Thermostat Replacement

Postby Mike Dybacz » Mon Feb 11, 2008 12:29 pm

I have a combi boiler which used a Honeywell rotary thermostat. I have just replaced the thermostat, as its broke, with a digital Sunvic TLX 7501. The Honeywell had 5 connections but used only 3 i.e. 1 3 and 4 and the TLX 7501 has 3 connections 1 2 3. I have got the thermostat working i.e. switching the central heating on, by connecting 1 to 3 and 3 to 2 but it does not seem to switch off when the correct temperature is reached.
Anyone got any idea as to why ?
Mike Dybacz
Rank: Labourer
Progress to next rank:
Posts: 1
Joined: Mon Feb 11, 2008 12:08 pm


Simply Build It

Postby ericmark » Mon Feb 11, 2008 4:34 pm

In general old thermostats had live in, live out, neutral, and earth. The new ones run on battery and are double insulated so only have live in and live out. But also may have normally open contact as well as normally closed. The normally open will not normally be used. There are normally instructions saying which is which with each unit. Often there is a delay built in.

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