V3 Wireless Receiver Installation

edited December 2022 in General Questions & Topics

Hi all,

I have a quick question regarding the installation of the wireless receiver. Having taken the cover off the old programmer, I am left with the attached wiring.

The yellow cable is for my water and the blue cable is for my heating according to the old unit.

Is it just a case of putting the yellow cable to HW NO and the blue to CH NO on my V3 unit? See attached images. Many thanks!



  • Yes, you've got it right. Obviously you connect the Live and Neutral too.

  • I thought as much.

    So each time I connect and power up, it blows the 3amp fuse in the spur.

    I have checked all the connections on the unit, boiler and the patress behind it, and all are OK

    If I remove the L&N and leave yellow and blue, then the fuse doesn't blow and I get power to the boiler OK but obviously not the receiver.

    If I connect the L&N to the receiver, no power to anything and fuse blown.

    Does this mean there is an issue with the receiver?

  • It's possible there's a problem with the receiver, but it would be unusual. Have you tried connecting just the Live and Neutral to the receiver, leaving off CH NO and HW NO. If the fuse still blows, then it would suggest a faulty device.

  • Hi, yes we have just done that and it stays on... so it is only blowing a fuse when we add in the wires for CH NO and HW NO.

    Really appreciate your help here GrilledCheese!

  • I’m no spark, but from recollection, doesn’t a blown fuse indicate you’re mixing L and N somewhere?

    It’s not easy to tell from the photo of the existing wiring, but my guess is there’s a crossover there somewhere, effectively with a ‘switched neutral’ (as something has been wired the other way around - not by you, but in the existing wiring).

    Try connecting just one of the CH or HW at a time to try to narrow it down. That blue looks favourite to me. (Blue for L??)

    Take care though - no NHS at the moment!!
  • Yes I did think that could be he case but was unsure as if I put the old wired stat and receiver back into position, then it all works fine.

    Will try doing one at a time as you say to narrow it down. If it is a switched neutral, then I may need help resolving that too. Thank you
  • MrPacE
    edited December 2022
    OK so I have done that and the issue seems to be with the Blue cable for the CH as I don't blow a fuse if I don't connect it.

    Yellow for the water is fine, and boiler fires up, so it's just that Blue cable for CH that's an issue.
  • What have you done with the wiring for the old wall thermostat? Normally there's instructions to bridge the wires, so wondering if you have bridged the wrong wires.

  • On the old wall stat I have put the provided connector blocks onto the cables, picturea


  • Normally Red is live, yellow is switched live and blue is neutral. I suspect you've connected neutral and live by mistake. Try swapping yellow and blue, so you have red and yellow in the same connector.

  • Good call @GrilledCheese2 - that looks like the issue @MrPacE.

    The problem with these ago connectors is they bridge if you put in side by side, whereas most of us are use to the end to end connectors here in the UK.

    What you may then find, is you have a constant call for CH. If so, put all 3 in separate connectors
  • You are a hero!!!!!! That's worked. I just thought they were connector blocks, never really took any notice of them.

    Thank you so much, I can't begin to tell you how thankful I am!!!

    Merry Christmas!!!!

  • Just to be clear, that’s yours @GrilledCheese2

    Enjoy your heated home over Xmas, @MrPacE
  • Process of elimination DM932187... and just did as you suggested to narrow it!

    And thank you for that explanation, so if the heating is constant on, I will add the other one as they put 3 in the box :)

  • @DM932187 I think you are right about the constant heat too:

    The room stat is set to 18, and the actual temp is 24

    Radiators are very hot throughout the house

    CH light is no longer lit up, but the boiler LED number says 75 (Ariston Clas HE R)

    I think I will add that last connector on, won't do any harm will it?

  • MrPacE
    edited December 2022

    OK - so I added that last bridge so they are all on their own separate one and I don't think that works.

    Tempreture of the house is now cool and the Stat is calling for the heat but:

    Device Error and Wifi icon were flashing and when they did settle down, the CH light came on, but the boiler didn't

  • Right, let's take a step back.

    The wiring to the old stat should be L (Red), N (Blue) and SL (Yellow), so 2 in, and 1 out.

    If you connect L and SL, you will definitely create the circuit that will switch on the CH permanently, overriding your tado stat.

    If you terminate them all individually, you are merely taking the current stat circuit out of the equation (although it does still carry current, which is why it needs terminating). If the receiver is wired in properly, that should not affect performance, as the stat speaks to the receiver wirelessly.

    What's happening now though, is there is no CH connection between the wireless receiver and the boiler. (You get the CH light because the wireless stat is talking to the receiver). Which suggests the wire you're connecting into CH NO is not actually the SL to take the CH fire to the boiler (which is odd, if it was working before).

    Very hard to tell what's what from the photo of the current programmer wiring. There's a lot in there.

    Where are you at now?

  • Hi...

    I've put it back so L and SL are making that circuit, so I have heating and it's been like that for an hour...

    Set the target temp to 18

    Room stat saying = 22

    CH is NOT lit up on receiver anymore

    Radiators very hot

    CH does light up and go off. If for example, I turn the stat to a target of 25, then the CH light comes on, and if I turn target right down, it will go off.

    Hope that's clear :)

  • Yep, you've bridged it and your tado stat isn't dong anything.

    To get the stat working, you need to (2) terminate this old stat wires individually to break the CH circuit there; and (2) create the CH circuit only when the relay switches on at the receiver (CH NO triggered by the stat, wirelessly).

    You have N and L into the receiver, per the old programmer. You need to find the correct wire back out from there to continue the CH circuit (if it's not that blue, apparently coming out from the old programmer).

    I can't see what you've got there. What's happening with those connectors behind the programmer backplate? Any chance you can take the backplate off and move things out for a clearer view (no need to disconnect anything, but take a photo before, if you do)?

    Also, what's your system set up? Do you have a water cylinder, valves, pump, wiring, etc. in an airing cupboard, for instance, or is the programmer wired into a combi?

  • The bridging of the old thermostat is required for S Plan. Previously there was one switch for temperature control and a second switch for time control. Both needed to be closed for the zone valve to activate the boiler. With the new receiver doing both time and temperature control the second switch needs to be permanently closed. Try turning down the boiler temperature as I suspect the hot radiators are simply giving off extra heat after the boiler switches off. Also, with Tado being a TPI thermostat it's possible for the app to request heat even when the target temperature has been reached. Attached a drawing to show S Plan wiring for CH zone.

  • Ok, we're probably causing some confusion here now, so maybe try what @GrilledCheese2 suggests first, as there's no wiring changes needed. If that doesn't work, we'll have to take another look.

    (I'm guessing my wiring might not be S plan after all as it doesn't work as you've indicated. I do have a particularly 'creative' ex-Viessmann engineer though, so who knows what I have. He likes to make himself indispensable!)

  • Hi... it's not a combi, its an Ariston Clas HE R 24 boiler that's 4 years old and is in the kitchen right next to the receiver


    I have a water cylinder upstairs which is where the pump is

    I will take off the receiver later and get you some close up pictures. From memory there is the flex from the boiler, mains in from the fused spur next to it, and then 2x 3 core cables (Y,R,Bl)

  • Right, so @GrilledCheese2 diagram got me thinking about my wiring set up and I figured out the bridging.

    Below is a full S plan diagram. It's slightly different to the sketch above in that it's programmer to room stat but the principle is the same - both on to fire.

    As I've had tado in for 10 years, I'd forgotten that the set up back then was basically a combined stat and programmer unit wired in where the old stat was located (e.g. hallway), with an optional remote temp sensor. So applying that below, imagine the programmer is the stat and programmer 4 goes straight to wiring centre 5, with there being no room stat at all. In that set up (mine), bridging the stat wires (where the programmer is located) actually bridged the relay.

    However, in your case @MrPacE, you are simply replacing the programmer with the receiver. So, @GrilledCheese2 is right, you should need to bridge the old stat wiring. Otherwise, the SL never reaches 5 in the wiring centre, so never opens the CH valve triggering the boiler to fire.

    So assuming (logically) that you can reuse the existing wire out from programmer 4 (which we think is blue), then as @GrilledCheese2 says, it's possibly not a wiring issue. It could be any of the things Grilled mentions above, or it could be the tado learning (less likely) or even that the CH relay is stuck, in which case, when the light it on, give the receiver a couple of gentle taps. Plenty of people on here have found that miraculously fixes everything.

  • I have turned the boiler thing down as pictured and I turned down all radiators to number 1 (They all have TRV except one) and pottered about a bit...

    Room stat now saying 19, target still 17, CH not lit

    And all radiators are now cool/cold with the exception of the living room which is still very hot.

    I turned that to ZERO whilst I grabbed a shower and it is still very hot!

    So perhaps the stat/receiver are working as expected but the living room radiator is still wanting heat?

  • On the tado app, do you have ANY wavy lines next to current temp?

    If not, is the boiler running, or has it switched off?

    If it's running, is the hot water off?

    Do you have any other controllers (e.g. tado radiator stats)?

  • No wavy lines next to the current temp only the target temp, see screenshots of app...

    Boiler quiet - think off

    Water off - not scheduled to come on until 5am

    Living room radiator (This is TRV - set to Zero) still very hot, can't have hand on for more tan 10 seconds

    All other rads cold

    No other tado kit (but am gong to get the 4x TRV set...)

  • If you turn the target temp above current temp, does the boiler fire?

    So the boiler is apparently off but you have a single hot radiator?

  • The boiler is very quiet so may have been on, sorry :(

    But yes, still have the hot radiator.

    I'm going to go out to pick daughter up and will be gone about 30 minutes, whilst gone I will turn off the CH at the app, and see what happens, if anything.

    Thank you both...

  • If you've turned down/off all the manual TRVs and any of the rads are still getting heat (e.g. living room), that suggests the relevant TRV(s) is stuck open. Remove the head and push down on the pin on the valve. It should move up and down. Quite common for them to stick. Replace head and see if rad then cools down. If not, TRV possibly knackered.

    As for the boiler, next step is to confirm whether or not there's a constant call for heat.

    Check what happens at the receiver, boiler and pump when you turn CH and HW on/off. You may need to crank up target heating temp for tado to go full on. Your pump may also overrun the boiler to dissipate heat, so there may be a few minutes delay after switch off.

    For reasons discussed above, the old stat wiring is probably now correct, and as far as we've been able to tell so far, so is the receiver wiring (that pesky blue). Other causes of a constant call could be a sticking relay in the receiver, or a stuck CH valve.

    Confirm on/off reaction first, then let's take it from there.

  • Morning :)

    So I left everything off last night as I stayed at my partners, turned the power on again this morning, left tado in off mode for W/CH but the boiler still fired up and after 15 minutes or so, all radiators were cold (as they are still on 1) and the living room was hot.

    Sorted the TRV in the living room, it was stuck open, so have got that moving freely and I have put the TRV back on, turned it totally off, but the radiator is still hot and continues to be so when writing this 30 minutes later.

    As for the room stat:

    I can confirm if I increase temp, CH on receiver lights up, little light on boiler goes from orange to blue, hear the boiler fire up.

    If I turn stat down, CH light goes off, boiler light goes from blue to orange, boiler cuts out after a few minutes.

    Boiler must still be kicking in & out when I'm not watching it because of the living room radiator still baslting away, but the CH light is still off and room stat is 18.3 (target 17). The living room door is left open and the heat will be moving from there to the hall, where the stat is on the wall at present.

    I have now just brought the 4 pack of Tado Smart TRV's (Toolstation £200 - Merry Christmas to me...) but clearly not worth putting on until the boiler stops being silly!?