Still confused with wiring up a vaillant eco-tec

simond and londonboy are correct

3 - should ideally be connected and feed controls
4 - is s/live from controls

This (like many other boiler makes) is so that the external controls are disconnected on a reset

matt[/url]
 
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Maybe I got the facts wrong, but the ecotechs I know, are combis.
What do you need a wiring centre for on a combi?
 
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Didn't know that, never seen an ecotec heat only.

Just realised I forgot the most obvious question: why didn't the installer install the controls? :confused:
 
bengas
Ecotec 400 series are open vent heat only
& ecotec 600 series are sealed system heat only
both nice units and so far touch wood our customers have been very happy with them.
 
They should be. If installed properly, vaillant is not a bad product; it is the vaillant attitude that stops me from using them.
If I am totally honest, (which I am not, as I am a plumber) on the whole, I don't think there is a whole lot of difference in quality between vaillant and wb as far as the actual boilers are concerned.
 
would agree that WB & Vaillant are good units, but WB are just as crap at customer service - still awaiting certificates for course I did with them in 2006 gave up asking for it a long time ago.
 
Not being funny Kev, but who gives a single solitary 5hit about a certificate, unless it stops you from being accredited?
I don't even get asked for my crapita card, (which I still didn't receive :rolleyes: ) let alone for anything else.
 
The problem with taking the supply to the wiring centre from terminal 3, and therefore to the programmer, is that terminal 3 is only live when the boiler is switched on at the boiler ON/OFF control. So, if the boiler is switched off for any reason, e.g away on holiday, the programmer will also stop.

The way to avoid this is to take the feed to the wiring centre from either the fused spur or the L and N terminals on the boiler. Vaillant show this in their wiring diagram. Although a wire is shown from terminal 3 to the thermostat, this is not strictly necessary as the thermostat will get its supply from the programmer; the only wire required is the switched feed to terminal 4 .

 
Your diagram is for a combi, G_Hailsham.

As you will be aware, it could be adapted for a volt free programmer in an S or Y plan system.

The German boilers typically have a live 'send' and a live 'return'. On older Vaillants the overheat stat was wired between PLive and term 3. If you took the controls from PLive you bypassed the OH stat.

Even on ecoMAX if you backfed 4, the on/off switch on the boiler would not function. I consider the on/off switch being bypassed as a potentially more serious issue than the clock losing power when you are on hols.

The Glowworm Vaillant 4 series is made in Britain and does not have an on/off switch (too expensive, no doubt) and therefore there is no reason why term 4 cannot be used for switched live.
 

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