central heating programmer

[stormin7315]

Hi
I have just purchased a new Horstmann H27XL programmer,but on opening
discovered that it has 9 terminals and that includes the earth,but on my salus
EP200 there is only 7 pins earth included.Is it possible to wire this new programmer in or is this a non starter.My system is fully pumped with 2 2-port zone valves and cylinder stat.Boiler is a Worcester condensing unit?I did connect the new programmer up and the display did light up but i could not get the heating to switch on.The salus programmer is wired with 2 wires to neutral,2 wires to live terminal and terminals 3 and 4 each have a single wire going to them.1 and 2 terminals are not connected.Reason for changing is that the salus is a pain to programme.

 

[ban-all-sheds]

Have you compared the wiring diagrams for the two?

 

[stem]

Yes you can swap them. The Horstmann has extra terminals for linking the live supply, which the Salus does internally. The wires will need to be swapped over as below. As you have two, 2-port valves, it is normal not to have wires connected to the hot water off or central heating off terminals, so they can be ignored.

Salus (N) connect to H27 (N)
Salus (L) connect to H27 (L)
Salus (1) connect to H27 (3) This is hot water off connection (if used)
Salus (2) connect to H27 (6) This is central heating off connection (if used)
Salus (3) connect to H27 (1) This is hot water on connection
Salus (4) connect to H27 (4) This is central heating on connection

You will also need to add a link between terminals (L) (2) & (5) on the H27 This is shown as the dotted lines in the Horstmann manual.

You can find the manuals with the wiring details here
Horstmann H27XL
Salus EP200

 

[stormin7315]

Hi again
I have now managed to get the boiler to fire up,but have now discovered another problem.The heating pump does not overrun when the boiler closes down,and as a result there is all sorts of banging coming from the boiler when it shuts down.On investigating wiring in boiler the live lead for the pump has been connected but not the neutral lead.It has had a terminal block fitted on to it and is just hanging inside boiler casing.Any idea what that would be about.
BTW thanks very much for your replies to my previous question.

 

[stem]

Assuming that the pump runs at some point, then it would appear that it gets a neutral from somewhere. Sometimes the neutral used by the motorised valves is picked up from a wiring centre and used for the pump connection. But pump control shouldn't have changed with just a programmer swap. Did it work before? has something else been changed?