sunvic room stat problem

[wobblymike]

hi grateful for a bit of help
my daughter in law has recently had a new combi boiler fitted when she showed me the installation i was surprised to see that the original anaogue sunvic thermostat remained in place. we decided to replace it with a danfoss tp5000 digital thermostat. very helpfully i discovered a step by step guide on one of these forums for just this job. my first task was to identify the wire which was permanently live and which was switched live. however all the wires in the stat, red, blue and green have zero volts on them even though the stat calls for heat when the appropriate temperature is switched. all wires measure zero volts under all circumstances i.e both when boiler is fired up or idle. i guess i am missimg something any help welcome

 

[snowhead]

Permanent Live may not be 240v on the new boiler.
It could be low volts D.c.

 

[wobblymike]

thank you i'll kook into that

 

[wobblymike]

following snowheads response I have had a look at this again with not too much joy. The boiler concerned is a Saunier duval f24e with the current room stat as stated being an old sunvic mechanical. I have downloaded the manual for the boiler and as far as I can see the stat operates off 230v so I am no further forward. Any further thoughts welcome.

 

[Mark.W]

Faulty programmer maybe?! Does the heating work?!

 

[snowhead]

Does the new boiler currently work with the old Stat?

 

[wobblymike]

snowhead that is the strange thing when the stat clicks on the boiler fires up and the heating works but no ac volts measurable on any of the 3 wires - what i have not done yet is measure for dc volts or measure on resistance to see if a circuit makes when stat clicks. i guess thats next

 

[SYKRAPS]

So it is probably a volt free setup and you are probably lucky that the stat did not send 230v to the boiler, many boilers work with volt free arrangements

 

[goldie]

Exactly.as stated above. Jst an open/closed contact. check the connections inside the boiler aswell to make sure. you can purchase drayton or danfoss digi stats similar to the tp 5000 that you already have. they come with batteries to energise the display