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Feb 21, 2023
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Hi
Installing single zone ufl with Grundfos pump/mixing valve and heatmiser thermostat - not crystal clear from the diagrams how the control connection to LR/LS should be wired (i.e. red on the pump control diagram)

Any advice much appreciated!


ufl thermostat.jpg
 
It states on the instrucions, that LS/LR (A1 and A2) go to the boiler? Are you wiring it differently?
 
Yes - installing this single room underfloor heating kit


Which replaces the radiator in a single room
I am assuming that the thermostat should control the Grundfos pump/mixing valve for the room, independent of the boiler
 
At a guess I’d say the wiring must connect back to the boiler to operate the heating independently, or possibly using a motorised valve.
 
Looking at the instructions, if you’re replacing a radiator, the ufh is controlled via a trv, not a room stat. The other option mentions a zone valve (motor valve).
 

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Hi jbatexning
If you are just asking about the connections between the stat and the supplied junction box:
(obviously you provide wiring from the fused spur as illustrated bottom right, and then🙂
Blue (N) to stat terminal (N) !
Black (L) to stat terminal (L) and link to stat terminal (A2)
Red (SL) to stat terminal (A1)
Grn/yel (E) insulate safely at stat, unless there is a E terminal in the stat, in which case connect it there!

If you buy 3 core plus earth cable to connect the stat, it will likely be: Brown, Grey, Black & bare copper (in cable), or green/yellow (flex)
In which case typical use of these colours is
Brown - permanent live
Black - switched live (put a brown sleeve on it)
Grey - neutral (put a blue sleeve on it)
green/yel - earth of course.
 
ChrisB1982 - It is option 2 that I am installing (own pump, blending valve, and room stat)

Basher – it was the A1 and A2 connections I was unsure about, and understand now :
live link L to A2, and red LS to A1

Many thanks for your help!
 
  • Agree
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