Central Heating timer replacement

[canarydan]

Hi,

I have a boiler running the central heating only and I think the timer switch is broken as it keeps resetting.

The current timer is a Randall E1 (think its quite old) and the heating electrics are a little over complicated.

The E1 has 5 wires to it into: L,N,1,2,3.
1=n/o (i think)
2=comm
3=n/c

I want to replace it and am thinking a Horstman C17 but need help on which wires go to which terminals (C17 has L,N 1,2,3,4)

My set up is a bit strange as it has a frost stat (yes.. inside the house) as well as a room stat, Plus wires in from the bolier and pump
Currently I think one of the frosts stat wires goes into the E1, also one of the room stat wires goes into the E1. (can't remember where the other going into the E1 is from - as i am writing this from work!)

Total wires into the junction box:
Frost stat (blue,brown,earth)
room stat (yellow,red, blue, earth)
bolier/pump (earth, 2 black, 1 brown, 1 blue)
power in (E,L,N)

can anyone help?

 

[ELZ4742]

is it a y plan or an s plan? (1 valve or 2)

 

[ELZ4742]

if its a y plan (1x 3 port valve)this may help

http://i26.photobucket.com/albums/c130/jimjohn2/threeportwiring.swf

 

[canarydan]

...I have no idea I am afraid - I am no expert.
Was just hoping to be able to swap over the existing connections..

what is the difference?

 

[Taylortwocities]

The Horstmann replacement programmers come with a handy table that lists most old programmers and tells u which wires go where.

If you look up the Horstmann site u can download the document.

TTC

 

[333rocky333]

if its a y plan (1x 3 port valve)this may help

http://i26.photobucket.com/albums/c130/jimjohn2/threeportwiring.swf[/QUOTE]

Does one of these exist for an s plan
Thanks

 

[Adam_151]

Diagrams for C, S, S plus, W, and Y can be found here: http://content.honeywell.com/uk/homes/systems.htm

 

[Taylortwocities]

I did suggest that you look at the Horstmann site.
I have now had to do this for you

It says in the replacement guide that the recommended replacement for the Randall SET E1 is the ChannelPlus H11.
It also says that with the H11 all you need to do is to replace the backplate and that the terminal connections remain the same.

See page 4 here http://www.horstmann.co.uk/downloads/ElectronicDocuments/Central-Heating/WiringGuide.pdf

I suggest you do that rather than trying to rewire your whole system.