Wiring Salus IT500 Thermostat - Combi Boiler

[davidbasic]

Hi There,

I'm hoping you can help me. I want to replace my T6360b Honeywell Thermostat with a Digital SALUS IT500.

My current thermostat is a Honeywell T6360B here is a pic of the connections:

I dont know why the yellow and green wire is connected to the first screw on the left. Is that the neutral? because according to the manual
(I found here http://www.honeywelluk.com/documents/All/pdf/1008.pdf)
it should go to screw #2

I guess the first question is:
- Is this a volt-free thermostat? It would appear that it is not based on the pdf above.
- How do i know if the wire green and yellow is a neutral?

Here are the diagrams for the iT500 thermostat. http://www.salus-controls.com/system-diagrams/

I believe the correct diagram to follow would be B. 230V Switching - Combination Boiler, can anyone confirm?

Let me know if you need more info

Thanks heaps.

 

[EFLImpudence]

I dont know why the yellow and green wire is connected to the first screw on the left. Is that the neutral? because according to the manual
it should go to screw #2

This does not bode well for your electrical future.
Green and Yellow is EARTH, as is the symbol at its connection.

You do not have a Neutral.
Your new thermostat will need one so you cannot put it there.

I guess the first question is:
- Is this a volt-free thermostat? It would appear that it is not based on the pdf above.

It is although it is a misleading term.

- How do i know if the wire green and yellow is a neutral?

Because it NEVER is.

I believe the correct diagram to follow would be B. 230V Switching - Combination Boiler, can anyone confirm?

Depends on the boiler.

 

[stem]

The Honeywell is a mechanically operated switch. To improve its accuracy, provision is made for a neutral connection to operate a small accelerator (heater) inside the thermostat. The neutral should be connected to terminal 2. You don't have a neutral connected, so whilst the thermostat will work, it will not be as accurate as it would be if it had the neutral.

The green and yellow wire is connected to the earth terminal. This is probably correct. However, it can only be truly an earth if the wire is connected to an earth at the other end. It probably is, but without seeing it I can't say for certain.

So basically your thermostat is wired as:

Earth terminal - Green / Yellow Wire
Terminal 1 Live supply - Brown Wire
Terminal 2 Neutral - Not used
Terminal 3 Switched Live - Blue wire (it should really have a brown sleeve to show that a neutral wire is being used as a live, so that it's not mistaken for a neutral)

So the bottom line is, if your new thermostat requires a neutral connection, you cannot use the existing wiring.

 

[EFLImpudence]

That is the old thermostat, stem.

The new one is the Salus.

 

[eveares]

I dont know why the yellow and green wire is connected to the first screw on the left. Is that the neutral?

Don't mean to be harsh, but if you really can't tell that the yellow and green sleeved wire is going to the earth terminal what is an essential safety feature , then you should not be contemplating replacing the thermostat your self!!


For your existing thermostat; terminal #1 is the common (Line), terminal #2 is the compensator (Neutral), terminal #3 is the Call for Heat (Switched line / NO when temp above set point), terminal #4 is the Call for Cooling (Switched line / NC when temp above set point)

Also, what looks like black wire tucked in the top right corner may be a neutral, but there is no way to tell or prove that from the photo.

- Is this a volt-free thermostat? It would appear that it is not based on the pdf above.

It can be wired either way as it's a mechanical thermostat, although it would not be as accurate as the compensator would not work. Yours is all most certainly wired to the 230v mains, albeit lacking the compensator being connected via a neutral to terminal 2.

I believe the correct diagram to follow would be B. 230V Switching - Combination Boiler, can anyone confirm?

Depends if You have a combi boiler and only want it for the central heating, or want to use it with a conventional boiler for both Hot water and Central Heating in what case you would need to swap it with your existing programmer.

Yes, diagram B is correct for a typical combi boiler; your brown wire would go to L, Blue wire would go to NO, Neutral to N, and a jumper link between L and COM. Should you not have neutral, you will have to install the IT500 at the boilers end using 3C+CPC where you have access to a neutral.

How do i know if the wire green and yellow is a neutral?

Again, you really should get a qualified electrician in to do the work for you for your own safety! Green and Yellow is always Earth!

Hope this has helped , and sorry if I seem abrupt ; just don't want you compromising your or anyone's else's own safety!


Regards: Elliott

 

[ban-all-sheds]

I dont know why the yellow and green wire is connected to the first screw on the left.

Because it's an earth conductor, and terminal #1 is the earth terminal.

Is that the neutral?

No, it's the earth.

because according to the manual
(I found here http://www.honeywelluk.com/documents/All/pdf/1008.pdf)
it should go to screw #2

1. It shouldn't.
2. That's not what the manual says.

Here are the diagrams for the iT500 thermostat. http://www.salus-controls.com/system-diagrams/

I believe the correct diagram to follow would be B. 230V Switching - Combination Boiler, can anyone confirm?

1. You can only do that if you have a neutral at the thermostat position, and that's unknown.
2. If your boiler wants volt-free switching and you poke 230V into it you might destroy the control board.

This does not bode well for your electrical future.

Don't mean to be harsh, but if you really can't tell that the yellow and green sleeved wire is going to the earth terminal what is an essential safety feature , then you should not be contemplating replacing the thermostat your self!!
.
.
.
you really should get a qualified electrician in to do the work for you for your own safety!

 

[stem]

That is the old thermostat, stem.

The new one is the Salus.

I know that because there is a photo of the existing Honeywell. I was just advising him what the existing wiring was and specifically that there was no neutral installed. But you beat me to saying that anyway.

 

[EFLImpudence]

That is the old thermostat, stem.The new one is the Salus.

I know that because there is a photo of the existing Honeywell. I was just advising him what the existing wiring was and specifically that there was no neutral installed. But you beat me to saying that anyway.

Ah, sorry.

 

[davidbasic]

OK guys, sorry for asking stupid questions and thank you for your replies

Now that I have overcome my embarrassment here is what I got.

(Ps. I will not touch anything until I know what I need to do... therefore the reason for my post here ) Thanks a lot. Asking questions is the only way to learn.

FYI it is a combi boiler Valiant Pro 24

So I noticed in the old thermostat there is a black cable that appears to be on its own so I opened the boiler and found that the black cable at the boiler end is also not connected to anything so potentially this could be the neutral I need to get me going???

here is the Electric board layout

And here is a pic of section X1 from diagram above. As you can see the black cable is not connected to anything and I'm wondering if I can use it to connect the neutral that I need.

 

[EFLImpudence]

That seems lucky. Brown, Blue and Black is unusual. Is there also a Grey cut off?

Anyway, to keep it right
Switch off power,
From the thermostat cable:
Connect the Blue to Neutral after removing tape - with the other Blue.
Connect the Brown to L - with the other Brown
Connect Black to RT after sleeving it with Brown.

Then at the thermostat:
Put Green/Yellow in a separate piece of connector block and position safely as it is not needed.
Then, as the picture:
Brown to L with link to Com.
Blue to N
Black to NO after sleeving with Brown.

 

[ban-all-sheds]

That seems lucky.

Indeed. Once it is proven that the black at the boiler is the same black as the one at the thermostat.

 

[davidbasic]

[QUOTE="EFLImpudence, post: 3466576, member: 144975]
Black to NO after sleeving with Brown.[/QUOTE]

What do you mean by "after sleeving with brown"

 

[davidbasic]

[QUOTE="EFLImpudence, post: 3466576, member: 144975]
Black to NO after sleeving with Brown.[/QUOTE]

What do you mean by "after sleeving with brown"

 

[EFLImpudence]

It is now a live conductor therefore you must identify it with either a brown sleeve or brown tape, as was the blue in the boiler.

 

[stem]

Something a bit fishy here. You have an existing thermostat that by rights should have a neutral connection in order to function properly. It doesn't, yet it appears that there is a spare core in the existing cable that could have been utilised so easily, yet wasn't. Hmm.. I wonder why.