Wiring a Horstmann Electrisaver to Honeywell Wiring Centre?

[stu550]

I'll try to keep this simple

I want to wire a Horstmann Electrisaver into the Honeywell Sundial Plan Wiring Centre to boost the central heating.

I understand the Honeywell wiring centre connections and what does what etc at that end

The new Horstmann switch instructions are here: http://www.horstmann.co.uk/download...ing/Electrisaver-UserandInstallationGuide.pdf

It states it requires separate connections as follows:
Neutral in
Neutral out
Live in
Live out
Earth in
Earth out

I recognise that if this was being used for an immersion tank application all those would be necessary and should be used.

However, because of the location the new switch is going and the fact that it is being wired into the wiring centre, is it actually necessary to wire it using 6 different connections?

For example, could I just wire it as switch with a neutral and earth from other cables (frost stat with live and supply for boiler) that comes from the wiring centre? I'd like to fit the new switch between the wiring centre and the boiler - fortunately this is where the boiler controls go so I'd like to utilise them if possible. I can't easily add new cables to where I want the switch to go.

Hopefully that makes sense.

Thanks in advance.

 

[D_Hailsham]

What controls do you have for your central heating?

Timer or Programmer? Make and model

Room thermostat? Make and model

 

[stu550]

The programmer is a Hortsman Centraplus C27 and the thermostat is a Honeywell DT90e.

Hope that helps?!

 

[D_Hailsham]

The programmer is a Hortsman Centraplus C27

You can do all you want using the Advance button.

Pressing the button when the heating is OFF will turn it ON setting, and vice-versa.

The hot water can be put on for an extra hour using the Boost button.

C27 User Guide

 

[stu550]

Thanks, I know that.

But I don't want guests in the rental property to be able to access the controls... Should have explained that bit earlier.

 

[D_Hailsham]

But I don't want guests in the rental property to be able to access the controls... Should have explained that bit earlier.

It would have helped.

You mention a Sundial wiring centre. Please post which Plan (S or Y) you have as a motorized valve has to be opened when boosting the heating.

The S plan has two valves (left pic); the Y plan has one valve (right pic).

View media item 11762 View media item 5946

 

[stu550]

Its a Y plan. Here's a photo:

Untitled

• stu550
• 15 Apr 2013
• 2

I KNOW how to wire it to operate if I had direct access to this wiring centre.

BUT - I can't wire into this easily and therefore want to know if I can wire it into the frost thermostat (that has a constant live and switched live) so it will sort of operate in parallel to the frost thermostat. The frost stat is wired so the room thermostat still operates so it wouldn't override that if you see what I mean.

I would then need to take a neutral off the supply to the boiler as that wire is also easily accessible.

 

[D_Hailsham]

The frost stat is wired so the room thermostat still operates so it wouldn't override that if you see what I mean.

The only reason the frost stat and room stat do not interfere with each other is due to the temperature ranges they control. The room stat will come on if the temperature drops below about 20C (timer permitting), while the frost stat comes on when the temperature drops below 5C, irrespective of timer setting.

The sw-live from the frost stat should be connected the valve white wire. As you have a Y Plan the hot water may also come on - it depends on if the HW is On and calling for heat.

The Horstmann device, as it has no built-in temperature control, will turn the boiler on and keep it on until the boiler stat turns it off or the Horstmann comes to the end of its timed on-period. The room stat will be completely over-ridden.

 

[stu550]

The Horstmanm device will turn the heating on until the time runs out or the room stat is satisfied. The way it is wired means the room stat is sort of wired in series to the frost stat. Not sure why it was does like that but it works.

Anyway, this is not really helping to answe my question I'm afraid...

 

[matt1e]

no you don't need to use all the connections (L in,N in, E in, & L out is all that's req)
yes you can connect it directly to the wiring centre,you can pick up all you need from the programmer terminal block (L,N,E, & terminal ch on) or you can wire it into the programmer itself

forget about wiring to the frost stat

The frost stat is wired so the room thermostat still operates so it wouldn't override that if you see what I mean

If that is the case then the frost stat isn't wired correctly and you should correct it so that the roomstat is off overridden by the frost stat

Matt

 

[stu550]

Is there any reason I should piggy back this override switch onto the frost stat though and take a neutral from the boiler supply?

Can you explain why the frost stat needs to override the room stat?

 

[matt1e]

Can you explain why the frost stat needs to override the room stat?

Because a lot of people control their heating via the room stat i.e
roomstat up = heating on
roomstat fully down = heating off

now lets say they go away for a week at crimbo and turn off the heating via the roomstat and while they are away it gets really cold

the frost stat needs to be able to switch on the heating regardless of the position of the room stat

 

[stu550]

Ah, yes. I are what you mean. I didn't think room stats went that low. Anyway, mine has a set back of 7degrees so should be okay.