Replacing a room stat

[orbital]

Hi I want to replace an old Honeywell room stat with a

Horstmann Centaursaur 7 programmable stat

http://www.horstmann.co.uk/downloads/ElectronicDocuments/ThermoStats/CentaurStat1-InstallationInstructionsMk2.PDF

The Honeywell stat was wired thus.....

Blue went to 2

Y went to 3

and red to 1

I presume that red will now go to 1

Yellow will now go to 2

Blue will go to 4 (Parked) I guess this means its not used just a place to put the not needed neutral.

 

[sparkytim]

Correct this unit does not require the nuetral as did the former

 

[mikep]

Just to say that some Stats do need a neutral as it feeds a small heating coil below the bi metal bar which convects heat up through the stat giving an airflow through it that is combined with the ambient temperature of the room, I can't remember what they call the heater element I think it's called an exciter, as for the Centaurstat Tim's right does not need the neutral.

Mike.

 

[ProDave]

I can't remember what they call the heater element I think it's called an exciter, as for the Centaurstat Tim's right does not need the neutral.Mike.

I think it's called a booster, or accelerator.

Basically with the mechanical bi-metalic thermostats, the small amount of heat generated when the thermostat is closed, reduces the hysterises. Without it, there would be a difference of several degrees between the turn on, and turn off temperature.

Electronic thermostats don't need the boost heater so often don't need a neutral connection.

 

[mikep]

Well Prodave only seems like me and you on this one. but we're both on the money anyway.

Mike.