Room thermostat not working properly?

[Lowenrj]

Hi, first post so please forgive any etiquette breaks! My mother has a new condensing boiler and all is working fine.
However, her room thermostat appears to not be working as it should. Example being that if the dial is turned down at night to say 15 or 16 the heating stays off. When she gets up her house is cold, until she turns the thermostat to say 20 or 21, you hear the click and the heating comes on as it should. So unless its set to 20 or above the heating remains off. It appears to not work when it's turned down low, ie if she wants it on low at night. It's driving me and her crackers. Is there something wrong and is there anything I can do? Thanks in advance

 

[Roger Welton]

Its not been cold recently, circa 17-19 in my house, perhaps temp hasn't dropped sufficiently for thermostat to switch boiler on when set to 15/16.

 

[Lowenrj]

Yep I initially thought that but she has (just) told me its been the same for the past 3 winters!

 

[stevetheplumber]

there not expensive id just change it