Central Heating Boiler..

[GazSuttonUK]

Hi, we have a Ferroli Optima 1001 Boiler..
The central heating is working fine, but the hot water will only work with the central heating on...and then it could be cool or boiling hot...
Any idea's where I should be looking for the fault?
Many thanks for any help.

 

[45yearsagasman]

Don't know the model first hand, but your boiler probably has a dual pass heat exchanger (no separate plate exch) and the more likely cause of your problem will be a flow switch of some sort, probably on the cold feed inlet.

 

[ianmcd]

Your boiler does indeed have a twin pass heat exchanger and the signal to the boiler that a DHW tap is running is done by the flow meter it is right at the bottom of the boiler in the center, follow the cold water inlet pipe and you will see it, possibly just blocked but may need replaced also check the DHW thermistor it is on the DHW outlet pipe next to the Air pressure switch

 

[GazSuttonUK]

Thanks both of you, very much appreciated..

 

[GazSuttonUK]

Your boiler does indeed have a twin pass heat exchanger and the signal to the boiler that a DHW tap is running is done by the flow meter it is right at the bottom of the boiler in the center, follow the cold water inlet pipe and you will see it, possibly just blocked but may need replaced also check the DHW thermistor it is on the DHW outlet pipe next to the Air pressure switch

Thanks for help, when you say the "cold water inlet pipe and you will see it, possibly just blocked"....is it just a case of removing it and cleaning/unblocking?
Cheers.

 

[ianmcd]

yes isolate the cold water inlet and open a hot tap till the water stops running, place a bowl or basin below the flow meter then remove it , its not hard to do, there should be a filter in there to stop any debris getting in but these are some times removed