Biasi M90E.28S Riva Compact Problem

[darkarius]

Having some issues with my boiler. It seems this is a recurring thing for these. The CH is working, but no DHW. As I've read on here and someone I know has also said, It seems diverter valves are quite the common culprit. Having gone to the biasi site and printed myself off a manual etc, Which actual part is it that becomes faulty? I'm seeing diaphram come up a lot in peoples posts, but by the exploded view I have it doesn't seem to actually have a diaphram on it. (unless I'm completely oblivious to it on the picture ). The things i can see which appear to be some sort of seal are whats listed as a 'central heating pressure switch disk' and a 'central heating pressure switch membrane'. Anyone able to throw some light on all this for me? Am I heading in the right direction, or way off? lol. Any help would be greatly appreciated. thanks.

 

[ChrisR]

Instead of the much mentioned diaphragm you have a dhw flow switch, and a motorised actuator to make the diverter operate. You should be able to find those in the manual - have you got the Servicing one? Check each is operating, electrically.

(dhw = domestic hot water = tap water rather than boiler water)

Do you mean that when you turn the HW tap on, nothing happens at all?

Tony lives inside a biasi so will be able to tell you what most frequently goes wrong.

 

[Agile]

Unfortunately this is one of the most reliable combis ever made so there is nothing that "frequently fails".

You can check the first requirement of DHW, that the flow switch operates by looking for a red light on the sensor towards the right hand side after removing the front.

If thats lighting then its just possible the NTC sensor has failed and that will make the green light flast double fast and can usually be identified by using the built in diagnostic facility. Replacing it needs some access on the right hand side of the unit.

Its also very important on this model that the boiler is set for the actual central heating demand and not left on max otherwise lime scale will be deposited on the primary heat exchanger.

Tony

 

[darkarius]

Thanks for your help fellas. Seems it was to do with the flow switch. I've had to pull the switch slightly forwards for the light to come on. For some reason it wont play ball when its sitting in what should be its proper position. No matter. I guess the clip maybe out of shape. Thanks again for your help. I can get back to having baths again.

 

[Agile]

NO wrong again!

Pulling the hall effect sensor forward WILL get it to operate but that will not ( normally ) be just when you use DHW although you can use it that way to get your bath but it will not provide CH if left like that.

If its not responding when in its fully seated position then either someone has reversed the flow and return pipes to the boiler or the magnetic shuttle is stuck.

Removing it requires the gas valve to be taken off first so it becomes a job for a CORGI engineer. Once removed it usually can be cleaned up and usually does not need replacement.

Tony Glazier

 

[darkarius]

Tony,
Going hypothetically that its the shuttle valve. Is that something an engineer would be able to do in situ or is it a case of things being removed. Either way, any ideas on what the costs would likely be for someone coming out to do it?
Thanks for the help.

 

[Agile]

It needs a competent CORGI registered person because the gas valve has to be removed to gain access. ( Unless the whole right hand hydraulic unit is removed instead, thats more work and wet ).

Doing it the gas valve way would take about an hour.

We would do it in London within our fixed price diagnostic fee of £84 inc.

Having said that its a bit demanding on the average person trying to fix boilers to even start to understand what the problem is!

You might be better to call Biasi on 01902 304400 and ask for their local service agent. But check first that they understand the problem and can quote you a fixed price to fix it.

Tony Glazier

 

[samaboy]

hi can anyone please help me with a problem i have with my m90e/28s ,i have just changed the motorised /acuater and when i put back on top of main valve and i put the little u shappe clip back in place i am haveing water comeing out of were the clip is ,is the main valve gone or is there any o rings to be replaced can you help please

 

[Agile]

Your motor had been damaged by a leaking diverter valve!

So you get a new motor and fit that without curing the basic leak which failed the original motor?

Is that a sensible thing to do?

Tony

 

[samaboy]

hi that is why i was asking if the main diverter valve has a o ring kit or does it have to be replaced ,idid not have manuel for this boiler . so if you could help it would be great thank you .