Best practice for wireless thermostat to combi boiler

[cybergibbons]

I'm just in the process of installing a CM 927 wireless thermostat, which I'm fine with.

I've just had a look at the boiler wiring and it's pretty iffy:
* FCU not screwed to wall, just held by T+E.
* FCU isn't a flex outlet one, and no strain relief on the flex leading to the boiler.
* Chafing of the flex where the boiler panel folds down due to bad routing

I was just going to run a piece of 5-core flex down to the CM 927 receiver and mount it in a surface mount box, so there were two flexes to the boiler, but seeing as I need to replace the mains power flex, I was thinking it would be better to just use one flex.

So the idea is:

* Replace the FCU with a flex outlet one, and screw it to the wall
* Run a single piece of 5-core up to the boiler carrying the power up and the switched stat down.
* Split the L+N for the receiver off the switched side of the FCU
* Mount the receiver in a surface mount box near to the FCU, running another piece of 5 core between them, cable clamped to the wall.

I just want to ask:
1. Is using a single piece of flex for power and control like this OK?
2. Will an FCU clamp take 5-core 0.75mm2 flex?

Thanks.

 

[bhm1712]

its not as if the boiler is going to be moved around, and i would hope that the flex to the boiler was clipped to a wall not just hanging down loose?

if it can be clipped then you dont need strain relief as nothing will ever pull on the cable!

 

[cybergibbons]

It's just hanging loose at the moment, direct into the side of the FCU through a knockout.

 

[PrinceofDarkness]

cyber-g:

1) Yes you can use 5-Core flex to carry the mains and 'stat connections to a combi. It's the neatest way to do it, and certainly my preferred method.

2) Yes, the cable clamp on an FCU will easily accomodate 5-Core O.75mm flex.

Take care to mount the receiver in an 'unobstructed' position, because those units can be a little temperamental otherwise.........



Lucia.

 

[cybergibbons]

Thanks Lucia, great. I'll get that sorted as soon as I get heat resistant 5-core... none of the big DIY chains carry it.

 

[Monkeh]

http://www.tlc-direct.co.uk/Products/CA0dot75HR5.html

 

[cybergibbons]

Cheer Monkeh, it's the impatient side of me that wants to walk into somewhere within a mile of here and pick it up...

 

[ban-all-sheds]

You'll be able to do that tomorrow.