how to wire a heatmiser wireless reciever to wocester bosch?

[lechat]

Hi - please help!

I have a Worcester Bosch Greenstar 25/30si. It currently has a MT10 manual timer on it but the timer dial is broken so I have to switch it on and off. I decided to replace the timer with a Heatmiser wireless programmable thermostat.

Problem is I don't know how to wire it up. The two diagrams for each product seem to say opposite things? See attached:

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• lechat
• 10 Jan 2012
• 2

Questions:

Do I have to remove the cable which currently goes from the FCU to the boiler, and run it from FCU to the receiver instead, and then put a new one on from the receiver to the boiler (as per Heatmiser diagram) or do I just leave the mains supply on the boiler and just connect the receiver to the boiler (as per boiler diagram)?

Which terminals on the boiler do I need to connect to which on the receiver? (eg on heatmiser diagram there are 2 terminals to connect, but on boiler diagram there are 3)

What cable should I connect with 0.75mms 3 core?

Also, what do I do with the existing timer that is attached to the boiler - do I need to remove it and will that break a circuit somewhere?

Many thanks in advance for your help.[/img]

 

[stem]

As you have also posted this in the electrics forum I have posted a reply for you there. Be careful! the mods will be after you for duplicating a post, if you get two separate threads running on the same topic, it can get very confusing.

 

[lechat]

its cos i posted it in plumbing but the picture didnt show properly and the forum said i wasnt allowed to update it, so i posted a new one in electrics. turns out i could have updated the picture - newbie error! ill delete one now if i can!

 

[lechat]

Hi stem,

All good then - you're right - i had no thermostat before - just the timer. So i'll remove link and wire as previously mentioned in your email.

Many thanks for all your help.

(apologies to moderator too!)

 

[stem]

With the wiring diagram shown earlier, which was based on the receiver wiring diagram you posted showing 4 wires, there are actually two cables for the same thing. Ls to A1 is a permanent live supply the same as L to L. I kept to this format to keep it simple. However, from your previous comments I think you will understand the alternative diagram below. I have checked the Greenstar manual and as you rightly state, a three wire solution is possible, by removing one of the aforementioned duplicated wires and replacing it with a link between A1 & L at the receiver. I have also used the Ns terminal for the neutral supply to the receiver as it may be easier than getting two wires into the N terminal. The original diagram is still ok, both will work.

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• stem
• 10 Jan 2012
• 1