Programmer Horstman to Honeywell ST9400C

[Jbenz]

I'm replacing Programmer Horstman H27XL with a Honeywell ST9400C but having problems with the wiring as the Horstman had 9 connectors and the Honeywell has only 7.

I've attached a photo of the Horstman wiring and a photo of how I've wired in the Honeywell.

I don't think it's heating the water

The central heating works

What have I done wrong?

I have an interconnecting loop over

Thanks

 

[CBW]

Horstman had 9 connectors

Only certain wires used though.

What have I done wrong?

Wired it wrong - you’ve just copied the wiring. Place the grey wire into terminal 3 and remove the loop as it’s not required on the Honeywell

 

[Jbenz]

Thanks Chris,

I did as you said and now I've hot water but no central heating

 

[CBW]

Is the heating still on and thermostat still calling for heat?

 

[EFLImpudence]

You still have the Black in 4 ???

 

[Jbenz]

The heating is still on and calling for heat.

The black wire is still in 4

 

[EFLImpudence]

Mmm. It should be - especially if nothing has changed regarding the black wire.

I can't help but think something else has 'turned off' the heating.

 

[CBW]

Have you disturbed the black wire or has come loose? Photo of changed wiring please

 

[Jbenz]

The black wire is securely in place.

I've just put the wiring back as I had it originally in the photo, and as before, the central heating is working but not the hot water

 

[CBW]

Did you definitely remove the loop?

 

[CBW]

can you post a photo of the new wiring?

 

[Jbenz]

With the wiring as per the attached photo, the hot water heating doesn't work.

The central heating only runs if the hot water is selected to 'OFF'

 

[EFLImpudence]

Place the grey wire into terminal 3

 

[Jbenz]

With the grey wire in 3, only the hot water works

 

[RandomGrinch]

Do you know what type of heating system you have?
Despite the modern wiring, might you have a Gravity system?