Saunier Duval Thelia 623 have hot water but no heating !

[Agile]

As I recall there is no official middle position for the summer/winter switch.

If its doing something unusual in between the two official positions then it indicates the switch may be faulty.

I have never encountered any problem with that switch before though.

Tony

 

[Ant]

oops

 

[Ant]

Sounds like it could be the diaphragm in the water pressure switch that is faulty. A friend of mine installed several of these boilers in a development and almost all had this problem at one time or another (including mine). I can't recall if when mine went it affected the CH or hot water, but it may be worth a look. Part is fairly cheap and not too difficult to fit with reasonable skills. Good luck!

 

[Agile]

If the diaphragm has failed then it will prevent the boiler responding to a demand for hot water.

I would not consider it as easy to fit ( as a result of the multiple leaks which occur if you even look at one of these boilers ).

Tony