Baxi duo tech constantly heating

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Lwjm18

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Hello all

Working on a 10 yo duotec 28. It's constantly heating radiators. The CH light at 10 o'clock is constantly lit.

I have replaced with new:
Stat/timer + receiver
Diverter valve cartridge (original in great condition)
Diverter valve actuator - which moves nicely up and down

I feel like I'm missing something.

Any tips?

Thanks

Lee
 
Stuck flow sensor?

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and paste in:

"Why is baxi duotec 28 constantly heating water?"
 
Can you post some photos of the wiring? So you have zonal heating? Sounds like something is sending a switch live to the boiler. Any changes recently, apart from what you've said?
 
power off drop front panel remove cover from back go to terminal strip and remove one of wires (position 1 and 2 with black wires) that goes to external controls make safe then turn your power back on if the ch demands light stays on it is a boiler fault if its no longer on you have an external.

fault.


.if it stays on it maybe a faulty sensor making the boiler think it is cold and is in frost protection mode change sensor in dry pocket on pipe on left hand side part number 5114725
have you got an external frost stat ?

.
combustion box is not breeched in anyway before mods start having kittens
 
Last edited:
Thanks for the help so far. Wiring is entirely conventional. No zones.

I've put some pictures up as requested, so if they give something away that I haven't spotted, that's great.
1000050063.jpg
1000050064.jpg
1000050065.jpg
1000050066.jpg
 
Thanks, that doesn’t show the wiring I’m after, it’s under the terminal block. However the advise from @gas112 is great for you to try. Hard to tell exactly, but that actuator looks different
 
gas112 said:
power off drop front panel remove cover from back go to terminal strip and remove one of wires (position 1 and 2 with black wires) that goes to external controls make safe then turn your power back on if the ch demands light stays on it is a boiler fault if its no longer on you have an external.

fault.


.if it stays on it maybe a faulty sensor making the boiler think it is cold and is in frost protection mode change sensor in dry pocket on pipe on left hand side part number 5114725
have you got an external frost stat ?

.
combustion box is not breeched in anyway before mods start having kittens
Click to expand...
Nowhere near anything combustion related!

OK. Will try with removing a black/live from block in pic 4 and report back. Thanks all for offering advice.
 
Lwjm18 said:
Nowhere near anything combustion related!

OK. Will try with removing a black/live from block in pic 4 and report back.
Click to expand...
No need to do that, you have a link fitted. Do you have an integral timer?
 
Stuckinarut said:
Can you post some photos of the wiring? So you have zonal heating? Sounds like something is sending a switch live to the boiler. Any changes recently, apart from what you've said?
Click to expand...
Actuator is identical to the old one, which was also working well ist seems:
1000050067.jpg


And here's the block - sorry for being thick

1000050066.jpg
 
Are you registered?
I now see that you mention replacing the thermostat/timer/receiver but the factory link is still in place. The boiler is working as expected.
 
@Lwjm18 - you’re not being thick, and thanks for additional photos, this confirms you have a Salus receiver that connects where the mechanical time clock would sit.

Yes the motor is the correct one, just looked different on the other photo.

Check the Salus isn’t set to manual.
 
Gas... we've had plenty of illegal workers on here asking questions.

Indeed, I now see he's using a wireless Salus timer/stat so the link stays in place.
 
With your pics of wiring now up take out the yellow link if it stays on then boiler thinks its in frost protection mode
 

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