Pressure Sensor Vaillant ecotec plus 824

4 Feb 2012
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United Kingdom
I am replacing the orange pressure sensor on the Vaillant Ecotec Plus 824 with the new black pressure sensor, however the fitment seems much too loose on the black pressure sensor.

The black pressure sensor has come with a thin locking pin, the washer, the sensor and another thicker locking pin. I can see where the washer, the sensor and the thin locking pin can be fitted but what am I to do with the thick locking pin, if anything at all?

It seems that the fitment on the orange sensor fits snugly into the hole whereas the new black pressure sensor seems to just sit in the hole and has quite a bit of movement, even with the think locking bit in place. I have put a picture of the pressure sensor that i am trying to fit - is this the right one?
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The requirement is to seal the joint and thats all thats required.

It looks like the correct part.

As both clips are provided I can only assume that both types are used on different boilers and presumably you need the same one that was used with the pink sensor.

One wonders what you hope to achieve by changing the sensor for the black one.

All done - I thought the same as well - the thicker pin is for another type of fitting

Although it seems lose, it is sealed and running fine.

Had a f.75 error, changed the pump and was resolved - however noticed that the Pressure was building consistently to more than 3 bar and staying in the red on the indicator when heating was on. Changing the pressure sensor seemed like a simple do it yourself job with no gas parts to replace. I also read that the orange sensor was prone to being faulty in these models therefore wanted to be sure that it doesn't cause the pump to fail again

thanks for your advice.
The pressure going up to 3 bar sounds more like an expansion vessel fault.
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