Changing old honeywell rooms stat

[rantoftheday]

replacing old honeywell room stat to a new white one

three wires at honeywell(not incl earth which is to back box)

wires are red blue and yellow

red was in terminal 1, blue in 2 and yellow in 3

on putting these cables in the same numbered terminals on the new room stat the rcd is tripping

any ideas what terminals the cables should go in?

 

[Short Circuit]

It doesnt always work that the terminal numbers are the same. Its likely that the red is the live, the blue the neutral and the yellow the switched live (return). What is the details of the new stat?

 

[TaffyDuck]

permanent live 1, break on rise 3 , neutral 2 dont need this unless you need the call light to come on

 

[oldtimer]

permanent live 1, break on rise 3 , neutral 2 dont need this unless you need the call light to come on

EHHHH Taffy me thinks you got the neutral not needed bit wrong You do indeed need a neutral at a room thermostat if you dont then your energy bill will be 8-10% dearer why do you ask well here is a bit of history for you when energy was cheap nobody bothered and the spark would wire the room stat as a switch ie a T&E instead of a 3 core and earth.

So how does it work well there is a thing called a anticipator or accelerator resistor fitted to the bi-metal strip that only comes in to play when there is a call for heat as the resistor heats up and it is this that cuts down the thermostat switching differential or in other words gives it a finer control ie set for 20oC switches on at 19oC switches off at 21oC but without it it may switch on at 17.5oC and off at 22.5oC

So alway but alaways connect the neutral on a wall thermostat if it has one especially in this climate Also my thermostat has Red switched live from the time clock Blue is the neutral and yellow is the call for heat.

 

[Megavolt]

What is the make and model of the new room thermostat

 

[TaffyDuck]

Old timer, as always I`m open to suggestions. Wouldn`t that system however result in more switching on/off of the boiler as the differential is smaller, the start up being the most inefficient phase of the boiler cycle?

 

[Short Circuit]

i have to say, i was always told to connect the neutral at the stat, and most of the older styles needed it! I fit the digital stat / room programmers now and they need the neutral too!

OP - we need the details of the new stat!

 

[rantoftheday]

thanks for all advice guys it was a tower stat and the red was the feed from the clock, the yellow the switchwire and blue the neutral managed to figure this out with my meter checking the continuity as i turned the temp wheel to see which terminals were switching thanks guys

 

[Guitarist]

I am somewhat concerned that you would just terminate the cables as they were before, without even checking that you were wiring it correctly. Good job we have RCD's these days.

 

[rantoftheday]

Go strum yourself

 

[Guitarist]

I merely expressed concern that with something as dangerous as electricity you would "assume" the wiring would be the same and hope for the best. If you want to insult me for that, then fine.

 

[oldtimer]

Old timer, as always I`m open to suggestions. Wouldn`t that system however result in more switching on/off of the boiler as the differential is smaller, the start up being the most inefficient phase of the boiler cycle?

Well thats one way to put it but look at it this way you could ditch the neutral and the average heating bill of £900 just got £90 dearer