Replaced timer - now no central heating :-(

[billybargain]

Hi,

I've just replaced a Danfoss 102E5 programmer/timer with a Hostmann c27 from screwfix - to program my Potterton Prima boiler

I did this as the Danfoss could only work with hot water on or hot water +heating on at the same time but not heating on it's own.

Since swapping over the boiler fires up when the Hot Water is on and heats the water (the red hot water light is lit on the c27) but the boiler doesn't fire up when I switch central heating on (the red CH light is lit on the c27).

I've attached a photo of my wiring. Any ideas gratefully received.

Cabling:

I've got 4 sources of cables (sorry you can probably guess I'm not an expert) : Boiler, Pump, fused rocker switch and hole in wall behind timer.

Cabling:
N = 4 blue cables (1 from each source)
L = 1 red cable from hole in wall
1(HW off) = no cable
2(CH off) = no cable
3(HW on) = 1 brown cable from boiler
4(CH on) = 1 brown cable from pump


There is a brown cable coming from the rocker switch and a yellow cable (not earth I don't think) from hole in wall which were terminal blocked before so I've left them that way.

As I say, Hot water works, Heating doesn't

Many thanks in advance
Brett

 

[bengasman]

What does your wiring centre look like?

 

[billybargain]

Hi mate,

Where would I find that please?

Cheers
Brett

 

[gassafeman]

What system do you have?

y plan?
s plan?

None of the above?

You need a closing sequence to run c/h independantly.

EDIT: as Bengasman has stated... wiring centre. IGNORE COLOURS

Paul.

 

[billybargain]

Thanks for your prompt replies

Where would I find the wiring centre? I'll then post a picture.

cheers again
Brett

 

[bengasman]

...Where would I find the wiring centre? I'll then post a picture....

At the other end of the cable.






Normally near the cylinder/valves/pump

 

[billybargain]

Cheers! am on way with camera

 

[billybargain]

Hi, I've found that the red, blue and yellow cables (hole in the wall) come from the room thermostat.

I can't find the wiring center (but that might be in the loft)

Also when I switch the thermostat down it fuses the 3amp fuse.

Found the ch pump which seems to be turning ok.

Cheers again
Brett

 

[bengasman]

It sounds like you might be needing a pro to sort this out; the combination of water, copper pipes and 230V can lead to nasty surprises. The absence of a wiring centre could well mean that the wiring was botched before you started on the timer.
No offense, but it doesn't sound like you are very experienced with controls/electricity.

 

[matt1e]

Hi,

I've just replaced a Danfoss 102E5 programmer/timer with a Hostmann c27 from screwfix - to program my Potterton Prima boiler

I did this as the Danfoss could only work with hot water on or hot water +heating on at the same time but not heating on it's own.

3(HW on) = 1 brown cable from boiler
4(CH on) = 1 brown cable from pump

As I say, Hot water works, Heating doesn't

you have gravity hot water and pumped central heating mate you cant have heating on its own (well not with just a new programmer anyway)

where is that yellow connected and have you fitted a new room stat?

matt

 

[cozzmic]

What type of boiler have you got?
Sounds like a gravity HW and pumped CH which will only work HW and HW/CH

 

[billybargain]

What type of boiler have you got?
Sounds like a gravity HW and pumped CH which will only work HW and HW/CH

I think that's the type I've got i.e. hotwater tank in the loft, pump downstairs in the garage??

 

[billybargain]

you have gravity hot water and pumped central heating mate you cant have heating on its own (well not with just a new programmer anyway)

where is that yellow connected and have you fitted a new room stat?

matt

Hi Matt,

I didn't realise that I couldn't have both independantely - grrr

the yellow is in a terminal block that goes to the load on the therostat - I think it needs to go in to CH-on according to the wiring diagram. I can't understand why it's terminal blocked - does that mean the stat hasn't been doing anything?

Cheers
Brett