Drayton Digistat SCR - appears to have been by passed

[M7R]

when we moved in to our new house I noticed there was no wall mounted thermostat, in the airing cupboard is conroller for a Drayton Digi stat which was fitted when the new boiler and Drayton controller was fitted back in 2008... I asked the previous owner where the wall mounted stat had gone (I was sure I had seen one when we viewed the house) and she said it had been by passed when the new boiler was installed and she was told to just contol the temp via the boiler.. now this seems odd as its appears that the stat was fitted when the system was installed so it must have been by passed later on ( she was getting on a bit, and was confused by a few things so it sound't suprise me)

I did buy a new wall stat before I knew it had been by passed, but I coud not get it to pair up, and now it seems it may have been by passed...(the box just has a red light for alarm lit up, it can be put into learn mode but this doesn't seem to work)

any idea how to un do the by pass? or am i going to have to pay some one? (I have a friend who is a sparky so I am sure we can re wire if we know how it should be done)

Karl

 

[Puddle]

Well it could have been by passed in a few ways,if you remove the receiver box there should be wires between 1 and 3 which is the switching loop,if you see two wires connected to 1 or 3 and the other terminal empty ,this is probably how it has been by passed,so split the wires between terminals 1 and 3 again,if wires are in place,trace wiring back

what boiler make model do you have ?

 

[M7R]

ahh brill I ill pop the cover off tomorrow eve (not dug into this yet as the wife shouts each time I take something apart lol)

Its a Visseman Vitodens 100W, I am trying to sort out a few other little issues with the set up at the moment so hopefully soon it will be all sorted.

 

[jtsplumbing]

What boiler do you have ? they may just have fitted the wireing loop back into the boiler, or they have linked wires together in the receiver, have you got information on how to pair them ??

 

[southcoastboile]

mabee even just lost its signal, never tried pairing a new stat with old reciever as they always come as a pair,i take it it is wireless, do you no what make and model it is, it is tricky to get them to reset as the procedure is long and explained very badly in the instructions on some models. If permanant red led then it has lost signal although as others have said may be linked out, they may have just put a link wire, if there is a wire in the reciever going to more than 1 terminal then remove it.

 

[M7R]

i have instructions how to pair them, so I know somethings not right. there are wires going into and out of the reciever so I am guessing it has been bypassed internally, (it has power going to it as the alarm light is lit up)

 

[M7R]

heres the wiring

which one should go back into 3?

 

[danielp]

your receiver and stat will have lost its signal, buy a replacement pack the new receiver will go onto the old back plate so no need to rewire pair them up as per instructions normally hold button 2 then 1 at the same time the red light will flash this is in learn mode with the battery draw out of the unit push it back in the red led will flash for a further 7 seconds it should now be paired, go to the boiler control wiring and no doubt they have wired a link in between permanent live and L1 remove it and job done, hope this helps

 

[M7R]

are you sure? as there should be a wire in port 3, (the 5th one along, where the screw is partly out and the clamp plate is bent like there used to be a wire in there) and there are 2 wires in port 1 (3rd one along) so I need to know which one from port 1 needs to come out and go in 3,

I could still have the wrong thermostat as the reciever maybe on the old frequency, however I want to get the wiring sorted first.

 

[jtsplumbing]

Hi looking at what you have sent i think what you have is ; mains supply in / is center cable N.L E , right hand cable is supply to boiler N.L. yellow has been used as E. Left hand cable is switch`d supply to boiler Brown wire into No 1 (3td from left) Blue wire into No 3 (5th from left) These two wires together will give permanent supply to boiler

 

[M7R]

cool, so if I put the blue in number 3 (the 5th port) then I should be fine and dandy? (I have just checked my stat and it turns out it is a wired one with battery back up! so a proper wireless one will be ordered today)

what would happen if the wires in 1 and 3 were the wrong way round? just encase it is wrong?

 

[jtsplumbing]

Nothing ! 1 & 3 is supply from and to boiler it switches accross in reciver, gets power from boiler.

 

[M7R]

Nothing ! 1 & 3 is supply from and to boiler it switches accross in reciver, gets power from boiler.

brill I just wanted to make sure it wasn't sensive to polarity.

I have now ordered a new reciever and proper RF wireless stat model, so that will be fitted as soon as it arrives. I have been told this will also help cut my gas bills a smidge, and maybe help with my other issue of the noisey pump due to it kettling.

 

[M7R]

Right answers on a post card! I have now got my new stat an controller... the same models as what I have down stairs in a box, so it wasn't looking promising... I have put the blue wire in to number 3 as instructed above, turned everything back on, the red light came on on the SCR box as it should..the pump started running and then a min later the boiler fired!!!! so any idea where else to look for the scr being bypassed? as I am now annoyed and stumped

 

[jtsplumbing]

can you send photo of wireing block on boiler ?

 

[M7R]

just stripped the main power unit to check wiring in there, and then took the boiler apart to get to the power block in there and found this!!!

no wonder it doesnt work!

heres how the install says it should be wired:

However I will now post a pic of the main power box as it does not go to the right place in there it seems

 

[M7R]

The black block is port 56 btw,

the 1 connected wire from that goes down to port 12 which says BLR

traced wire back from block 56 has 1 black dot, I ma now tracing the others to see where they go:

 

[M7R]

the timer is a Draton LP112 btw,

I have just traced the wired back from the main power box, from ports 2 and 3, and they go into the SCR control box ports 1 and 3, the correct way round for com and call,

so I guess the problem is between the timer / controller and the SCR,

I can happly trace any wires you want if you tell me what to trace, as something doesnt seem right to me, but it could be correct.

here is the wiring between the controller and the thermostat SCR,

Controller end:

SCR Thermostat end:

the wires from 3 and 4 on the controller end are connected to the main live, neutral and earth on the power board

 

[M7R]

oh and now I have fired all the system back up, the SCR wont go into pairing mode, it still has the red "Alarm" LED lit all the time.

and there is no demand for central heating.. ie the timer says it is ON, however the valve keeps the supply to the rads switched off... but if I press over ride then valve moves and the system starts to heat the rads

 

[M7R]

anyone got any ideas? as I would like to get it sorted this weekend if I can, then I can move on the other issue of noisey pump and air in the system

 

[doitmyself]

Questions about white cable marked with a black dot

Does the other end of brown wire connected to terminal 12 go to LR on the boiler?

What are the two ends of the blue wire in this cable connected to?

 

[M7R]

yep the other end connects to LR on the boiler,

and the blue wire is not connected to anything at either end.. the only wire in that cable used is the brown one.

 

[doitmyself]

the SCR wont go into pairing mode, it still has the red "Alarm" LED lit all the time.

Then either the two parts are incompatible (different frequencies) or one part is faulty

if I press over ride then valve moves and the system starts to heat the rads

Presumably you mean the override on the SCR. If so, then the SCR and boiler are correctly wired to the junction box.

Did you purchase a new set - controller and SCR - and did you change both parts?

 

[M7R]

the parts are both from a set, unused before me, both should be the same freqencies

Yes I mean override on the SCR, however if you read the SCR comission guide it states that before a thermostat is paired with the SCR you need to check it is working, this is done by turning the power back on to everything, then once the override button is pressed the boiler should fire... in my case the boiler fires before the over ride is pressed.

I will be chasing the wiring again with my friend who is an electriction on sunday, as when I traced the wiring of everything back something does not seem right somewhere.. the way it is working the SCR is a redundant junction box to some degree.


although I have noticed that inside the stat the sticker says model no: 30002 which is the wired version?! and there is no aerial pic on the lcd display which the instructions say there should be..

I am half tempted to just ditch it and get a new stat and controller:

Siemens RDH10RF/SET-GB Digital Room Thermostat

or

Hortsmann HRT4-ZW Wireless Room Thermostat

any views on these?

 

[doitmyself]

the parts are both from a set, unused before me, both should be the same frequencies

But did they come together in a sealed box?

I have noticed that inside the stat the sticker says model no: 30002 which is the wired version?! and there is no aerial pic on the lcd display which the instructions say there should be

Sound as if you have been sold a pup! Get your money back

I am half tempted to just ditch it and get a new stat and controller

If you are just looking for a wireless thermostat, the Honeywell DT92E is the one to go for.