DIY Doctor

OTN-1991 Thermostat

Postby kwiseman » Sun Mar 01, 2009 10:22 pm

Hope someone can help. I have had to buy a new thermostat for my underfloor heating but can't remember which wires went where.

I have a L and N from the mains
From the underfloor heating, I have one cable with a blue and green/yellow(I persuming is Earth but there is nothing on the instatlation diagram showing where earth would go) and another cable with Brown and again the persummed earth.

The diagram on the instatlation is not clear. The manual so you can see connections can be found if you Google "" and then view the pdf area for "otn-1991 manual.pdf"

Hope someone can help urgently.

Rank: Labourer
Progress to next rank:
Posts: 1
Joined: Sun Mar 01, 2009 10:16 pm


Simply Build It

Postby sparx » Wed Mar 04, 2009 9:23 pm

looking at drawing then line into term 1, Neutral in 2, heating mat brown & blue into 3 & 4 respectively, sensor wires go to 6&7 term 5 is for timer input if used or linked to term 1 if no time switch fitted.
earth screen of mats cables must link to mains earth in term block possily in back of stat.
screens MUST be earthed and circuit MUST be RCD protected,
regards SPARX
Rank: Project Manager
Posts: 2166
Joined: Wed Mar 21, 2007 8:33 pm
Location: The fifth continent.

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics