Wiring up Horstmann RF room stat

[nigeldodd]

Hi, I have replaced an old programmer with a Drayton Lifestyle LP722 and decided to replace an old Honeywell mechanical (bimetal strip) room stat with an RF one. I bought the Screwfix Horstmann HRFS1 Stat but am not sure how to connect the two up. The boiler is an Ideal Mexico CF80 from the 1980s and the whole system is configured in the Sundial "Y" plan format. The room stat shows a wiring diagram for 230v application and a diagram for volt free application. Any suggestions as to whether or not I need to use 230v or volt free wiring? If you need any more info to help please reply and I will supply more detail.

thanks
nigel

 

[seco services]

L - call from programmer heating on
SL - switch live to white wire of your 3 port valve.
N - neutral.

 

[holdenmilner]

Hi, I too have just purchased the same thermostat and want to connect it to my existing LP722 programmer. I have a gravity fed Oil burner and I am stumbed to which wires to connect to the new thermostat. I have taken the front panel of the LP722 where it is has N, L (1&2) and then a brown and a blue in 3&4 . Which wires do I extend to go into the new Thermostat? Matt

 

[seco services]

n0 4 is your ch on terminal.

 

[holdenmilner]

Okay so basically I run a L and N wire(s) from 1 & 2 from the existing programmer box to L & N on the new thermostat? And then run a wire from terminal 4 on the programmer to SL(on) on the new thermostat? Is that it three wires? Matt

 

[seco services]

take the blue out of terminal 4 thats gos to SL ON on the stat. (top right)
put a wire in terminal 4 to the L of stat. (top middle)
and the N go's to N of the programmer. (bottom)

 

[holdenmilner]

I will give that a go thanks. I assume I keep the loop wir (defailt) as is. this is a little red wire that connects L and L In on the thermostat. It was already there when purchased. Matt

 

[seco services]

yes

 

[holdenmilner]

Well it works thanks. However and just to make sure I am doing this correctly, I have set the programmer to on (constant) and therefore heating will (should) only fire up when temp drops below what new stat is set to. This seems to work but the hot water is now on constant all the time. This was the case before I wired up new stat. When heating came on so did the water. I assume because its an old system this is normal. I dont suppose its a bad thing to have hot water on all the time is it?
Matt