Danfoss to Drayton Wiser

[pveeuk]

Hi All,
I have a vented heating system where a Danfoss thermostat controller is used to schedule the central heating and hot water. I have two zones—upstairs and downstairs—which I turned to the maximum setting of 30°C so that they are always on.

When I opened the Danfoss controller, I saw that 4 wires (excluding the earth wire) are connected in the following order: N, L, 3, and 4.

I have attached an image of the backplate and the back of the Danfoss controller.

I replaced the Danfoss controller with a Drayton Wiser hub (from Kit 3) and set up the app. In the app, I can turn on the heating or hot water, and I can see the heating light on the controller when it is turned on, but the boiler is not firing.

However, if I click on one of the heating controls in the app, I can see the boiler starting (though I have not checked whether the radiators are getting hot).

Can you help me identify and fix the issue?

 

[ericmark]

There are three versions of drayton wiser, it seems you have fitted the three channel version and wired as for two channel version, but this is only a guess. You have not said what boiler is used, OpenTherm

uses the wires shown here.

The whole idea of boiler control is aimed at allowing the boiler to gain the extra 11% of energy by gaining the latent heat from flue gases, as to how this is done, depends on the boiler, my oil boiler does not gain the latent heat, it simply switches off/on, but most gas boilers will modulate (turn down) to gain the latent heat, in the main this is done with analogue control.

The wall thermostat is more like a hub than a thermostat, gathering info from the TRV heads to know when to turn on the boiler and motorised valves. Since I don't have Opentherm I have not really studied it, however it seems the motorised valves and boiler is independently controlled. I can't get my head around the idea of zoning zones. I would have thought with motorised TRV's there is little point in also having motorised valves.

 

[CBW]

Can you post a photo of the wiring?

 

[pveeuk]

thanks eric, chris for the reply
Chris this is the wiring diagram and the image of the boiler set up

 

[CBW]

Can you also post one of how you wired the Wiser?

 

[pveeuk]

thanks Chris for the quick reply.. for a start I havent done any wiring at all.. just removed the existing Danfoss controller from the backplate and put the wiser controller and then set up the app where in the app - selected gas boiler and the boiler type is standard"

 

[CBW]

thanks Chris for the quick reply.. for a start I havent done any wiring at all.. just removed the existing Danfoss controller from the backplate and put the wiser controller and then set up the app where in the app - selected gas boiler and the boiler type is standard"

Well, herein lies your problem, if it is indeed a kit 3. Terminal 4 isn’t used. You would need to alter the wiring. Doing what you have done will only work on a Kit 2, which oddly your Danfoss only is but works 2 heating zones and a hot water?

 

[pveeuk]

thanks Chris,
yes I got Wiser kit 3 without checking the wiring because my previous owner installed the heating system with two temp controls - one upstairs and down dowstairs - thought its a multizone set up. so you reckon best to get the kit2 to avoid rewiring ? I guess its working like a single zone then ?

or rewire to use kit3 ? is it complicated to do this rewiring or need a professional to do it ?

 

[CBW]

Being a 2 story house it should be fairly simple. You would need to mount the Wiser receiver near the wiring Center for best results. Do you know if there’s a single timer too?

 

[RandomGrinch]

or rewire to use kit3 ? is it complicated to do this rewiring or need a professional to do it ?

It would be a relatively straightforward task to connect the Wiser up to the wiring centre in the loft.
However, that would leave a few obsolete cables - disconnecting and tidying up these safely, may take a little more competence.
Also, should the Hub need attention, it would be hidden away in the loft!

If I understand your setup, your Danfoss FP7898 is the programmer for H/W and C/H, and you have separate thermostats for the two zones?

From your images, I believe to wire up the Wiser, you would take an L, N and E from the wiring centre to power the Hub.

You then need to follow the Brown wires from the zone valves - the heating valves appear to connect to terminals 2 and 4, these would connect to terminals 1 and 3 on the Wiser - it doesn't matter which - the names of the zones can be changed from the app.
For H/W, the brown from the zone valve connects to terminal 16 of the wiring centre, then to the blue wire in the tank stat.
The brown wire from the tank stat connects to terminal 1 in the wiring centre.
This is where you would connect Wiser terminal 2.

If that sounds a bit like gobbledygook, you may need to get an electrician in!

 

[pveeuk]

thnaks for the reply

CBW,​

Being a 2 story house it should be fairly simple. You would need to mount the Wiser receiver near the wiring Center for best results. Do you know if there’s a single timer too?


sorry "single timer" I am not familiar with the entire boiler set up in my new house - first vented system I have.

two temparature controls - one upstairs and one downstairs
controller - which I can schedule CH or hot water on off times

so wiser kit 2 can only control one zone or entire house with a schedule + hot water schedule
kit 3 can control two zone CH + hot water schedule BUT IT REQUIRES SOME REWIRING from the existing set up

RandomGrinch​

it doesnt look so complicated (but not simple either for me).. I can give a go on the wk end or call someone to help

 

[CBW]

Looking back through your photos, you don’t have a vented system. It’s an unvented cylinder for hot water with a boiler to heat hot water and central heating, although the heating could be open vented. A single time clock/timer maybe in use or a programmable room thermostat as you do have 2 heating zones, but perhaps it is only off the thermostat.

 

[pveeuk]

thanks Chris for the correction, its unvented heating (ie not with an overhead cold water tank isntit ?, mistook expansion vessel on the hotwater cylinder) sorry new to the heating systems. still learning how it works - thought I give it a go if its not too complex with the help of you guys + with my electronics and basic electrical background, much appreciated

attached room thermostat image (two of them one upstairs, one downstairs) and existing danfoss controller.

from the replies above I think I have to re-wire to get the kit3 working - I can parallelly do the connection without removing the existing connections to the central console to make sure its working!
but it would be great if you give me a diagram or plan to re-wire to make it working before I call an expert. thanks

 

[RandomGrinch]

but it would be great if you give me a diagram or plan to re-wire to make it working before I call an expert. thanks

As above...

From your images, I believe to wire up the Wiser, you would take an L, N and E from the wiring centre to power the Hub.

You then need to follow the Brown wires from the zone valves - the heating valves appear to connect to terminals 2 and 4, these would connect to terminals 1 and 3 on the Wiser - it doesn't matter which - the names of the zones can be changed from the app.
For H/W, the brown from the zone valve connects to terminal 16 of the wiring centre, then to the blue wire in the tank stat.
The brown wire from the tank stat connects to terminal 1 in the wiring centre.
This is where you would connect Wiser terminal 2.

For testing purposes, you can connect the Wiser as above, leaving the existing wires in place. You will need to replace the FP7898 back on it's backplate, but set both H/W and C/H to off.

Alternatively, if you are happy having a single zone system -
Turn both existing thermostats up to maximum.
Move the black wire in terminal 3 to terminal 2 on the FP7898 backplate.
Move the white wire from terminal 4 to terminal 1.
Then replace the Wiser.

 

[pveeuk]

thanks so much RandomGrinch,where can I send a few bottles of beer

the diagram, really helpful for my wk end project. I will update here how it goes.

thanks to Chris too