Room thermostat not getting 230v

[Phil_in_Swansea]

Hi folks.
In the midst of redecorating I thought I'd change my old BG RS2 room thermostat for a newer Drayton rts2. Three wire plus earth, easy swap right, nope. Turns out my room stat isn't getting 230v, just 205v.
Wiring runs mains to block (234v) block to Drayton lifestyle 522, 522 to block (different L + N points ) block to Room stat.
After the 522 the voltage drops to 205v which may explain why the new electronic Rts2 won't work properly.

Help please, any ideas or easy fixes very much appreciated.
Thanks.
Phil

 

[flameport]

What are you measuring the voltage between, and what are you using?

 

[Phil_in_Swansea]

Hi. Digital multimeter, live and neutral.

 

[Doggit]

As you know the route for the wiring, use the multimeter to check each point in turn, and see where the voltage drop occurs. It may be a poor or loose connection, or even corrosion giving a high resistance.

 

[flameport]

Hi. Digital multimeter, live and neutral.

Make sure that the neutral is actually connected - if it's loose/unconnected at one end, measuring voltage at the other may give misleading results due to the capacitance of the cable.

 

[Phil_in_Swansea]

Yeah thanks guys. Having popped the 522 off the backplate I think I need to read up on what the wiring should look like because it looks as though the neutral from the stat doesn't actually connect back anywhere, it goes into the connector block but the neutral from there doesn't actually connect at the 522 backplate... Or anywhere.

 

[Doggit]

Try this
http://www.draytoncontrols.co.uk/sites/default/files/LP522 (U.&I. Guide).pdf

 

[ban-all-sheds]

After the 522 the voltage drops to 205v which may explain why the new electronic Rts2 won't work properly.

It's required to work down to a supply voltage of only 207V, so I doubt they'd manage to make something that wouldn't go at 205V.

You haven't really got 205V there, with no neutral.

 

[ericmark]

Yeah thanks guys. Having popped the 522 off the backplate I think I need to read up on what the wiring should look like because it looks as though the neutral from the stat doesn't actually connect back anywhere, it goes into the connector block but the neutral from there doesn't actually connect at the 522 backplate... Or anywhere.

It would seem you have found the fault then. The BG RS2 room thermostat could be used as two or three wire, it would seem in your case was connected as a two wire device.