Adding a thermostat to an existing back boiler pump system?

[adamrhoades]

Hi there,

I currently have a back boiler system, pump fed, with a digital timer that controls both the heating and water.

I have TRV's in every room except the kitchen, and currently no room thermostat.

I would like to add a room stat, a wired one will suffice, to have the heating cut out when the house reaches the desired temp, but am unsure how such a device connects to the system.

My existing wiring loom is very messy, could someone please describe where the thermostat should connect, between certain components, across them, before?

http://farm3.static.flickr.com/2670/4107787376_ff6fb623df_o.jpg

That black link looks very hopeful?

Any and all vice gratefully accepted!

Thanks in advance!

 

[kevplumb]

y plan

• kevplumb
• 19 Sep 2009
• 22

y plan wiring

might help

 

[bengasman]

Are you competent working on 230V? As it is indeed a mess, and not quite according to the "official" diagram, you can expect anything. As nothing is marked and colour coding not consistent, you will have to verify every wire to makes sure it is all safe.

 

[adamrhoades]

That diagram helps greatly, and yes quite competent thank you

As I wish to wire my new thermostat up and place it nearby my time controller, and I can now see that the thermostat will require a neutral feed and essentially connects after the timed heating circuit......

Would it be possible to wire into the back of the time controller, taking the neutral from here and placing the switched output from the thermostat and applying it to the HTG Pin on the timer? using a junction box of course.

I am assuming that the room thermostat will be a closed circuit below the target temp and an open one above?

Also, are all room thermostats 3 wire connections, or are some two? how might this effect the installation?

Many thanks again in advance, its starting to become a little clearer to me now!

Adam

 

[jackthom]

If you are OK working with electrics take a look at the back of the digital programmer and identify the Central Heating ON wire.

See if you can then find where this enters the junction box in the photograph.

That's the one to break and insert the room thermostat in series.


Edit: if there's room in the programmer backplate to do it safely that sounds OK. A new wire to the Heating ON terminal would go to the COMMON on the room thermostat. The return wire from the thermostat carrying Switched Live would connect to the original wire that was removed in the programmer.

A battery operated 2-terminal room thermostat wouldn't need a Neutral connection.