Central Heating - Programmer won't switch both h/w & c/h

[scottishhero]

Hi,

I've recently moved into a new property and i have an issue with the central heating/hot water in that i cannot get the programmer to switch both on at the same time!

The boiler is a British Gas 330+, the programmer is (based on a warranty sticker) 1997 Danfoss.

When for example the hot water is called via 'auto', or set manually to 'on', i am then unable to also turn the central heating on, the LED just flashes on then back off again. If both are set to 'auto' when the time comes around the LED's will flick between c/h and h/w probably until it burns itself out.

Based on your experiences is this likely to be an issue with the programmer or the wiring? I can't imagine that the previous occupier would have been able to live with this for the last 3 years (i'm assuming if its a wiring issue its been since british gas installed that boiler in 2011).

I can switch out the programmer obviously at a cost, i just want to get a few opinions in case i can debug it another way!

Regards,
Shaun

 

[D_Hailsham]

How many motorized valves do you have? There are two types - see pics.

View media item 5946 View media item 11762

 

[scottishhero]

Hi, there are two of these in the airing cupboard, one on a pipe coming from half way up the cylinder and one on a pipe just below the central heating pump (I think).

They are connected to different blocks in the junction box

Untitled

• scottishhero
• 23 Aug 2014
• 1

Untitled

• scottishhero
• 23 Aug 2014
• 1

 

[TCCHeating]

Sounds like the programmer to me. Remove the programmer from the backplate and put a link wire between live in and the hot water on and heating on wires. If both the valves open and the system works then replace the programmer

 

[D_Hailsham]

Sounds like the programmer to me. Remove the programmer from the backplate and put a link wire between live in and the hot water on and heating on wires. If both the valves open and the system works then replace the programmer

The live is the top terminal, which has a red on the left and two greys on the right.

The valves' 'on' wires are the brown ones, in the black cables.

 

[TCCHeating]

Yeh sorry, i'm carp at explaining! But what i meant was to put the link wires on the programmer backplate, rather than in the wiring center. That way you are testing the whole system, (cylinder and room stat included) rather than just the valves.

 

[scottishhero]

So linking out in the back of the programmer will cause the boiler to fire up indefinitely while its switched on right? I'll give this a go in the morning then

 

[TCCHeating]

So linking out in the back of the programmer will cause the boiler to fire up indefinitely while its switched on right? I'll give this a go in the morning then

Yes. turn the power off and take the programmer off. Make the links on the backplate. Then turn the power back on and turn the room stat and cylinder stat to maximum. The boiler should fire and both valves should be open. Then turn the room stat down to minimum, the heating valve should close. Then turn the cylinder stat down to minimum, the hot water valve should close, and the boiler should turn off. If everything works ok, get a new programmer.

 

[scottishhero]

Thanks.

You say the valves should open and close, is there a way to tell this other than rads getting hot? ie on the valves themselves or something?

 

[D_Hailsham]

You say the valves should open and close, is there a way to tell this?

There is a lever on the end of the valve, which is used to open the valve when filling the system.

When the valve is closed, the lever will be stiff to move from the Auto end to the Man end. It will also return to the auto end when released.

When the valve is open the lever will move easily in the slot and feel 'loose'.

You may have to push/pull the lever first: depends on make of valve.