Switchmaster 900 replacement

[TheBigAitch]

Hi Guys,

Hope you can help, i found one or two other threads about this but not quite like ours...

Ours is wired - N, L, Heating On, HW On, HW Off. (no wire in heating off)

Can anyone recommend a replacement programmer that doesn't require a heating off connection?

Many thanks

 

[Boilerman2]

Honeywell ST9400C is a 7day 3on/off per day programmer
that will be a straigt swap (after fitting the new wiring plate

L - L
N - N
HW On - 3
CH On - 4

 

[TheBigAitch]

hi boilerman2

thanks very much for your speedy reply, please excuse my ignorance but will the hot water be ok without the off wire then?

thanks again

 

[Boilerman2]

Yes just as your old switchmaster was fine without HW off connected
remember these terminals are OUTPUTS not INPUTS so it will be fine

 

[gaswizzard]

The honeywell ST9400C being a 7 day programmer (5/2) , I take it you have a Y plan so terminal 1 will switch HWoff with 3 and 4 being HW/CH on , terminal 2 is CH off which you won't use.

 

[doitall]

Think boilerman is getting confused.

The hw off needs to be connected to terminal 1

 

[TheBigAitch]

argh! OK, right getting confused now! lol


SO - are you guys basically saying that I can just substitute the connections across exactly like the old one and leave 'heating off' empty as it already is?


(I think the main thing that's confused things is boilerman2 referring to hw off when i think he meant heating off?)

 

[doitall]

You don't need the htg off terminal the rest is the same.

 

[Boilerman2]

Whoops! misread original post

try this

L - L
N - N
HW OFF - 1
HW ON - 3
CH ON - 4

My sincere apologies

 

[picasso]

You changed that quick

 

[Boilerman2]

 

[TheBigAitch]

thanks for your replies everyone