire · 27 Sep 2010

thanks, that's interesting. I have a leaky hot water tap in the bathroom. do you think this is the root cause of the problem?

transam · 27 Sep 2010

Depends , it would have to be a substantial leaky tap & your boiler would be constantly on firing , If your boilre (?) hot water switch is stuck than the boiler would be firing intermitently , on a regular basis for very short periods ! there is a red neon light on the HW flow switch which would be on all the time if it is stuck ?

You would need to get some profesional help if it needs changing !

barryvanhire · 27 Sep 2010

I can see a red LED light on towards the back of the unit. I think this confirms your diagnosis.

Thanks for your help.

chrisgatguis · 1 Dec 2011

Hi, sorry to dredge this thread up from the depths of last year but I have the exact same syptoms as this,

What was the fix for you in the end?

Also did you do any tests with a magnet? If we unplug the sensor the flow LED goes off and C.h is able to work.

The problem I can't understand is that if a magnet is touvhed to the side of the sensor the flow turns on and when removed the flow stops (ie LED comes on when touched, and goes off when moved away)

Does this support the faulty switch theory or could it be the magnet mechanism or something else?

Fyi - I do have a boiler repair man involved in this but he can't get round for a few days (bringing a new flow switch) so I'm just pessimistically enquiring..

Thanks

Chris

Agile · 1 Dec 2011

chrisgatguis said:
Fyi - I do have a boiler repair man involved in this but he can't get round for a few days (bringing a new flow switch) so I'm just pessimistically enquiring..

Thanks

Chris

I think that you are going to need a better repairman!

Firstly one who comes the same day and secondly one who has an idea of how to repair boilers!

Tony

chrisgatguis · 1 Dec 2011

Thanks for your opinion on my repairman.

Any opinion on the problem?

Thanks

Chris

Dan Robinson · 1 Dec 2011

Jesus Tony, some of us are busy... Not everyone is quiet enough to do same day visits all the time.

Chris... do you have leaky taps or not? What happens when you shut the water supply off to the boiler?

Agile · 2 Dec 2011

If someone calls me before 1130 and has no HW or CH then I do my best to get to them the same day!

That can mean working late at busy times.

Tony

chrisgatguis · 2 Dec 2011

Hi Dan,

Thanks for the suggestions,

I don't have any leaky taps,

For some reason I can't get the valve to close fully and I'm putting a fair bit of effort into it (and the close direction is labelled).. So I decided to turn off the main supply to the house in the hope that this would simulate the same thing..

With the water off the feed LED is still lit up!

Do you think that supports the switch fault theory or something worse or just wait and see? :s

Thanks

Chris

Dan Robinson · 2 Dec 2011

I would say so... Switch should be fairly easy to change.

chrisgatguis · 9 Dec 2011

Hi,

thanks,

the boiler man replaced the little black DHW flow switch but the issue persisted unfortunately,

he then removed another large componant to the LHS of the switch to get access to the actual brass part containing the magnet..

this was the problem, it was stuck in place presumably down to limescale or something but he thinks the whole brass (large componant, dont know what it is) needs replacing and that the bit where the magnet / filter etc is not a seperate part... Hes going to find out from the parts place who apparently have diagrams etc.

Agile has given me some really good advice RE: getting the boiler serviced regularly on another thread so maybe something like this (limescale build up or similar) could have been avoided. I think I will have to look into this - first boiler I've owned..

Thanks
chris

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Biasi M96.28SM/D problem

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