Replacing with SuperSwitch Central Heating Programmer with Drayton LP711

[eezzeeman]

Greetings fellow DIYnot-ers!

Would appreciate immensely some advice re a small DIY job i am about to embark on. And please forgive me for moments of painful description i am a relative noob.

We have a Gledhill PulsaCoil boiler (pic) and it has been controlled by a Superswitch Central Heater Programmer (pic) which, after +10 years of service , the mechanical buttons themselves have cracked/gone bust.

Looking to upgrade to a digital timeswitch and have been advised to install a Drayton LP711 as it suits our purposes. We only require a 1-channel switch as the boiler only serves the hot water for bathroom/kitchen etc (heating is separate)

I just need some confirmation with regards to the wiring. In the picture included below for the SuperSwitch the labelling for existing wiring seems to be (from left to right)

Lower stack
N in/out= Neutral (Blue) - and black wire(?)
L in = red
L out (ch only) = (no wiring)
L out = brown wire (meant to Live?)
Not used

Upper stack - which is causing me major confusion
N in/out= seems to serve the mechanical timer and LED for the timed switch (which in turn is served by the 'on peak' switch below the panel
L in = red
L out (ch only) = red
L out = black for LED / red
Not used / red

From what i can derive from previous forum/posts the Drayton wiring - the configuration is:

N = Neutral (Blue)
L = Live (Brown)
1 = COM (Black)
2 = No wire (would be OFF)
3 = ON (Grey) - i don't have a grey...?
4 = No wire

Making a huge assumption - by upgrading from the old Mechanical Superswitch to a newer digital Drayton - in terms of the wiring, i do not need to consider the v messy configuration of the upper stack of wires and should be simple task of rewiring the lower stack with accordance to colour code?

Thanks in advance!

 

[cjcoffin]

It looks as though your upper row of terminals only has internal connections but you need to check this.

If so, you need to wire the Drayton LP711 thus:

N - blue and black
L - red
1 (COM) - link to L
2 (OFF) - n/c
3 (ON) - brown
4 - n/c

You also need to link the two green/yellow earth wires together using a separate piece of choc block. Do not connect them to any of the Drayton terminals.

HTH

 

[eezzeeman]

Thanks cjcoffin

Appreciate that feedback!

 

[eezzeeman]

In addition - i've been informed that the LP811 is also suitable - but i can't seem to identify the difference between the LP711 and the LP811

Anyone with Drayton expertise able to comment?

Much appreciated

 

[cjcoffin]

The LP111 has the same programme every day. The LP711 can have 7 different daily programmes. The LP811 can be configured for either, and also weekday/weekend programmes. Depends what you need and how much you want to pay.

 

[eezzeeman]

Thank you again cjcoffin

Based on your expert opinion - it seems that the LP811 is the most versatile and given that i've found a source which prices it cheaper than the LP111 and the LP711, i'll take that option!

Cheers!

 

[toto123]

Seems like i have a v similar issue but with rather worrying consequences

I installed mine with guidance from Drayton technical staff on the phone, and whose instructions matched cjcoffin's above.

Power back on and everything fine. The default settings switched on the boiler at the default times. And was able to advance the hot water at the push of a button.

24hrs later....

We noticed that the plastic unit was warped/ melted on the right hand side! We immediately switched off the mains and removed the unit from the backplate

Please see the picture attached:

The picture with the back of the unit where the melt has occurred - there is a black (capacitor?) underneath which maybe the source of the heat that melted the casing. But at this point i have no idea.

Any assistance as to what went wrong?

Thanks in advance

 

[stem]

Isn't the Gledhill Pulsacoil heated by electricity?

If so you have connected a programmer designed for switching less than 1A to operate the controls associated with gas/oil boilers to an electric heating system taking 13A or more. The overload will have caused it to melt.

 

[Gaz the Sparky]

I would say at a guess with looking at the size of the cabling in that picture Stem is right.

It looks like you have installed a normal heating programmer which is rated at 3amps.

You are requiring a high rated programmer capable of switching a 13amp load

If the above is the case that is why your controller has burnt out as you have overloaded it

Show us a picture of your old controller and boiler it’s controlling

 

[stem]

It looks like you have installed a normal heating programmer which is rated at 3amps.

It's even less than that. 2A restive, 1A inductive.

 

[Gaz the Sparky]

It's even less than that. 2A restive, 1A inductive.

View attachment 137536

Ah I didn’t look too closely at that but you are right. I just saw the 3amp fuse rating on the backplate

 

[stem]

If our assumptions are correct. Let's hope 'eezeeman' didn't go down the same route!

 

[toto123]

@stem
@GaztheSparky

thanks guys - appreciate the detailed feedback!

Coincidentally - the pictures that eezzeeman provided are almost identical to my set up so i hope those pics will suffice because my old Superswitch thermostat has been disposed of!

I will sort out getting a more reputable electrician. But just to be clear, does this mean that my choice of the LP711 is inappropriate for this set up? Or is it a case of rewiring?

Thanks again


Will have words with my so-called 'electrician'...

and yes - eezzeman - if read the thread above!!

 

[eezzeeman]

Hello all

Thankfully i have not yet gone ahead with the full installation

Stem and Gaz The Sparky - thank you for the invaluable feedback

Toto123 - sorry to hear you melted your box!

Looks like i will call in some professional help - but would also like to ask the same question as Toto123

Does this therefore mean that the LP711 is no longer an appropriate choice? I can return it for something more suitable - any recommendations?
(again - i only require a 1-channel as this only services the On-Peak immersion heater)

Thanks again guys!

 

[stem]

But just to be clear, does this mean that my choice of the LP711 is inappropriate for this set up?

The LP711 is not designed for switching the currents associate with electrical heating, so is completely the wrong timer to use for such heavy loads. I am amazed and quite worried that "Drayton technical staff" gave you such dangerous information. That melted timer could have quite easily started a fire.

There are a lot of immersion heater controllers out there, but a lot are designed to work with the 'off peak' supply. The 'on peak' is usually operated manually as / if required. For a single immersion heater rated at 3kW, any timer will do provided that its switching contacts are rated at 13 amps or more.

Boost timers are also available that will give you a set time for the 'peak' boost on the press of a button.