New hot water cylinder install, programmer problem

[m550344]

Have recently installed a new thermal store hot water cylinder. I connected the cylinder thermostat connection as per the old cylinder thermostat to the new cylinder thermostat but now have a problem with the Potterton Programmer. The programmer is ignoring on\off programmed times and is basically firing up the boiler whenever the cylinder reaches the set temperture - so basically always on. The thermostat appears to be functioning OK in that when the temperture is reached it will switch the boiler off.
I have had plumbers in to look at the problem and they have been unable to work out why the programmer is ignoring the timed settings and will always respond to the cylinder thermostat. They changed the programmer with a replacement like for like programmer and problem still exists. I could replace the cylinder thermostat but it appears to be working as it should. Any ideas?

 

[migoplumber]

its a new install, so likely the wiring isnt correct.
the cylinder stat will should only call for heat after the timer has said so.

check the wiring. or post a drawing of it.

 

[m550344]

Thanks. Have new thermostat coming as have bench tested the thermostat and it all seems to work as it it should. But then when setting the programmer, boiler kicks in again when programmer is set for off......

 

[david williams]

seems like its been wired with themostat controling programer should be otherway round

 

[m550344]

Problem resolved, thermostat wiring fault