Help needed to wire up Boiler thermostat

19
Posted 13th Jan
The other day my Boiler Thermostat (Danfoss RET230P Room Thermostat, 5-30c, 087N743000) stopped working. I could not put the heating on. hot water is fine. when I turn the Danfoss dile i hear a hissing sound so i am guessing it had given up.
No error message on the boiler itself and water lvls are fine. so i decided to buy a new one but the connected are mark different.

does anyone know what wire goes where?
Photos below.

Old thermostat setup
3387841-8O4fc.jpg3387841-FAsaD.jpg
3387841-AJ9Ey.jpg
Set up above shows
Blue = N
Brown/red = L
Brown/yellow = 1
Cross brown cable from L to 3
Yellow and green = nothing connected.
also nothing connected to 2

New Thermostat
3387841-fAPD9.jpg
N = Neutral
N = Neutral
1 = Live
2 = Load

So i am now lost if anyone can help
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19 Comments
Do you have the wiring diagram for the new one?
Your original unit has Live, Neutral and Load. The only extra connection looks like Common, which is simply a link from the Live connection feeding the load with 230v.

On that unit, the Neutral and Live are the connections on the left (brown is Live), whilst the connections on the right will be the Load. The common is the small section of brown wire linking the 2 sides.

The yellow and green wire is earth, which isn’t needed, so it isn’t supposed to be connected, you can tape it up to keep it out of the way.

Here’s the wiring diagram for the old unit for reference...

assets.danfoss.com/documents/DOC224586403659/DOC224586403659.pdf

It’s possible that the new unit doesn’t require the link, but as said, would need to see the wiring diagram / installation instructions to be certain.
Edited by: "Diggsy" 13th Jan
Diggsy13/01/2020 22:54

Do you have the wiring diagram for the new one?


Nope the only thing is the in the box. No diagram.


39669848.jpg




39669848.jpg



So I am guessing it be wired up like

N = Neutral = blue wire
N = Neutral = nothing
1 = Live = brown/red wire
2 = Load = brown/yellow (u cannot see the yellow in the photo)

The earth wire (yellow/green) not needed so can tuck away.
Edited by: "Mackan" 13th Jan
Okay, doing a little googling finally got me enough info, so it appears that the new unit has the connections as you mention...

N - Neutral (blue wire on the original)
1 - Live (brown wire to the left of original)
2 - Load (brown wire to the right of original)

That’s my understanding of it anyway. Seems odd that the new one didn’t come with any diagram
Edited by: "Diggsy" 13th Jan
Just get a spark
ashmac13/01/2020 23:30

Just get a spark


That’s the easiest option if any uncertainty, however this should really be a fairly easy job
Are you saying the new one has 2 Neutrals? Seems odd. I’m not sure I understand that one. Have you a photo of the connections?

Otherwise what you have said connection wise sounds / looks right to me.

Oh but please don’t be guessing!! You need to be sure that the connections are correct!
Edited by: "Diggsy" 13th Jan
Image isn’t working. Edit - is now!

Might be worth posting your question on the Screwfix Community Forum. Lots of tradespersons on there, and I’m sure some will have installed that very thermostat before.
Edited by: "Diggsy" 13th Jan
Diggsy13/01/2020 23:44

Image isn’t working.Might be worth posting your question on the Screwfix C …Image isn’t working.Might be worth posting your question on the Screwfix Community Forum. Lots of tradespersons on there, and I’m sure some will have installed that very thermostat before.


photos shows for me but i have re-added it
39670026-SyS4O.jpg
Link to item screwfix.com/p/flomasta-wired-thermostat/7593g
Link to the manual free-instruction-manuals.com/pdf…pdf
Edited by: "Mackan" 13th Jan
Mackan13/01/2020 23:53

photos shows for me but i have re-added it [Image] Link to item …photos shows for me but i have re-added it [Image] Link to item screwfix.com/p/flomasta-wired-thermostat/7593gLink to the manual http://www.free-instruction-manuals.com/pdf/pa_1004684.pdf


That manual is useless! No mention of the wiring at all. The 2 N’s is throwing me a curveball, can’t get my head around that at all. Would definitely suggest a post on Screwfix Community.
Diggsy13/01/2020 23:56

That manual is useless! No mention of the wiring at all. The 2 N’s is t …That manual is useless! No mention of the wiring at all. The 2 N’s is throwing me a curveball, can’t get my head around that at all. Would definitely suggest a post on Screwfix Community.


I am guessing that is something i will have to do, just did not want to have to register for it.

i thought i got it working when i done
N = Neutral = blue wire
N = Neutral = nothing
1 = Live = brown/red wire
2 = Load = brown/yellow (u cannot see the yellow in the photo)
this was not fixed correct and the wires where just hang on the outside but when i put them in the correct way(so i can put it on the wall) it seem to not work. (i may not of gave it enuff time). but i need to get a new fuse before i can try again as i blow a 2amp fuse. the boiler said it can take up to 3 amp fuse and i only had a 1 amp fuse to still have hot water atlest
Edited by: "Mackan" 14th Jan
Did it work before you tried to fix it in position? If so and fixing it blew a fuse it’s likely that wires have touched on doing so, but rather than take any chances just register and get an answer from a tradesman
Blue into neutr
Leave the 2nd neutral empty
Brown in live in first pic into 1
Brown 1 in pic 1 into number 2.

Don't worry if you mix up 1 and 2 as you can switch them back over as they are both live connection from the same circuit.

N is neutral
1 is permanent live
2 is switched live.. live sent from the permanent live to the boiler when the thermostat temp reaches below set temperature.
Edited by: "kash2013" 14th Jan
Mackan14/01/2020 00:04

I am guessing that is something i will have to do, just did not want to …I am guessing that is something i will have to do, just did not want to have to register for it. I thought I got it working when i done N = Neutral = blue wire N = Neutral = nothing 1 = Live = brown/red wire2 = Load = brown/yellow (u cannot see the yellow in the photo) this was not fixed correct and the wires where just hang on the outside but when I put them in the correct way (so I can put it on the wall) it seem to not work. (I may not of gave it enuff time). but I need to get a new fuse before I can try again as I blow a 2amp fuse. the boiler said it can take up to 3 amp fuse and I only had a 1 amp fuse to still have hot water atlest


That looks the right order for the connections. Make sure the earth wire is sleeved and tucked out the way if there's no terminal for it.

1A and 2A are unusual fuse sizes. 3A is a common size and usually used for boilers.

The two neutral terminals are probably connected together. It may be to allow a live & neutral in from the supply, then switched live & neutral out to the heater. Just ignore the spare neutral terminal.
Doug_14/01/2020 01:06

That looks the right order for the connections. Make sure the earth wire …That looks the right order for the connections. Make sure the earth wire is sleeved and tucked out the way if there's no terminal for it. 1A and 2A are unusual fuse sizes. 3A is a common size and usually used for boilers. The two neutral terminals are probably connected together. It may be to allow a live & neutral in from the supply, then switched live & neutral out to the heater. Just ignore the spare neutral terminal.


The wires inside the boiler have 2 amp or so the diagram says and it said can take 3amp. The power socket it connects to is running a 3 amp fuse switch.
I am going to be picking up some fuses today as the one in the boiler seems to be mini fuses compare to ones you find in UK plugs and so on.
Edited by: "Mackan" 14th Jan
So picked up fuses 2 amp and 2.5 amp (they did not have 3 amp). will give it another go tonight. I am going to keep it at 2 amp at the moment and will keep the 2.5 for backup in-case the 2 is not big enufff for the new thermostat. i think the thermostat need very little power to start with but i may be wrong. finger crossed it works tonight as getting pretty cold in the house.

I am going to get a guy out to service and fix a very small leak on the boiler as it is now 6 years old. last service was 5 years ago.
Just an update 20mins later it is now working again

Wires where
N = Neutral = blue wire
N = Neutral = nothing
1 = Live = brown/red wire
2 = Load = brown/yellow (u cannot see the yellow in the photo)
Mans works find on 2amps inside the boiler and 3 amp outside feeding the boiler
Mackan14/01/2020 18:42

Just an update 20mins later it is now working again Wires where N = …Just an update 20mins later it is now working again Wires where N = Neutral = blue wireN = Neutral = nothing1 = Live = brown/red wire2 = Load = brown/yellow (u cannot see the yellow in the photo) Mans works find on 2amps inside the boiler and 3 amp outside feeding the boiler


Good work! Seems that the wiring was pretty much as we thought all along. It was just the 2 neutrals that threw me.

The fuses are just to protect the thermostat from damage if there are any issues with the power. Whilst a 3 amp would be better, the 2 amp will function perfectly well, it would just blow easier than the 3 amp.
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