Potterton Thermostat PRT100.ST

[lives1]

Hi,

I am trying to replace an existing potterton thermostat with a newer looking version. However as I am a complete novice I am not sue which wires to connect and in what order.

I have attached a link to some pictures of the existing wired unit, the new unit which gives options of 4,4,2 & 1 connections, and also the wiring instructions.

//www.diynot.com/network/lives1/albums/

Hopefully someone out there can give me some guidance.

Thanks in advance

 

[stem]

Well the new PRT 100 thermostat is easy, the diagram in your album shows it as follows:

The live from the programmer/timeswitch = 1
The switched live for the motorised valve or boiler = 2
Neutral = Either of the terminals marked 4

So now the tricky bit is determining what the existing wires are. Usually they are:

Live from programmer = Red
The switched live for the motorised valve or boiler = Yellow
Neutral = Blue

However this can't be guaranteed, as it depends on which colours the installer decided to use when he wired it. Is there are circuit diagram for the existing thermostat? Often it's printed inside the cover you've removed.

Failing that, if you're competent with a multimeter, disconnect all 3 and with the programmer set to 'on' use the multimeter to find the live and neutral, the remaining wire will be the switched live.

 

[lives1]

Thanks for this - there is a picture of the existing wiring on the link in my original post. Wasnt sure how to get photos into main body of text.

Would be grateful if you could have a quick look and let me know.

Cheers

 

[lives1]

Sorry misread the last post. The inside of the existing thermostat does have a diagram which says:

4 N
2 H
1 TL

I take it this means something to you?

 

[stem]

Yes I've seen the wiring, but it depends on what is connected to the other end, normally the colours are as I've said but there's nothing to stop the installer swapping them around.

If you tell me the make & model of the existing stat I may have the necessary information. I can't see clearly but are the terminals marked

....... 1
4,2,5

With 5 not used?

Edit - Just seen your last post

That's good
TL = Thermostat live
H= Heating Load (or switched live)
N = Neutral


So finally

Old Stat-Colour-New Stat
TL(1)-Red cable-1
H-(2)Yellow cable-2
N-(4)Blue cable-4

No surprises there then!

 

[lives1]

On the existing unit which is a potterton PRT100 also - I am only replacing as it looks dated and discoloured!!!

Red is going to 1 (TL)
Yellow is going to 2 (H)
Blue is going to 4 (N)

There is not a 5 mentioned on the existing thermo diagram!!!

So if I understand on the new one this means:

Red is Live (TL) and goes to 1
Blue is Neutral (N) and goes to either of the two 4's
Yellow is switched live (H) and goes to 2

What about the earth?

 

[stem]

Yep you got it. I was looking at the numbers stamped on your existing thermostat in your photo below. As best as I can make out, the new thermostat uses the same terminal numbers that they are connected to now.

Untitled

• stem
• 23 Feb 2010
• 1

If the new thermostat is double insulated, (it will have a symbol of a square inside another square) there is no requirement for an earth, so insulate the earth it and tuck it out of the way.

 

[lives1]

just to confirm I found a little picture of the square inside the square as you said so no need for earth. Brilliant

Won't actually be doing the upgrade until weekend so will have some light when supply turned off. Fingers xd - thanks for the great advice.

 

[masif]

Dear DIYers/Experts,

I was just looking to replace my potterton Thermostat (as mentioned in the earlier posts) in this thread, with the new one available here.
http://www.ebay.co.uk/itm/16A-Digit...ostat-Temperature-Control-Sensor/261589411485

Is this doable job and if possible what would be the possible wiring in this case?

If not, would i be able to put a Nest Thermostat on top of this?

Cheers,

 

[Echo the husky]

That ebay thermostat is for underfloor heating applications and is not a suitable replacement for a standard room stat. A nest stat can be fitted in place of it, though will require some wiring alterations.