Is this a room stat?

[mport343]

Hi,
I dont know if i'm being a bit thick but hopefully someone can answer this 1 for me. The firm i work for are doing a refurb on part of a school building and during the removal of all the old cable we removed what we took to be a standard room stat (very old,sandvik,gold coloured) which is to be replaced by a new 1, it had a 1.5 3core flat grey (old colours) at it and because of the distance/route the cable travels back to the boiler house it originates from,the decision was made to re-use it in the new stat,we've now got to the stage where we switched the heating back on and we've found that when the system is running the red is live,yellow and blue are dead,when the heating switches off the blue is live and yellow and red are dead. Ive never come across this before and am hoping someone may have more knowledge on this, thanks.

 

[mark ju]

had something similiar a few years back on a new build that one of the lads ballsed up. turned out it was switching neutral and the neutral connection in the stat was fed live. might be worth a look!!!

 

[mport343]

thx for the reply, as far as we know the system worked properly before, we just need to replace the old equipment with a newer version, made more difficult now coz the old one got thrown out with the rubbish!

 

[telectrix]

it should be red=Lin, yellow=Lout,blue=N. you'll have to check the cable at the boiler end.