Ravenheat CSI 85 no DHW unless CH on.

[Louisme2]

I have a problem with a Ravenheat CSI 85 (18 months old) which will only give DHW when the CH is on.

If turned to DHW mode the boiler will not fire.

I have checked diverter valve which is operating microswitch ok when hot water tap is running and also checked that microswitch works and leads back to circuit board are all ok too.

There is allot of corrosion(water dripping) around the DHW thermistor - could this stop the boiler firing up?

Also, this might be a separate problem but sometimes the heating comes on without being asked for but only for a little bit, the radiators get luke warm then boiler stops - i have had a look at the diaphram but it looks ok(i think?)

Any ideas summers coming and having to turn the heating on to warm the hot water is driving me mad!

 

[ChrisR]

SOunds like the microswitch is stuck in hw position.
Clean/test/change the sensor and stop it leaking!

 

[Louisme2]

Thanks ChrisR going to order a HW Sensor today - i just didn't know what the next step was as i have tested the microswitch&wires back to PCB with a multimeter and they are all ok. When i run the hot tap the microswitch is pressed and it goes straight off as soon as i stop the tap.

Could the HW Sensor also be causing the heating to come on?

 

[ChrisR]

No, it would only make the hw come on if the microswitch was made.
Are you saying the ch is coming on when it shouldn't?

 

[Louisme2]

yes, sometimes during the day or night you can hear the pump running and occasionally it fires up but never for long (the radiators get luke warm) this happens even when the timer is off - this only started happening in the winter and i thought it could have been some sort of frost control but now i don't think my boiler has that.

The CH started to come on occasionally (outside of when i programmed it), then more often until now when the HW only works if the CH is turned on - i am not sure if this is two separate faults or one that has got worse and worse!

Sorry if this is a bit confusing but if i switch CH on or it comes on via the timer then everything works as it should.

 

[Agile]

Has this leaking sensor dropped water onto the DHW demand switches?

Obviously ( to me ) if that has happened then the boiler will come on for CH ( although its actually coming on for DHW !!! ).

Tony

 

[Louisme2]

Hi Tony,

Thanks for the advice that sounds like it would make sense! I am going to replace the DHW sensor and check(again)/replace the DHW demand switch&wires - will post the results!

thanks,

Louis

 

[Louisme2]

Hi Just installed a new temp sensor and i now have hot water! Hurray!

Thanks very much for both your help (going to keep my fingers crossed about the heating not coming on on its own any more..).

Louis