Help required in wiring of a new digital Central heating timer control

[SIMON BOWDITCH]

Can anyone Please help!!!

I have a really old Baxi back boiler with a Horstmann Coral dial timer that has stopped working and need to replace with a new digital one. Did some research online and saw that it could be replaced with a Sunvic Sunpro2000 which i have now purchased but am a bit confused as to which wire need to go where as the old Coral has 8 wiring terminals (2 are empty) and the new one only 6.

There are 5 wires going into the old timer from various parts of the system as listed below:

A. MAINS WIRE (2 CORE RED/BLACK)

B. CENTRAL HEATING PUMP (3 CORE BLACK/RED/NEUTRAL)

C. HONEYWELL CH VALVE (3 CORE BLUE/BROWN/NEUTRAL)

D.HOT WATER PUMP (3 CORE BLUE/BROWN/NEUTRAL)

E. CABLE GOING TO BACK BOILER (4 CORE BLUE/BROWN/BLACK/NEUTRAL)


The Coral has 8 terminals numbered 1 to 8 and the wires listed above go to the following terminals:

1.RED MAINS (A) / BROWN BACK BOILER (E)

2.BLACK MAINS (A) / BLUE HW PUMP (D)

3.BLUE HONEYWELL (C) / BLACK CH PUMP (B) / BLUE BACK BOILER (E)

4.BROWN HONEYWELL (C) / RED CH PUMP (B)

5. EMPTY

6.EMPTY

7.BROWN HW PUMP (D)

8.BLACK BACK BOLIER (E)

(7 & 8 ALSO HAVE A SMALL RED BRIDGE CABLE LINKING THEM)


The new Sunpro 2000 has 6 terminals as shown below :

LIVE, NEUTRAL, 1-HW OFF, 2-CH OFF, 3-HW ON, 4-CH ON


SO CAN SOMEONE PLEASE GIVE ADVISE WHICH CABLES NEED TO GO WHERE ON THE NEW TERMINAL

 

[ianmcd]

post a pic of your existing backplate wiring, you could have used any 2 channel timer didnt have to be the sunpro, wire colours mean absolutely nothing in a heating circuit, do you have zone or mid position valves ? your post infers that you have 2 x pumps one for HW and one for heating, will be extremely unusual if you do

 

[SIMON BOWDITCH]

The system is about 40 years old but works like a trojan horse !!!, i know its not energy efficient but until it goes to boiler heaven quite happy with it, as i am not a boiler engineer not sure if i have zone or mid position valves ?
With regards to the pumps i defo have 2 the older blue one works with the hot water (when turned on you can hear it slightly and feel the vibration in the pipe going to the tank) and the newer red one next to the valve is dormant unless heating is asked for. I have taken some pictures and attached

 

[ianmcd]

That looks like a complete bodge, the square silver box to the right hand side of the red pump is a zone valve, it looks like it has been fitted to close when you only want HW running and not CH to stop reverse circulation to the radiators, sorry I cant help with your wiring as it is a heath robinson set up

 

[mrStat]

You really need to rewire your heating system into a junction box, most modern controls are not big enough to have that many wires in them. Looking at a wiring diagram for the 423 Coral, looks like this is configured for gravity type systems and I am guessing you do not have a room thermostat anywhere...

Additionally, the grey and the orange from the zone valve are not in use, this would simplify the whole process... But, here goes...

-> Set the SunPro to Gravity mode (Switch with a P&G on the rear, needs to be set to "G")...

1.RED MAINS (A) / BROWN BACK BOILER (E)
- L Terminal on SunPro

2.BLACK MAINS (A) / BLUE HW PUMP (D)
- N Terminal on SunPro

3.BLUE HONEYWELL (C) / BLACK CH PUMP (B) / BLUE BACK BOILER (E)
- N Terminal on SunPro

4.BROWN HONEYWELL (C) / RED CH PUMP (B)
- 4 Terminal on SunPro

5. EMPTY

6.EMPTY

7.BROWN HW PUMP (D)
- Join to wire currently located in 8 and terminate to 3 on SunPro

8.BLACK BACK BOLIER (E)
- As (7)


Good luck and like @ianmcd said, I'd strongly advise you get this lot rewired properly as you can get better control from your system. You have a complete hash of a system there that could really benefit from some updating.