EPH Combi Pack 4 Thermostat Wiring Diagram

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About This Diagram

This diagram is redrawn from page 1 of the EPH Combi Pack 4 Thermostat Wiring Diagram, and we offer it completely free and in English. We have also categorized it in the Thermostats (HVAC & Water Heating) section on Diagramverse, and it has been rated by 1 user with an average rating of 5.0. If you have any specific questions about the EPH Combi Pack 4 Thermostat Wiring Diagram, we suggest checking the Frequently Asked Questions (FAQs) section.

Printable EPH Combi Pack 4 Wiring Diagrams

EPH Combi Pack 4 Thermostat

Wiring Instructions

Before you start

This EPH Combi Pack 4 diagram shows the EPH 4-channel hardwired pack (CR4P, CR422P and CR428P). The pack contains an R47 4-channel programmer, a WRP pipe/cylinder thermostat, three CM2 room thermostats, four 2-port motorized valves and a 14-terminal wiring centre. ZV1 is the hot water valve and ZV2 to ZV4 are the heating valves. Some CombiPack4 kits instead come with a battery-powered RFRP-OT thermostat and an RF1A-OT wireless receiver. If that is your kit, this layout does not apply: wire the receiver from its own terminal diagram.

• Tools: insulated screwdrivers, wire strippers, a multimeter or approved two-pole voltage tester, cable labels and bootlace ferrules for stranded cores.
• Cable: the sources do not specify a size. Every circuit here carries 230 V, so use mains-rated cable with an earth conductor, sized to your local wiring regulations. Each valve has five cores: brown, blue, orange, grey and earth.
• Supply: feed the whole system from one 3 A fused spur. The 3 A fuse is the only protective device the system relies on.
• Isolation: switch off and lock off the spur, take out the fuse and prove the circuit dead before you touch any terminal.
• Who should do it: this is mains wiring that controls a boiler. Have a qualified electrician or heating engineer do it, and check whether your area requires the work to be notified or certified.

Read the boiler installation instructions before you wire anything. Boiler wiring varies: some boilers need a permanent live supply, some need a pump overrun, and some need a volt-free signal from the valve limit switches instead of the switched live shown on terminal 13. If your boiler needs any of these, its connection will differ from the drawing.

Step-by-step wiring

1. Mount the wiring centre, the R47 programmer and the thermostats. Put each CM2 about 1.5 metres above the floor, in the zone it controls, away from direct sunlight, radiators and drafts. Fit the WRP to the cylinder as its instructions describe.
2. Run the supply from the 3 A fused spur to the wiring centre: Earth to 1, N to 2 and L to 3. Keep the spur off.
3. Fit the two links in the wiring centre: 12 to 3 (live for the orange valve cores) and 14 to 2 (neutral for the blue cores, the boiler and the pump).
4. Power the R47 from terminals 1, 2 and 3. Then connect its outputs: Z1 ON to 4, Z2 ON to 5, Z3 ON to 6 and Z4 ON to 7.
5. Wire the WRP: COM to 4 and N/O to 8.
6. Wire the room thermostats on their COM and N/O terminals: CM2 (1) to 5 and 9, CM2 (2) to 6 and 10, and CM2 (3) to 7 and 11. Always use the N/O contact, which closes when the room calls for heat.
7. Connect the valve motors. Run the brown cores to their own terminals: ZV1 to 8, ZV2 to 9, ZV3 to 10 and ZV4 to 11. All four blue cores go to 14.
8. Connect the valve switches. All four orange cores go to 12, all four grey cores go to 13, and every valve earth goes to 1. Terminals 12, 13 and 14 each take several cores, so ferrule them and make sure every strand is clamped.
9. Connect the boiler: L to 13, N to 14 and earth to 1. Do this only if the boiler manual agrees with this arrangement.
10. Connect the circulating pump in parallel with the boiler: L to 13, N to 14 and earth to 1.
11. Label every cable, tug-test every terminal, dress the cores neatly and refit all covers.

Testing and start-up

Before you apply power, check that there is earth continuity from terminal 1 to each valve, the boiler, the pump and the spur. Also check that there is no continuity between live and earth.

• Switch on the spur. Measure about 230 V between 3 and 2, and between 3 and 1.
• With every programmer channel OFF and all valves closed, you should read 0 V between 13 and 14. The boiler and pump should stay off.
• Turn Z1 ON and turn the WRP up. You should read 230 V at terminal 4, then at 8, and ZV1 should drive open. When it is fully open, its orange–grey switch closes, terminal 13 goes live, and the boiler and pump start.
• Turn the WRP down. ZV1 should close and terminal 13 should go dead, as long as no other valve is open.
• Repeat the test for Z2 with CM2 (1) and ZV2, Z3 with CM2 (2) and ZV3, and Z4 with CM2 (3) and ZV4. Each time, confirm that the correct valve moves.
• Finish by setting the clock and switching times on the programmer and the temperatures on each thermostat.

Safety notes

• Every part of this system works at 230 V, including the thermostats and the valve switch cores. Treat terminals 2 to 14 as live whenever the spur is on.
• Terminal 13 can be live from any valve switch even when the thermostat you are working on is off. If the boiler has its own permanent supply, isolate that as well before you work.
• Never replace the 3 A fuse with a higher rating to cure nuisance blowing. Find the fault first.
• Earth every valve, the boiler and the pump at terminal 1.

Troubleshooting

Frequently Asked Questions (FAQs)