Baxi Bermuda Inset 2 strange behaviour?

[bon98uk]

Hi All,

I have a Baxi Bermuda Inset 2 (Back boiler). I have just had the the Tempreature Sensor replaced and this has cured the problem I had with the boiler trying to start up but not lighting, going out quickly and trying to start up etc.

(Its a Gravity fed DHW/Pumped CH in 'C' plan configuration with a 2-port valve for the HW)

Now it generally works as expected except for one thing.

On occasion, the boiler appears to go through its start up sequence and the 'Green Neon' light comes on but the Main Burner doesn't fire up. So the boiler sits there with the green light on thinking its alight (the pilot fires up okay and stay on as it should do) but the main burners don't fire.

Once boiler goes off via the programmer and starts up in the morning it works okay but then may at some point go through same issue again.

Firstly the boiler interlocking is okay, I have checked and double checked all the control from the the Roomstat and the Cylstat. All 'wet' aspects are okay (pump works fine, MV works fine etc.)

The problem 'seems' to occur when the boiler shuts down when it reaches the control (or potentioneter set) temperature.

This Pot sets the output Wattage of the boiler and appears to work in conjunction with the Temperature Sensor. (I am guessing there is a simple OpAmp Comparator on the PCB that detects the voltage difference across the Sensor and compares it with that across the Pot. When equal a signal to 'shutdown' is sent until the Sensor 'cools' slightly. When working this 'cooling' delta is 6C on the Flow i.e. from 82C down to 76C before the boiler refires.)

The problem 'appears' to be an intermittent lockout but the lockout Neon doesn't light.

Has anyone seen this issue and can offer some insight?

My alternative is to do a parts overhaul but to me the Gas Valve seems okay as this only happens on occasion. Overhauling parts can be expensive so I want to narrow things down abit any ideas?

regards,

bon

 

[Slugbabydotcom]

I put that info through a great superhuman computer that most refer to as my lonely brain cell and the answer that came out was as follows.
Your gas valve could be sticking. If its not getting any current then its down to the pcb not sending it any. It all about your ability as an electonic wizard to detect voltage at the gas valve on the occasions it decides to act up
I then had a look at the MI's which seem to suggest that yours is actually an inset 3 as both the inset 2 models weren't fitted with a pcb. A GC number would help if you can find one. It will be something like 47 075 07

 

[bon98uk]

Thanks for that,

It is definitely an Inset 2, it says so on the boiler and the manual. To give it the full title from the manual 'Baxi Bermuda Inset 2 Boiler 50/4E'.

(The 'E' meaning it has an electronic spark igniter.)

It does have a PCB with a PCB GC no. E00-118 and a Manufacturers part no. of 237730.

You are right this could be the gas valve sticking either because it is faulty OR because the PCB is faulty (and not sending a signal).

I was hoping on the balance of experience I could narrow it down as the 'more likely' candidate.

In the end I may need to replace the PCB, Control Pot. and the Gas valve.

 

[baxpoti]

both the inset 2 models weren't fitted with a pcb.

This one was!
Baxi Bermuda Inset 2 boiler 50/4E
G.C. 44 075 33



Far more likely to be the PCB than the pot or valve, a simple test with a multimeter is all that's needed.

 

[bon98uk]

Thanks Baxpoti,

I'm suspecting the PCB but will probably replace the Control Pot as well.

The Pot does seem to measure okay on both sides of the wiper.

As this is a Back boiler the FireFront has to be removed and as this involes a spanner and gas connection as I'm not allowed to do this so I'll need to get the Heating Engineer in.