2 port added to y plan

[Martin Atkins]

Hi
Plumber has asked me to wire in a Honeywell wireless stat and a new 2 port valve controlling separate radiator in conservatory into a y plan system
wired it all up as a separate entity with the orange of the 2 port in with the Orange of the 3 port and the cylinder stat,works fine if turned on its own but when the existing heating or hot water is on it will trip when the 3 port opens
I should add that I have taken a supply for the new 2 port from an unused fused spur in tank cupboard as the existing wiring centre has no permanent live
I'm back there tomorrow afternoon so any help would be great

 

[Leesparkykent]

What trips the RCD or mcb? Any additions should be wired to the same supply as the existing controls (load side of existing FCU). How is the new two port plumbed in? As when the conservatory thermostat is calling and turns on the boiler/pump it will also pump round the open side of the 3port.

 

[davesparks]

What you have done is dangerous and fundamentally wrong. You must not feed a circuit from two seperate ocpds. The whole boiler control circuit must be fed from the one supply, or else you need to fit relays to keep the supplies electrically seperate.

 

[telectrix]

agree with last 2 posts. might even be that the 2 circuits have their neutrals in separate N bars, causing trip when load is applied.

 

[Martin Atkins]

I understand that it is wrong, the supply is in kitchen with programmer and boiler I'm in the tank cupboard with a wiring centre of sorts the old wiring has no permanent supply to the cupboard if I can get a supply from boiler I will but why is it tripping the red

 

[Leesparkykent]

I understand that it is wrong, the supply is in kitchen with programmer and boiler I'm in the tank cupboard with a wiring centre of sorts the old wiring has no permanent supply to the cupboard if I can get a supply from boiler I will but why is it tripping the red

Rewire it so it picks it feed up from the programmer/boiler.

 

[Guest77]

I understand that it is wrong, the supply is in kitchen with programmer and boiler I'm in the tank cupboard with a wiring centre of sorts the old wiring has no permanent supply to the cupboard if I can get a supply from boiler I will but why is it tripping the red

Then why on earth do it, Dave is right, you need to sort that out for sure, have you parallelled up the neutrals between the 2 valves? and where did you connect the brown of the 2 port to? it should be part of the central heating system, surely it should be to the central heating supply from the clock not a completely different circuit???

 

[Lucien Nunes]

why is it tripping the red

Probably because the RCD protects only one of the two circuits, and your rogue interconnection is taking current from one and returning it to the other. This is highly dangerous. Someone might want to work on a socket outlet fed from the RCD, so he DP isolates it at the RCD, locks it out and and checks it's dead. Some time later the room cools, your stat closes, backfeeds the RCD-controlled circuits from the other supply and gives the poor sparky a belt or worse. Not good!

 

[Martin Atkins]

Ok guys thanks for the replys duly noted will return tomorrow and put it right

 

[Leesparkykent]

If you can't get a cable to boiler/FCU/programmer position without major disruption then a possibility might be to use a relay to control the hot water off and use the core in the programmer that is connected to HW off atm as a permanent feed to wiring centre.

 

[davesparks]

It still won't work though as the 3 port will always be open to at least one port, so when this 2 port is calling it will also be heating another circuit (this usually manifests itself as scalding hot water.

So the OP has installed a borrowed neutral fault which presents a risk of electric shock to anyone working on the system and put the homeowner at risk of severe scalding from overheated hot water.

Who says this trade has gone to the dogs?

 

[telectrix]

It still won't work though as the 3 port will always be open to at least one port, so when this 2 port is calling it will also be heating another circuit (this usually manifests itself as scalding hot water.

So the OP has installed a borrowed neutral fault which presents a risk of electric shock to anyone working on the system and put the homeowner at risk of severe scalding from overheated hot water.

Who says this trade has gone to the dogs?

to be fair, though, OP has admitted his mistake and is going back to rectify it.

 

[Martin Atkins]

Davesparks while I appreciate your input
how do you know that I have left it with a fault over the weekend I actually realised this is not right and have dissconnected everything I did on Friday to leave it as I found it and was looking for ideas

 

[Leesparkykent]

It still won't work though as the 3 port will always be open to at least one port, so when this 2 port is calling it will also be heating another circuit (this usually manifests itself as scalding hot water.

So the OP has installed a borrowed neutral fault which presents a risk of electric shock to anyone working on the system and put the homeowner at risk of severe scalding from overheated hot water.

Who says this trade has gone to the dogs?

i did point this out in post two.