Vailant 831 eco tech boiler not working with thermostat

[su C]

Hi, I have a vailant 831 boiler and sylus thermostat. This boiler is the one with the timer.

1. When I increase the temperature above the room temperature on the thermostat I can see the green light turning up on the reciever.
- this is to confirm that the pairing between the thermostat and reciever is fine.

2. When I turn the knob of my boiler to the radiator, it switches on the heating irrespective of what the temperature is on the thermostat.
Even if the temperature set on thermostat is set to lower than the room temperature, I see the boiler starts to heat up the radiator.

Am I doing something wrong or would you suggest me to try out anything.

Thanks for your help!

 

[jj4091]

Unless you can just get the relay (receiver) for your thermostat, it would seem you will need to replace both the stat. and the relay (receiver) as it sounds like the relay has gone short circuit.

 

[danfre]

It could be a wiring issue.
Sometimes installers forget to remove link between no 3 and 4.
Worth checking

 

[su C]

It could be a wiring issue.
Sometimes installers forget to remove link between no 3 and 4.
Worth checking

Would this link be in the reciever or within the boiler?

 

[Deleted member 267285]

Would this link be in the reciever or within the boiler?

In the boiler, but often 3 and 4 are used anyway. Sounds like the thermostat may not be connected at the boiler end, or has been linked out.

 

[su C]

Thanks. I ll check that and keep you informed.

 

[su C]

I checked my boiler today. And here are some of the images-

1. The reciever wiring:

The L and Com are connected to the live wire within the boiler.

2. The wiring within the boiler:

3. I see a loop connection on the 24V rt. Should I remove this loop?

Any thoughts what might be going wrong? Thanks in advance for all your help!

 

[ericmark]

I tried to look for the boiler manual at first found wrong one, but when I did find one which seems to match pictures it does give some warning.

It says how the 24 volts and eBus must be independent cables from the 230 volt cables, including coming out of the boiler on different sides.

It seems nothing is connected to your extra low voltage connections. So you are looking at page 37. This is an unusual instruction

However reading the instructions it says

this makes me think the termial block is room sealed, yes I agree a silly idea, but I would say you need a gas safe registored person with the equipment to test to ensure the seal is intact before running the boiler again, as an electrical engineer that 9 rings alarm bells, and I would simply walk away and say it needs a gas safe person to work on it.

I am sure some one will come and confirm or otherwise to if on this boiler one can access the wiring.

 

[su C]

I tried to look for the boiler manual at first found wrong one, but when I did find one which seems to match pictures it does give some warning. View attachment 350003 It says how the 24 volts and eBus must be independent cables from the 230 volt cables, including coming out of the boiler on different sides. View attachment 350004It seems nothing is connected to your extra low voltage connections. So you are looking at page 37. This is an unusual instruction View attachment 350005 View attachment 350006 View attachment 350008 However reading the instructions it says View attachment 350009 this makes me think the termial block is room sealed, yes I agree a silly idea, but I would say you need a gas safe registored person with the equipment to test to ensure the seal is intact before running the boiler again, as an electrical engineer that 9 rings alarm bells, and I would simply walk away and say it needs a gas safe person to work on it.

I am sure some one will come and confirm or otherwise to if on this boiler one can access the wiring.

Thanks. I think I got my hand on the right manual now. Below is the screenshot of the same-

I see my thermostat reciever is connected to 230v within the boiler. Should I try to remove the 24v rt and hope the thermostat to work fine?

 

[su C]

I retried after removing the 24v rt loop. The thermostat is working as expected. Thank you all!