UPDATE!! Wires for thermostat

[emailrob]

No, I didn't disconnect the mains, I think one of the other posts thought I had taken it off for the picture, but I hadn't. The mains comes into 10 9 and 8 on the left.
So you're saying power into 1&2? Maybe whoever wired it did it the other way round. I will try it into 1 and 2 instead of 10 9 and 8 and the stat in where you said, and see if it makes a difference, and that mains power is still there.

It seems the power is wired into the external timer at the moment, this is perhaps why it is not working!!!

cheers

 

[emailrob]

well things have gone from bad to worse.

I tried to wire it to the 1 and 2, but got a bang (!) and now cannot get power at all to the unit. I've changed the fuse at the wall and it still does not work. Could the fuse on the board go? If so, I can pick one of these up at a DIY place to try, it's a 2A one. Or is it a specialised one?

Any ideas? I've taken to board off and two of the track connectors on the back don't look very good, so not sure if it has caused a problem here? Looks a bit black on a couple of the contacts.

I'll take the board to work tomorrow and get one of the lads to look at the connections, and see if they can re-solder them.

Any help would be great as I don't have any heating or hot water now!

If all else fails, where can I get a new PCB from (maybe second hand) or a new board fuse to try first??

 

[breezer]

sorry to here it has gone bang, yes you have probably taken out the fuse in the consumers unit too. you can get a new fuse at Q & B .

one of the lads at work can solder wires where the tracks were. to have that kind of bang you have got a live and neutral crossed over. to avoid further "bangs" get an electrican in to do it for you and to check all the wiring connections as you have unfortunately got one wrong.

 

[MANDATE]

The room stat shown in your wiring diag. has three wires on terminals 5, 4, & 3. Term. 5 is neutral.
Term. 4 is 'live' going to the room stat TL( probablely thermostat live)
Term. 3 is for wire coming from the room stat then on to pump I would think H (Heating.

If you have no room stat then a link is needed to get from term 4 to term. 3.
If as say your room stat is a two wire job then surely it must go in place of the link across term.s 4 & 3.
It has been suggested you may have three terminals on your stat and in addition to Comm(live) you can have either 'normally open' or 'normally closed'. if this is true you may be using the wrong one.
To me when the stat is set high you need an electrical path through the stat so the boiler/pump operates just like the link. When the stat is set low that path needs to be broken.
I would suggest before wiring in to the terminal block in lieu of the link ( terminals 4 & 3)you put a continuity meter across the stat terminals and turn the stat up to ensure the path is there and down to ensure it is broken

 

[MANDATE]

I think your new problem stems from the difference in room stat types
If your new stat has only two wires ie a'live' from term 4 to stat and a 'switched live' from stat to term.3.( basically a on/off switch) and you have I understand connected this to term. 5 then that will have caused the short circuit .
The stat shown in the wiring diagram has three wires 1 being a neutral which is correctly shown to term. 5. the 'live' and 'switched live' going to term.s 4 & 3.
To avoid short circuits electricity must pass through a 'load' be it a light, element or motor etc. but a on/off switch is not a 'load'
I believe the 3 wire room stat incorporates a load, hence the neutral and the 2 wire has no 'load' and still no load if connected to term 5.

 

[emailrob]

thanks mandate.

Boiler is back up and running, so I'll wait a bit then prob get someone in to look at it

Thanks for yours and the others help.

 

[emailrob]

Well I took the easier but not as good option, and got a electro mechanical timer put in place. Plug into PCB set time and it worked.
That's it. I'm leaving it now. It's not 7 day, it doesn't have a thermostat, but it works, and believe you me, the wife is more than happy..!!

Thanks for all the advice. Screwfix have a pretty good returns policy so fingers crossed I can get my other cash back