# Viessmann Vitodens 100 W Condensing Gas Boiler - Help Needed



## daithi69 (5 Jan 2011)

Hi 

We have just had this boiler installed by our plumber and because of our budget all that we could afford was to get the plumber to supply and install was the boiler. We are very happy with his work.

I have had to complete the rest of the zoning system myself (electrical only - i am not a plumber)

Everything, thermostats, zone valves, and time clock are all working. The only problem I have is how to tell the boiler to turn on and off. In the wiring diagram it shows that you supply the boiler via the zone valves but I feel that the wiring from the zone valves is a little light for the job.

After a little reading online I found that a lot of boilers have a permanent mains supply with a seperate feed from the zone valve to turn the boiler on and off.

Is this the case with this boiler? I cannot find any reference online how this should be implemented.

I have spoken with the plumber about this but he does not do the electrical work himself. He can get someone but at a cost. Unfortunately our budget does not allow this at the moment.

link to wiring diagram - hxxp://db.tt/QqnutXa (replace hxxp with http)

Any help / advice appreciated.


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## Barney Magoo (6 Jan 2011)

Hi Dave,
Our plumber recently installed this Boiler for us too. He installed a Sauter T27 - 2 Zone Programmer to deal with automatic and manual switching on/off of the boiler. 
Like this: 
I suspect you may need an electrician to fit it, though. 
Not sure if this is what you need  as you say that you have a time clock associated with the boiler, so maybe you have something similar already.


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## Shane007 (6 Jan 2011)

Should be wired as follows:
Timeclock wired to room stat, room stat wired to motorized valve and then motorized valve wired to boiler and circulating pump. Wiring in this way is called "boiler interlock". It ensures that only the motorized valve can fire the boiler and switch on the circulating pump so that there is always an open circuit when boiler and pump are on. Make sure you have 2 x 3amp fused switches to boiler and pump. You should really get a qualifed electrican to do this as if you blow the circuit board in the boiler, you will have invalidated the warranty.


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## daithi69 (6 Jan 2011)

Thanks for your reply Barney Magoo and Shane007.

I have a 4 channel Horstman H47XL installed and all circuits, timeclock, stats, zone valves, and boiler/pump are all protected by 3A fuses.

Shane007, I have everything wired as you have described above. Regarding the pump and boiler the plumber did say that the pump was integrated in the boiler, In other words I dont have a seperate pump! There is also a 2.5A fuse inside the boiler itself.

I do understand the importance of using a qualified electrician its just our budget ran out and it has been a little cold lately. With heating no working properly we have were not left with much choice we had to get it working.

I could probably go back to Heatmerchants where I bought the zone valves and see if they can tell me if it is ok to take a live feed straight of the zone valve to power the boiler. Failing this I will have to give the electrician a call.

Thanks for your help


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## Shane007 (6 Jan 2011)

No probs. Sorry but I am not an electrician. If you PM me, I can give you the number of my electrician and he can talk you through it over the phone.


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## DGOBS (6 Jan 2011)

The boiler will require a 'permanent' live supply directly from the 3amp spur (manual page 43 - connnector block 40 live/neutral), there will also be a another set of 'permanent' lives from the spur to the auxillary on the MV's (grey wire) when this closes (ie. the zone operates) the live on the grey returns on the 'switched' live (orange wire) this will come back into the boiler to signal it to fire up (look at you manual page 43 - it goes into the 'LR' on block 56)

Incase your wondering what the rest of block 56 is for, you can use the L/N to power the programmer and provide neutrals to stats/MVs aswell, LS can be used as supply to the MV grey auxillary as above, LR then returns on the orange wire

If your looking for some wiring diagrams, goole 'S plan diagrams for central heating' it will give you a layout of a 2 channel system


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