Replacing a Honeywell t40 thermostat

[wayne_crowther]

I am replacing a Honeywell T40 room thermostat witha Drayton Digistat 3. The T40 has 4 wires ( earth not required for the Digistat) The live on the T40 is in terminal 1, the neutral to terminal 2 and the switched live to terminal 3.

On the digistat instructions it state that common should be to terminal 1, demand to terminal 3 and satisfied to terminal 2. Can anyone advise which wire should go to which?

 

[Steve]

same as the old one, as far as i can tell! (t1 is permenant live, t2 is switched live, t3 is neutral) sure someone else will confirm!

 

[baldelectrician]

I CAN'T BELEIVE SOMEONE TOLD YOU TO CONNECT THE NEUTRAL

DO NOT DO IT

SLEEVE OR CONNECTOR BLOCK THE NEUTRAL AS IT IS NOT USED

LIVE TO C TERMINAL

SWITCHED LIVE TO 3 TERMINAL

 

[Lectrician]

same as the old one, as far as i can tell! (t1 is permenant live, t2 is switched live, t3 is neutral) sure someone else will confirm!

kerboom!

 

[breezer]

I hate to say this, but some stats do require a neutral as well as live, its to operate a resistor which acts as a tiny heater to "correct" the stat.

the other thing is it may be the poster thinks the black is neutral and it may be switched live.

just a thought

 

[Big_Spark]

Breezer, these are battery powered Digital stats and they act purely as switches. They do not require the connection of a Neutral..infact, as has been pointed out, connecting a neutral would introduce a dead short and a big bang and a frazzled stat would result...

 

[breezer]

True, but he also said

I am replacing a Honeywell T40 room thermostat ......... The T40 has 4 wires

Live, neutral, switched live, and earth?

still i suppose the best advice would be to compare what did what on the old one to what does what on the new one, and which colour does what

out of interest, the Honeywell t40 thermostat does not seem to exist, not saying it doesnt exist, only seems not to. I did a quick google for it, and this thread is the one page to come up, there was also a mention on the screwfix forum that the stat doesnt exist, and i could not find any real refernce to it, so that makes me think it must be very old, in which case it probably does require a neutral.

 

[wayne_crowther]

Thnaks baldelectrician and bigspark - wired as sugested and you were spot on. Many thanks

Wayne

 

[Beanzy]

Just out of interest Breezer & Crafty..... if Wayne had followed your incorrect advice would you have bought him a new 'stat?

 

[breezer]

Just out of interest Breezer & Crafty..... if Wayne had followed your incorrect advice would you have bought him a new 'stat?

my advice was not incorrect.

i pointed out the best way to do it was to look and comapare one with the other (see what colour does what, and where it is connected on the old one), also i said older stats had a neutral, no where did i say how to wire it, so before you accuse me of anything please get your facts RIGHT!

 

[Lectrician]

Weather or not wayne told us the correct model number, he told us what the trminals do in his first post.

I assume he found this info from the stat cover or install instructions. He clearly tells us which are com, sat, demand. No mention of neutral. Crafdety guesed that term 3 be a neutral, which is actually the demand terminal.

As I said......kerboom!

 

[breezer]

Beanzy, show me where i said how to wire that stat then.

you wont find it becuse that is NOT what i said.

I did say

still i suppose the best advice would be to compare what did what on the old one to what does what on the new one, and which colour does what

 

[Beanzy]

Here you go breezer. surprised you neede me to find your quote.

and i could not find any real refernce to it, so that makes me think it must be very old, in which case it probably does require a neutral.

 

[breezer]

you missed the point, no where did i say HOW to wire it though did i!

as i also said for the 3rd time, the best thing to do is compare how the old one is and compare it to the new one. so you are still wrong

 

[Lectrician]

Would have still gone bang