baxi duo tec 33 he CH problem

[bladeater]

Hi all

I have a BAXI duo tec 33 he and the CH has stoped working, the programmable stat is calling for heat and have checked this at the boiler terminals, the pump is running but the boiler will not fire up. The DHW is fine, and there are no fault code n the display. I have noticed that only the DHW led on the selector switch is lit. Having looked at the user guide it says that this is only lit when HW is been supplied to a tap. However this is always on, and the CH led is not lit. But i have never noticed the CH led been lit before while it worked, but it makes me think that it must of been!?

Any ideas would be greatly appreciated, thanks

 

[Agile]

Its a little unclear to me from what you have said whats going on.

However, I think that you have a constant demand for DHW indicated so the boiler will not provide CH.

That implies a damaged or stuck DHW demand sensor.

Unfortunately these are very recent boilers and mostly still under warrantee so I have as yet not been called to repair any.

I dont have time to peruse the manufacturers details to determine exactly what is likely to have failed but hopefully one of their service engineers will be able to tell us soon.

Are you sure its out of the warrantee?

Tony

 

[baxpoti]

How old is the boiler?

If it's under two years and it's been serviced it's covered under warranty

Have you got any leaking taps?

Could be the HALL EFFECT SENSOR has failed

 

[howmuchlonger08]

Hall Sensor has a small Red LED which lights up when tap turned on, it can be unplugged to test out.

 

[bladeater]

Thanks all for your responses!

The LED is constantly on at the hall effect sensor, i have unplugged the sensor and CH works as should. Am i right to assume that the sensor is faulty??

There are no leaking taps and the light is still on even when i isolate the CW feed to the boiler and drain off the HW taps.

However when i move the sensor from its position (parallel to the plate heat exchanger) the LED goes out, then back on when back in position?? As i do not know how the hall effect sensor is meant to work, i'm not sure if it is faulty or not!

 

[Vic Spanner]

The magnet inside the brass body is stuck up , Probally by a bit of grit, Can be undone and stripped/Cleaned.

1. Turn Cold Water off.
2. Remove Sensor
3. Undo brass bit the sensor sits on with a small adjustable.
4. Clean/Repair

 

[Agile]

Is that brass bit the one with rounded off corners which is sometimes a pain to undo?

 

[bladeater]

Cheers poxi!

I have removed and rinsed through, but still jamming. However a slight tap on the restricter body frees it. I know this is not ideal but at least i know what the problem is!
I'll try cleaning it again, any tips.. silicone spray or compressed air line etc?? Or could it just be that the spring has had it and a new restricter is required?

Thanks again

 

[Vic Spanner]

With the body out, You can undo the whole lot and dismantle. It is normally the plastic bit that the magnet catches, This is what you need to clean or smooth off with a stanley blade.

 

[Vic Spanner]

Is that brass bit the one with rounded off corners which is sometimes a pain to undo?

Sorry, never had any problems myself. (Strong right hand )

 

[Agile]

When you take it apart look closely at the inner plastic bit.

They often have excessively wide moulding lines.

These can be removed with a file or simply by scraping them with a stanley blade.

Tony

 

[DunhamMS]

I was having this same exact issue 100%. I have dumped $1500 into unnecessary repairs suggested by Technicians who are unfamiliar with the unit and just basically throwing parts at it. I stumbled across this thread today and we had it diagnosed and repaired in three hours (ourselves). Just wanted to say THANK YOU!!