Boiler shutting down when energising S/L?

[Richww]

Hi - I’ve upgraded old stat for new Nest stat and heat link - all working as it should, except that when switched live is energised via 3-port valve (orange) or cylinder stat, it seems to switch the boiler off?

Boiler is Ideal Icos HE15
3-port Danfoss HSA3
Cylinder stat Drayton HTS3

All wired up as per Nest wiring diagram

Have checked S/L to boiler, getting 240v when called for, so functioning as expected.

However, I’m getting 240v FROM the boiler on S/L connector (having disconnected from 3-port) - is this correct?

As above, when all connected, boiler sits on standby - when 240v is sent to S/L, it’s as if boiler powers down.

Separate pump is connected to same terminals and operates as expected.

Any thoughts would be appreciated!

 

[ianmcd]

live is energised via 3-port valve (orange) or cylinder stat, it seems to switch the boiler off?

Post pics of your wiring, the cyl stat should not be connected the the S/L of the boiler it send power to the mid position valve and the orange wire from the valve tells the boiler to fire, not the cyl stat

 

[CBW]

Have you changed anything else?

 

[Richww]

Thank you for your replies…

I took a new permanent and switched live feed to boiler and all up and running - happy days!