help with thermostat?

[andyfer]

hi guys and gals?

i have a small issue!

im trying to change my old thermostat.

old is a satchwell tlx 2259, new is a siemens raa20.

i have three wires on the old,

yellow to pin 1
brown to pin 3
blue to pin 4

(whoever wired it in the first place has used a three core flex)

so has anyone any idea what pins those cores get wired to on a siemens raa20?

thanks in advance for any help recieved..

Andy

 

[spraggo]

Connect Brown to L on RAA
Connect Yellow to Y1 on RAA
Blue not required so insulate and isolate

 

[andyfer]

thanks for the fast reply.

have done that, it puts a demand in, but the boiler does not fire up? turn the tap on and it does?

any ideas?

 

[DP]

Blue not required so insulate and isolate

MAKE SAFE.

Is the CH switched on at the timer? else noting will happen unless the timer wiring also adjusted to suit.

 

[andyfer]

Blue not required so insulate and isolate

MAKE SAFE.

Is the CH switched on at the timer? else noting will happen unless the timer wiring also adjusted to suit.

Mmm,

well the timer is always on, and we get heating via turning the thermo up!

so are you saying i have to change wiring in the timer aswel?

 

[ChrisOxford]

well the timer is always on, and we get heating via turning the thermo up!

Which thermostat are we talking about? Presumably the old one? Otherwise, I'm confused.

 

[DP]

Three wires that terminated on your old stat were 1] neutral which should now have been taped up and not used, 2] live and 3] switched live that goes back to the boiler (or whatever) to get the appliance going.


Check stat wiring. Terminal L will have 240 on it all the time. Y1 terminal will have 240 on it when higher temperature is selected.

 

[andyfer]

yes thats correct......

wiring is done like that.

now what happens is when you turn the stat up, you can hear the boiler revieve a demand for heating but the boiler does not fire!

i put the old back and it works?? so havnt blown it up, lol.

 

[ChrisOxford]

...you can hear the boiler recieve a demand for heating...

What can you hear? A relay clicking? If so, in the stat, in the boiler, where?

If you remove the stat and link brown to yellow (with a connector block or whatever), does the heating come on?

 

[andyfer]

...you can hear the boiler recieve a demand for heating...

What can you hear? A relay clicking? If so, in the stat, in the boiler, where?

If you remove the stat and link brown to yellow (with a connector block or whatever), does the heating come on?

in the boiler, turn the stat, hear the boiler relay click! but the boiler does not fire up.

 

[ChrisOxford]

That doesn't seem right. It should be on or off, no halfway state is possible.

But don't forget that there's often an electronically-timed delay between CH demand occurring and the boiler actually firing up, especially if the CH has been on very recently. Try waiting a couple of minutes.

Are you absolutely sure you're hearing a click in the boiler, rather than a mechanical click from the new stat? This type of stat will click whether it's wired correctly or not.

If no joy, try linking out the wires as I described above and see what happens. Or you could connect the two wires to a lightswitch if you have an old one lying around.

Usual precautions about mains electricity apply, obviously!