FHT floor heating control - mystery wiring diagram!!

D4dog · 1 Jun 2008

I am just fitting under-floor heating, and I have up against a problem in wirig in the thermostat/timer. It was purchased from Screwfix, but is from a Dutch company, and is labelled "FHT-Control".

The problem is the wiring diagram. The sensor links are clear, as are the earths. However, it has 4 other terminals. 1 has an arrow pointing upward. 2 is clearly marked "N". 3 has an arrow pointing downward. 4 has another arrow pointing upward. Terminals 1 and 4 then have the words "heating", and appear linked in the wiring diagram. My options appear to be:
Terminal 1 is the incoming live, with 3 and 4 representing the heating element connections.
Terminal 3 is the incoming live, with terminals 1 and 4 connected to the heating element.
This is the worst set oif installation instructions I have ever seen - anyone any ideas which is correct?

Cheers

D4.

Steve · 1 Jun 2008

Can you scan or take a photo of the wiring diagram? Or find a link to it online.

Steve · 1 Jun 2008

I found the instructions on the screwfix website, as you describe.

http://www.screwfix.com/sfd/i/cat/pdfs/68/p3987468.pdf

Connect the heating element to 1 and 4.

N to 2, L to 3.

Of course, as 3 isn't labelled very well, it would be wise to contact the manufacturer (there should be a phone no) and ask their advice before shoving 230 volts up the wrong terminal and ruining your controller.

They aren't bad instructions, just this one small thing.

Mud Hut · 1 Jun 2008

You could also try switching on and off the heating output and use a continuity meter to determine which 2 of the terminals are the relay contact. Typically the heating output is a volt-free contact to which you have to put 240V to one end, then one end of the heater element to the other, and the other end of the element to neutral.

Also, as there a 4 terminals, one might be permanently live so be careful!

333rocky333 · 1 Jun 2008

I would try the manufacturers website , it may be foreign ,but the wiring diagrams may be clearer.

Mud Hut · 1 Jun 2008

This manual may also help. This one is different as you don't have to make your own link from L to the relay contact - it looks as though it has been done for you internally.

http://www.enerfoil.com/me-thermostat/install.htm

Strongly recommend contacting the manufacturer unless you are competent enough to connect it up and test it yourself.

D4dog · 1 Jun 2008

Went with what seemed logical - the diagram attempts to show heating load (I think) on terminals 1 and 4. So made 3 live, and all works. The manufacturers web-site is next to useless - the only diagram they have is the same.

But if anyone else comes across these (used for Kilma heating mats from Scewfix), heating element should go to 1 and 4, live supply to three!

Thanks for all the advice, guys.

Guinea · 18 Oct 2010

Mine was fitted years ago but haven't connected it yet. RCD on the feed which folloing your advice will connect live to 3!
The external sensor is a twin cable (brown/white). Does it matter which is connected to 7 & 8 - I assume not as it is either on or off presuamably, bt thought I'd check.

cheers.

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FHT floor heating control - mystery wiring diagram!!

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