Spark from CH timer - advice required please

[Pioneerx]

Hi all,

Yesterday my mains trip switch triggered and eventually narrowed it down to the CH/Socket electrical circuit. When I turned the mains on with all other plugs removed the trip activated and saw sparks from the timer switch.

After removing the cover (RWB2) this is what had happened.

Untitled

• Pioneerx
• 27 Nov 2014
• 1

I bought a new programmer Drayton T721R replaced the backplate with wires in same positions but when the 3 amp spur plug was replaced 1st the fuse went,then next time the trip was triggered.

I believe my system is a Fully pumped system with one three port mid-position valve (Danfoss HSA3)

Is there something I am doing wrong or is it another part of the system causing the problem?

Many thanks for looking

 

[Jackrae]

That earth wire shouldn't be connected to terminal No1
You effectively shortened out the mains to earth.

Read the wiring instructions (step 2 of the instructions provided with the unit) that came with the timer and then convince yourself that the earth wire shouldn't go where you connected it.

Apart from that it begs the question "why did you change the termination plate" as most are fairly standard (3 or 4 channel programmers excepted) or is there something you aren't telling us

You also appear to have omitted to fix the termination plate to the wall/box/whatever.

By the way your new control unit is also goosed - many amps through fairlydelicate relay contacts is a kiss of death

 

[Pioneerx]

Thanks for reply Jackrae.

The picture is how the RWB2 backplate was wired and since it was damaged just replaced it in same wiring order as the shop advised.

So is the earth not needed for T721R?

 

[oldbuffer]

Its possible that whoever wired the original used the earth wire as the "HW Off" signal wire - stupid, but not the first time its been done. You need to find where the other end of that earth goes to, it may be to the HW Off lead on the three port valve, possibly via a wiring centre. The connections for your new programmer are exactly the same as the RWB2, so if the problem was with the old controller then it should have worked. It hasn't worked so:

a The problem has always been elsewhere in the system.
b. The failing of the RWB2 has caused a further problem elsewhere.

I think you need to get someone in to trace the wiring all the way through to try and determine what caused the problem in the first place.

 

[andytw]

You also appear to have omitted to fix the termination plate to the wall/box/whatever.

Looks like a slotted screw top right, bottom left out of sight.

 

[Pioneerx]

Looking at the HSA3 valve - the lever at the top was almost solid,I have moved it around and now moves much better,could that have been a cause?

I have traced the wires and yes the earth shown in the pic does go to "HF Off" as oldbuffer suggested.

 

[andytw]

Looks like the original fault was just a bad 'arcing' contact on the live in to the programmer. How about an 'after' photo now you have replaced the backplate ?

andytw

 

[Jackrae]

Andy,

Well spotted on the screw (and the invisible one off picture)

However that defect doesn't look like a faulty contact, especially with the tripping features that the writer explained in his enquiry. Something is wrong that has yet to be identified.

Can the writer reconfirm what terminal on the valve that the "earth" wire currently connected to terminal 1 on the programmer wall plate is connected to. A photograph of this connection on the valve would be useful.