salus rt500rf programmable thermostat with sabre HE25 boiler

31 Oct 2008
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United Kingdom
Hi, im wiring the Salus RT500RF programmable thermostat to a sabre HE25 boiler, which doesn't have a wiring loop/jumper (the one you usually remove for the thermostat). The salus stat has 5points;

1. NC - Normally closed, so ignore this one (In the diagram for 230V application, this is labelled SL (off) - Heat off*
*Not Normally Used
2. COM - Volt Free Feed
3. NO - Switched Live (Volt free)
4. L - Live (230V Feed)
5. N - Neutral

This is a 4wire volt free application. I've wired the L and N from the stat into the L and N of the power point in the boiler, as it should be.
But since the boiler doesnt have a stat wiring loop, im not sure where the COM and NO wires from the stat go to, inside the boiler.

There is a time clock in the boiler with two wires. To wire a thermostat, they have bypassed one of these wires through the stat. instead of going straight to the point on the boiler where this wire originally was, it goes to point 3 on the stat and then point 2 from the stat goes to where the wire from the clock was, before.
I dont know if you can see my albums, but i have the wiring diagrams from the sabre boiler manual in there (Figures 38 and 39).
Figure 38 is the factory configuration (2wires from time clock going straight to boiler), and 39 is how the stat should be wired according to Sabre.
But firstly, the thermostat doesn't have 2 & 3 (like the stat shown in the Sabre manual), it has COM and NO. Secondly, since there is no loop for where the stat should be wired to in the boiler, im not sure where to wire the COM and No from the stat. Does this same wire go through COM and NO, instead of 2&3? And if so, does the time clock's wire go to NO, then COM goes to the boiler, or... does the wire from the time clock go to COM and then NO goes to the boiler?

Really appreciate any help on this.
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for anyone who reads this, n maybe needs help with the same issue, just zoomed into the picture and noticed that 2 on the stat, according to sabre, is COM and 3 is ON. Not sure if ON is same as NO (it is 'NO' as according to salus). Will find out wen its wired up. Or leme kno if u kno. Wont be wirin it up till monday. Would have been great if they'd put the COM n NO labels in the actual printed manual, big enough to notice :rolleyes:
Had to zoom in quite a bit to notice what it said, on the pc pic.
Im no electrician, but seeing how this breaks the circuit to the time clock makes sense now. i feel kinda stupid 2b honest :LOL:

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