Drayton Wiser to Vaillant boiler

[NackJich]

Hi there..
When wiring the universal backplate, would you take the live and neutral feed from the boiler circuit board or would you wire it separately from a junction box?
I've seen both methods described, and wonder which is best practice (if any)? Thanks...

 

[harrythefurrysquid]

I'd take it from the junction box, which should have a 3 amp fuse.

Not sure it matters that much though as long as it's a reliable power supply.

 

[ian1182]

The boiler, programmer, pump and other heating controls should be fed from a common source which is protected by a 3A fuse. Generally that would be a fused spur located near the boiler. The intent is that the entire CH system can be isolated from a single location for safety purposes.

Taking the L, N & E connections from the boiler is OK but that may not be the best choice.

What controls does the boiler currently have?

 

[NackJich]

Thanks Harry and Ian. I have followed your advice and my mounting plate is now live. I fed it from the existing fused wall mounted box that serves the boiler. Currently the boiler is controlled by a cheap and nasty wired thermostat in the hall. TUV? At least it's programmable!

 

[ian1182]

Sounds like good progress. You just need to wire up the control side now and bypass current thermostat

 

[NackJich]

I just need a little more help and advice please. This seems to be switched by 240v. In the photo the originally mis-labelled 24v block is wire free, and the cable coming from my old thermostat goes into the purple block. I might just use that cable for my purposes. I gather L and 1 on the mounting plate now have to be connected, but I'm unsure where my feed wires need to go. Is it 1 & 3? I was expecting a low volt switch but I can't tell you why!

 

[ian1182]

Just checking you have the 1-channel version of the Wiser. If so..

Easiest is to use the existing cable going into the purple block and connect the other end into 1 & 3 on the Wiser. Whilst it does not matter which way round the cable goes on the Wiser, I would recommend brown into 1 & blue into 3. Then add a brown sleeve on the blue to say it's a "switched live". This will leave Wiser terminals 1 & 3 as potential free, i.e. no voltage is being added by the Wiser Hub. It is merely closing the circuit between 1 & 3 when "on" and opening the circuit when "off". You should NOT bridge L & 1 on the Wiser.

If you look at the Vaillant installation instructions, the 24V block is not mis-labelled. The crossed out 230V is intentional. See page 23

https://www.vaillant.co.uk/downloads/z/ecomax/ecomax-use-installation-and-servicing-manual-261444.pdf

Another thing I would check is any strain on the cables going into light blue (L/N/E) and purple (3/4/5) ports as they do seem to be at a bit of an angle.

I should have enquired before, presumably your existing cheap and nasty wired thermostat is battery powered?

 

[ericmark]

Wiser single channel is volt free, and can have an opentherm module, but the double and triple channel can only work at low voltage (230 volt) I personally think using the same back plate for all three is wrong, it is asking for problems, however it has been done like that for years, by many thermostat and programmer manufacturers not just Drayton.

The idea of using the same circuit for all 230 volt central heating items seems good, but a circuit is an assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s), so if there is a fuse inside the boiler, then to be the same circuit means it needs to be supplied from the boiler, however a supply, is what runs the whole house, so it will always be the same supply.

As @ian1182 says "The intent is that the entire CH system can be isolated from a single location for safety purposes." but this is only really a problem when not using a volt free thermostat, the Nest thermostats are often supplied from a separate step down power supply, or USB module, but really there is no difference to if the power supply is integral or separate, if the contacts are volt free, it does not matter if supplied from same circuit or not. Only when using the non volt free is there a problem, one expects if you turn some thing off, then there is nothing live after that point.

The problem comes when volt free is replaced with non volt free, but one can't stop those who come after you not to do some thing daft.

 

[NackJich]

Well where would we be without the generous contribution of you guys? I followed the suggestions and everything worked on start up. It was incredible! I watched hours and hours of YouTube videos and none seemed to match my circumstances exactly. All he background info is very interesting too. I might just summarise the steps I took for the benefit of others faced with the same task:

Vaillant Ecomax 828/2 Drayton Wiser Thermostat Kit 1
1) Install the mounting plate using a spirit level. Leave a fair clearance under it to allow for screwdriver access. I fixed mine to the wall, 2 ft from my boiler.
2) Break off a couple of plastic pieces at the lower end of the mounting plate to allow the wires to pass
3) Mount your WiFi thermostat. Mine is at shoulder height on the upper floor landing not too far from the boiler cupboard, but not near the radiator - obviously.
All the rest of this: TURN YOUR MAINS OFF ****
4) Run a mains supply cable to terminals N and L of the junction box. Attach the Earth wire. I used the existing fused outlet that supplies the boiler.
5) Open the case. One large screw in the middle and then two silver tabs to either side of the screw must be pressed to release the case.
6) Circuit board housing has two plastic lugs that if you release, the whole thing hinges forward.
7) I didn't touch anything on the board in the end. I left the the original thermostat wire within the boiler in place and cut it to length and attached the brown wire to terminal "1" and the blue wire to terminal "3". Please check the other posts here for some improved practices! My thermostat wire was just 2-core. Brown and blue wires. I did NOT link terminals L and 1
8) Attach the receiver to the mounting plate and secure with screws. Rebuild your boiler.
9) Switch on your mains.
10) Download the App to your phone and follow instructions for WIFI set up
11) Fit batteries to your thermostat and pair it. The whole process worked painlessly for me.

pls note that I have no technical knowledge, and can not take any responsibility for mishaps. This is just what worked for me!

 

[NackJich]

Ian thanks, I can see that the crossing out is in fact a warning!! I think I do have the one channel version. I selected Combi boiler at purchase...

 

[ian1182]

That is good to hear that it's all working fine. You can easily tell if its a 1-channel model by looking at the number of buttons on the right hand side. The 1 channel model has a single button labelled "Heating" whilst the 2 & 3 channel models have "Hot Water" & "Heating" buttons. They all have a setup button to the left.

You just have the fun of setting up your CH schedules. I'd recommend a careful read on the pros/cons of Comfort & Eco modes as that caught me out initially. Basically comfort mode brings the heating on early to achieve the desired temperature by your nominal on-time, whilst eco does the opposite at the end of the on period. Comfort mode works well for me but I found eco cut the heating earlier than I wished. So strangely enough something like this works for me

00:30 17C
08:00 21C
09:30 20C
17:00 21C
23:00 19C

I'm in the house all day, hence maintaining the temp during the 9-5 period. With a 19C at 11pm & 17C at 00:30 that means the heating cuts out around 10pm. When I initially set 17C at 11pm the heating went off at 20:30-21:00 ish which was not the aim. But your mileage may vary.

 

[Mister Banks]

That is good to hear that it's all working fine. You can easily tell if its a 1-channel model by looking at the number of buttons on the right hand side. The 1 channel model has a single button labelled "Heating" whilst the 2 & 3 channel models have "Hot Water" & "Heating" buttons. They all have a setup button to the left.

You just have the fun of setting up your CH schedules. I'd recommend a careful read on the pros/cons of Comfort & Eco modes as that caught me out initially. Basically comfort mode brings the heating on early to achieve the desired temperature by your nominal on-time, whilst eco does the opposite at the end of the on period. Comfort mode works well for me but I found eco cut the heating earlier than I wished. So strangely enough something like this works for me

00:30 17C
08:00 21C
09:30 20C
17:00 21C
23:00 19C

I'm in the house all day, hence maintaining the temp during the 9-5 period. With a 19C at 11pm & 17C at 00:30 that means the heating cuts out around 10pm. When I initially set 17C at 11pm the heating went off at 20:30-21:00 ish which was not the aim. But your mileage may vary.

Why not turn eco mode off and set the off events to the actual times you want to go to the setback temperature? I think doing it the way you are is skewing eco mode and any savings reported will be incorrect.

 

[ian1182]

Why not turn eco mode off and set the off events to the actual times you want to go to the setback temperature? I think doing it the way you are is skewing eco mode and any savings reported will be incorrect.

I feel there is some benefit from the variability that eco mode provides on the actual time the set point is lowered based on external temperature, etc. Turning off eco mode and moving the reduction to 17C at 10pm makes it a fixed time. Perhaps I need to do some analysis of the times the setpoint changes to see if I'm over complicating the situation. You may well be correct.

 

[NackJich]

Yes I'm sure mine is the one channel model. I have just finished programming it so fingers crossed. So far it's doing all the right things. Mine is set on 16 degrees with 12 degrees in the OFF periods. Maybe it's my Scottish ancestry (on my mother's side). I'm not averse to wearing coats around the house, and sometimes a scarf! I do find that as Winter sets in I'm much more tolerant to cold. Anyway I digress.. I'm following the discussion with interest... now I just need to kit some of my radiators out with the special valves.

 

[Mister Banks]

I feel there is some benefit from the variability that eco mode provides on the actual time the set point is lowered based on external temperature, etc. Turning off eco mode and moving the reduction to 17C at 10pm makes it a fixed time. Perhaps I need to do some analysis of the times the setpoint changes to see if I'm over complicating the situation. You may well be correct.

I'm not an expert, only had Wiser for a few weeks, so I am still investigating how eco mode actually works. I think eco mode switches the heating off early if it deduces that the setpoint temperature will be maintained until the next setpoint. To do this Wiser needs to understand how quickly the room/house cools down and what the outside temperature is. I could be wrong!