Replaced Programmer, CH won't turn on now (But HW will)

[halfmarathonmike]

Hi,

Old programmer was blank one morning, replaced timer unit, then realised it was the 3 amp fuse next to the boiler, replaced that fuse - and the new programmer is up and running. (I did try putting back the old timer, but it tripped the house and blew up)

I am currently using the old backplate for the new timer as it fits , but we now can't get the central heating to run. I haven't moved any of the wires from the previous programmer.

Help! The house is beginning to get a bit cold and a bit damp!

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• halfmarathonmike
• 7 Oct 2013
• 1

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• halfmarathonmike
• 7 Oct 2013
• 1

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• halfmarathonmike
• 7 Oct 2013
• 1

 

[slapper]

Get an Electrician in then.........seemples

 

[45yearsagasman]

Have you set the jumpers on the back of the programmer correctly? Looks like you have a Y plan system.

 

[andytw]

Do you have gravity flow hot water (G) or a fully pumped system (P). ?
I can see you have the switch on the back of the programmer set to G for Gravity.
From the instruction sheet......

"The programmer must be set to the type of system it is to control.
The link on the back of the unit has two settings – P and G.
P = a fully pumped and controlled system – allowing
heating and hot water to be set separately.
G = a gravity-fed hot water system – which does not allow
independent setting of heating without hot water, though
hot water can be controlled alone"

What type of programmer was removed ? If you can state that, then it is possible to see if the wiring would need to be changed.
From the instruction sheet......

"Check the chart on the next page to compare terminals and if necessary, change the wiring of the wall-plate to suit."

 

[halfmarathonmike]

Hi guys,

Taken an image of the back of the old programmer (and also of the new backplate which I haven't mounted)


The system runs off a gas boiler, connected to the HW tank and CH via 3 way valve

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• halfmarathonmike
• 7 Oct 2013
• 1

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• halfmarathonmike
• 7 Oct 2013
• 1

 

[andytw]

Wiring is the same. You hve a 3 way valve so system is fully pumped so you need to move the link on th back of the programmer to 'P'

 

[halfmarathonmike]

Changed it to P but no luck - the boiler isn't even firing when on CH only

 

[twgas]

I would suggest you check the 3 port, no heating, fuse blown, points to a prob away from the prog.

 

[matt1e]

Changed it to P but no luck - the boiler isn't even firing when on CH only

Don't worry about it,it's because on setting "G" the programmer also turns on it's hotwater relay to fire the boiler when CH only is selected whereas on setting "P" it doesn't, the 3port does (or in your case, isn't)

I would suggest you check the 3 port, no heating, fuse blown, points to a prob away from the prog.

I agree, check the roomstat also

Matt

 

[halfmarathonmike]

Hi Chaps,

Turned out that our thermostat was so uncalibrated it was untrue, and this was the weak link.

Thanks for all your input.