Biasi Riva Compact 90E-24S - Only ignites sometimes

[hurders]

I've got a Biasi 24S, probably about 8 years old which isn't igniting properly. Seems to go through all the right motions when powered on - pump starts, fan on (I think, need to double check), and then it tries to ignite (you can hear something clicking away for a few seconds) but no ignition. Odd thing is that sometimes a few seconds after failing to ignite the green light will start flashing quickly (indicating a fault), other times it just carries on blinking slowly (as per normal operation) whilst the pump keeps going but obviously no ignition.

As said, there are odd occasions (after powering it on/off at mains a few times) when it will fire up (maybe 1 in 5 tries) and when it does fire it'll operate correctly for c.h and d.h.w until it turns the flame off (e.g. when it reaches the temperature as set on the c.h. control). Once the flame is out (pump still running) it again refuses to re-ignite on demand (running hot tap or setting temperature control to max doesn't ignite it but you can hear it trying (clicking) for a few seconds).

I've seen quite a few threads regarding ignition problems on the Biasi Riva Compacts and it seems that the primary flow switch, ignition P.C.B. and air pressure switch are common sources of the faults? The fact that it does on rare occasions decide to fire up gets me thinking that it's a dodgy connection with something somewhere rather than a full-on failure of one of the components?

 

[Agile]

It can be caused by many things and some are gas related which we dont give advice to DIYers about.

If the flow switch is activated as yours seems to be then its most likely to be a failing ignition PCB.

But as these are expensive it may be better to get a boiler engineer to check as it might be something minor instead.

Tony

 

[hurders]

Thanks, likely I'll be getting an engineer in, just wondering if there were any checks I could do to give me some clues as to the cause of the problem?

 

[Agile]

Not that you can do because it means checking gas aspects first to eliminate them.

Tony

 

[hurders]

Ok the boiler now seems to be firing up as it should (although can be a little slow sometimes taking almost 30secs from turning on to flame) but I have another issue now in that when the c.h. is on and running, if I turn on a hot tap the boiler will click (sounds as if it recognises the request for d.h.w) but then extinguish the flame!?!

If I set the boiler to just d.h.w (summer setting on the dial) then if I turn on a hot tap the boiler does click in and ingintes on request and tap water gets hot (but sometimes takes a while from request to ignition - maybe getting on for 20 - 30s, other times it's fairly instant - less than 10s).

So seems c.h. and d.h.w do work and ignite the boiler when operated seperately but when used together the d.h.w request extinguishes the flame?

 

[Agile]

I cannot come to any further conclusions from that information. Its possible that you may have two faults.

You dont mention anything about ever having the boiler serviced but if that was done properly then any of those issues would have been highlighted and could have been attended to.

The boiler should ignite on DHW within about five seconds so that delay can indicate a problem. That could well be a slow to respond pump pressure switch. You could watch that and see how it moves.

Your boiler is an M90E. The 24S was an earlier model and will confuse people if you call it just that.

Tony Glazier