Potterton EP2000 to Honeywell CMT927

[hus882]

All,

I was hoping you could help me, we are trying to replace a cabled Stat with a wireless CMT927 and we are having difficulties! I was wondering if anyone could give me some advice as to how to cable up the two units, we have taken power from the EP2000 down to the RF receiver, originally the cables from the stat were going into:

Blue - 4
Yellow - C
Red - 2

The cabling appears to be quite a mess, to my understanding (apologies its quite limited) the its pumped heating system with gravity hot water, currently its working along side a netaheat boiler. I will add a pic later, what i need to understand is how many cables are required from the CMT927 and where they need to go?

Your help is much appreciated - I will be online later to add some additional information and pictures.

Thanks,
Hus

 

[dontknowitall]

I'm sure others will correct me if I'm wrong but I think you pick up the live from the heating circuit and the neutral is connected to the boiler.

So with the above if all 3 wires go to the junction box, then pick up the live and neutral and leave the other disconnected.

The Honeywelluk website has loads of info.

 

[hus882]

I'm sure others will correct me if I'm wrong but I think you pick up the live from the heating circuit and the neutral is connected to the boiler.

So with the above if all 3 wires go to the junction box, then pick up the live and neutral and leave the other disconnected.

The Honeywelluk website has loads of info.

Thankyou for your response, I am sorry not to clear on what you mean, I had thought that when connecting the CMT927 to the EP2000 you effectively ceded control of the Central Heating to the CMT927, post install the CH is set to always on with the trigger coming from the wireless receiver. I have attached a pic of spaghetti junction!!

 

[dontknowitall]

Ah! I see what you mean. I'd go for an easier option and replace the EP2000 with the Honeywell set up.

 

[hus882]

Ah! I see what you mean. I'd go for an easier option and replace the EP2000 with the Honeywell set up.

I have actually picked up a Honeywell ST9400C (iirc) to replace the EP2000 but its such a mess that neither I or my handyman know where to start! I think i would settle on getting the wireless stat working and then tackling the bigger issue next year. I have updated the first post as I realised i got my cabling wrong, the original stat was actually cabled in as per the below:

Blue - 4
Yellow - C
Red - 2

If the cabled stat had three cables, shouldnt i also wire in three from the CMT927, it has A B C but its not clear what there for.

 

[dontknowitall]

I'm tempted to advise you to ask a heating engineer in as he will sort this for you.

Alternatively you might want to undo all those wires, fit a Honeywell junction box (with the labels) then identify which cable does what and wire up the junction box. The wiring in your photo is acting as the junction box and the programmer.

 

[Puddle]

From wiring looks like you have a actuator valve on system that requires satisfied switch from room thermostat

so you have connected l/n

then connect
terminal 4 to A ......... live in
terminal c to B ......... l when calling
terminal 2 to c ......... l when satisfied

 

[hus882]

Thanks chaps - will try it out and report back

 

[hus882]

From wiring looks like you have a actuator valve on system that requires satisfied switch from room thermostat

so you have connected l/n

then connect
terminal 4 to A ......... live in
terminal c to B ......... l when calling
terminal 2 to c ......... l when satisfied

Cabled it in as per the above and it worked! Thanks to both of you for your help and advice, I will arrange an engineer to sort out spaghetti junction in the new year

 

[marleyco]

I realise you have a new programmer, but thought I might add, I ordered a ep2000 today for 46 plus vat from plumbcenter, will be here tomorrow. so if all else fails!