I had a new Vaillant ecoTEC plus 937 installed in the autumn. All been well, boiler runs fine etc. Heating/water running ok (still). The plastic box slides out & down, stops at an angle, do not press it all the way down, leave it be So are any of you capable of posting a picture of what the knob looks like when it is not broken ? I assume that my knobs are broken but I do not really see where it broke off from... Very strange. Not what you're looking for? Try our unique Spares Finder tool or you can view all Vaillant Boiler Spares products. Look at the box, I believe there are 4 plastic lips that you need to loosen (just tilt them over the knobs that hold them in place). Once inside you will see the socalled motherboard, or PCB. And you will see that are two round places that oppose the place where the knobs would be inserted.

Just spent 3 cold days waiting for the replacements to arrive (boiler CH dial broke in off mode) and followed carefully your guidelines. Out of warranty and there was no way I was going to spend out on a clear case of it being a manufacturing fault, on what seems to be ATM a great boiler. Had I not been able to mend it, I would have insisted that Vaillant fix it (4 year old boiler) .... I mean after spending out thousands to fit an all singing and dancing bit of hi tec kit only for the control knob to fall off! The VAILLANT 0020048969 KNOBS GREY (PK3) is a genuine, brand new Vaillant Boiler Spares product, covered by a Vaillant Boiler Spares manufacturer's guarantee.Unclip the 4 Plastic clips on the white box: 2 on top, 2 on the sides, use your flat screwdriver again gently

I was wondering if now the boiler has been 'cool' for a long period, if the knobs were a bit snug and that contraction in some way has strained them?

VR 900/920

Now you can see the innards , you will see that where the knobs go in is really a plastic box. And this plastic box can be released from teh frame easily, no screws or anything. Then you can open the plastic box open, if you wiggle with it you will probably already hear that there is something loose inside : it's the stems of the broken off knob(s) ! Product Information: The control knob sits on one of the spindles located on the front of the appliance and allows you to manually control certain aspects of the appliances functionality. Some boilers allow you to change temperature and some even enable you to change the current function. This means the user can have the boiler generate hot water without the central heating being on and vice versa. You can also use a long piece of small square wood, shaved to fit at end, if your stem is too short (unlikely, they all break at the same place as mine) However, the reason why I even started to turn the CH dial on/off in the first place was because I could no longer trust my VRT 360f Room Thermostat after returning home after a week-end away to find that the CH was full on and the whole house was 35 degrees! Wrap lots of tape at the few milimetres on top of broken stem: TO FORM A KNOB to control temperature

Pressing the metal body in helps ease it off by hand, if not strong use screwdriver or butter knife (if you have no screwdriver) The VAILLANT 0020074963 KNOBS, CPL. GREY (PK3) is a genuine, brand new Vaillant Boiler Spares product, covered by a Vaillant Boiler Spares manufacturer's guarantee.The knob broke on me, ecotec 824. It is easy to fix, even if you are not handy or elderly or a lady who does not do DIY, most ecotec models conform to below instructions: