CH controlled by thermostat even when programmer off

S

Stevex

Messages

35

• Feb 27, 2023

• #1

I've just noticed that with the CH programmer either selected off or timed off, the CH can still be controlled on/off at the room thermostat.
HW is controlled by the same programmer and is operating normally.
System is a pumped Y plan.
I take it the programmer is fubar?
Anything I can do to confirm or is it obvious the programmer is at fault; it's a Drayton Tempus 7.

 

S

Stevex

Messages

35

• Feb 27, 2023

• #2

The pic is of my programmer backplate.
1=HW off; 3=HW on; 4=CH on
With the programmer fitted and CH selected off I'm getting 240v at wire 4 in the junction box; I take it this indicates a fault in the programmer, with no wire to CH off at the backplate is the CH controlled by voltage at 4 @240v for CH on and 0v CH off?

 

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D

Deleted member 120897

• Feb 27, 2023

• #3

It does seem like the programmer and it doesn’t need a CH off, just HW off, which you have. Shouldn’t be getting 240vac at number 4 in junction box if that’s for the room stat.

 

S

Stevex

Messages

35

• Feb 27, 2023

• #4

Thx Chris, I'll get one on order then.

 

T

Timmy D

Esteemed

Gas Engineer

Subscribed

Messages

937

• Feb 27, 2023

• #5

Have you checked to make sure you’re not getting 240v at terminal 4 of the mounting plate with the programmer removed.

Just to make sure something else isn’t potentially wired wrong.

Also the mounting plate Earth isn’t connected.

 

S

Stevex

Messages

35

• Feb 28, 2023

• #6

Timmy D said:

Have you checked to make sure you’re not getting 240v at terminal 4 of the mounting plate with the programmer removed.

Just to make sure something else isn’t potentially wired wrong.

Also the mounting plate Earth isn’t connected.

Click to expand...

Thx Tim, good call; I checked it and there's no voltage at the back plate on t4, which confirms the programmer at fault.
I noticed the earth not connected, I'll sort that when I fit the new programmers back plate.

 

S

Stevex

Messages

35

• Mar 2, 2023

• #7

Fitted a Drayton LP822, it even used the same back plate as the old Tempus 7; all working normally.