Biasi 24S boiler - no DHW or CH - please help!

[BENRIBBANS]

Hi,

My Biasi 24S has a fault. When asking for hot water or central heating the boiler will ignite and flame for a few seconds then switch off. This process then repeats continuously on both DHW and CH.

It was working ok up until a few weeks back when it did as above but stayed on for a minute or so then switched off, on then off etc. This was enough for having a shower, washing up etc but now we have nothing. Please help....

Any thoughts on what it could be and would it be a DIY job?

Thanks for your help

Ben

 

[BOB.DOLE]

flame sensor. BOB

 

[Rob]

or possibly air flow/aps problem

 

[BOB.DOLE]

or possibly air flow/aps problem

IF IT WHERE THE APS it would not spark and ignite.

 

[Rob]

how do you know its not dropping out after ignition. problems with fan venturis usualy give similar symptoms. although it is more likely your diagnosis.

 

[BOB.DOLE]

how do you know its not dropping out after ignition. problems with fan venturis usualy give similar symptoms. although it is more likely your diagnosis.

could be but i always go for the easy ones first

 

[Gasguru]

Check the little cap is in place on sense outlet (top of boiler, right hand side near the front edge). Sometimes they work for years with the cap missing and then start playing up.

 

[ACOperson]

Where's Agile?

Probably fixing one of these as we speak...

 

[BENRIBBANS]

Hi,

Thanks for the replies. After a quick scan of the service manual it identified some areas to look at for possible causes. Most were gas related so I left well alone but one mentioned the main system flow switch (microswitch).

I did a quick test (as the book instructed) and the diaphram seemed fine, the little needle moving in and out. Also with the hot water tap running I held down the microswitch with a small screwdriver and this allowed the system to fire up and stay on. I then reassembled it and it is now working. I also refitted the cap on the sensor outlet as suggested - thanks.

So the systems works for DHW and CH, the only thing is if you turn the tap on full the water cycles from hot to cold, but with the tap around half open the water is a constant temperature which is perfect, temperature setting about half way on the main panel. This would suggest to me that the heat exchangher is not working particularly well as it is unable to heat the water fast enough at full flow..??

Any ideas? I have signed up with BG for a service contract (£12 a month) so hopefully it will last out until that kicks in.

Also the pressure/temp gauge on the control panel is faulty. The temperature needle just reads zero all the time - is this an easy repair?

Thanks for your help so far

Ben

 

[Agile]

The 24S is pretty basic compared with the latest Biasi M110 premix Band A boiler which is much more fun.

I have been fixing a very elderly Potty Lynx this evening. Thats mostly only because the owner is even more elderly at 83 y.o. I did rather like the next door neighbour who it turns out has a key for the 83 y.o. I may go back there to check the old Lynx next week.

The problem this person has with the 24S is caused by the fan/venturi but because that should be dealt with by a CORGI I cannot give detailed instructions.

The hot water cycling from hot to cold every 15 secs is caused by the usual blocked plate HE. The standard BG contract does not cover that!

The temperature sensor phial may have come off the flow pipe on the left. Otherwise the whole gauge needs to be changed involving draining down. Since the temperature indication is only of use to an engineer I see little point in replacing it.

Tony Glazier

 

[duncs sweede]

Hi

I have exactly the same problem. My boiler is brand new and have had a new plumbing system put in, i.e new piping system. The boiler has been working fine for a week and all of a sudden..nothing! The flame goes on for about 4 seconds then cuts out, no central heating or hot water!! Any Ideas?

 

[Agile]

We would have more ideas if you stated what make and model your boiler is!

This discussion is about a Biasi 24S which was produced between 1997 and 2002.

All boilers installed now have to be condensing and if yours was also a Biasi it should be an M96 hybrid or an M110 premix.

Unless yours is also a Biasi and you give details of the installer who is responsible for a proper job then it might be better is you started your own new discussion.

Tony