External controls for Vaillant combi

[LCD]

Hi have just installed a new Vaillant Ecotec Plus 831. Normally when I wire in a Honeywell CMT 927 programmable room stat. to the Ecotecs, it is straight forward, however, Vaillant have changed their internal wiring. Although the Honeywell receiver is picking up the signal, the boiler is running on heating constantly. I phoned Vaillant but they didn't answer after 15 mins, phoned Honeywell. The guy was really helpful, he said to put a link between the 2nd Live and A on the receiver, and just have B wired to the 230V RT on the boiler. Well, I did this and the boiler still just ran constant on heating, disregarding the programmer. The little green light clicks on the receiver when I increase the temp, however the boiler still runs on heating continuously prior to this. Somehow I think these boilers have become too complicated, or they're being produced for computer experts to install. Anyway, I'm hoping someone on this forum has encountered the same problem and can explain the wiring for 230V external controls.

 

[andyg0507]

i take you are gsr??

Theres no need to wire it on the 240v side aswell, you can just wire it to the 24v side, much easier and much safer inmho

 

[LCD]

What's gsr? Yes, of course I am. I haven't ever wired a Honeywell control to 24V. They've always worked by following the wiring diagram. It's just the new Vaillants that are different. Apparently (so I was told), this problem is being encountered by a lot of installers so I'm hoping someone out there will shed light on the subject. The installation manual doesn't give specific info about external controls.

 

[andyg0507]

is it the wireless cm 927 your trying to install?

 

[LCD]

is it the wireless cm 927 your trying to install?

Yes it's the wireless one. The receiver L & N is wired in to the fused switch load along with the boiler L & N.

 

[moogwai]

How have you wired it? I normally stick the wires from the stat side of things into the 240 live and the switch live and then remove the 24v link.....worked everytime for me so far.....had the same problem when i first wired a 927 into the new ecotec and the vaillant tech guy i spoke to was very good.

Also rebind the the 927 with the receiver.

Sent from my GT-I9100 using Tapatalk 2

 

[LCD]

Thanks, I never removed the 24V link - that would explain the continuous firing up. Will go to it fresh tomorrow and try to contact Vaillant tech. again.

 

[moogwai]

I would say that is definately the problem mate.

Sent from my GT-I9100 using Tapatalk 2

 

[stevetheplumber]

i did the same book is very unclear you have to remove the link on the 24v terminals rt

 

[Rickster123]

I had exactly the same this week too. Liking the new look vaillant tho.

 

[LCD]

I had exactly the same this week too. Liking the new look vaillant tho.

Marvellous - it worked! I removed the 24V link. Hadn't wanted to touch it as I thought it would have no relation to the 230V connections. Makes sense when you think about it. Installation manual is pretty unhelpful regarding external controls so thanks to this forum and Honeywell Tech. Yes - nice boiler - another satisfied customer.
Thank you all!