Ariston CLAS HE Evo

[Meguinness]

Hi guys
hope you can help , Ariston CLAS HE Evo......central heating working fine as it should, but when using the hot water taps in the sink and shower the temperature keeps going from hot to cold every few seconds continuously .
i can see the lines under the flame on the display going up and down (see video clip). error codes stored are 107 and 1p1 .
any ideas what could be the problem and what should i inspect ? pressure is between 1 and 1.5 bars.
thank you in advance

 

[Meguinness]

Anyone please? ta

 

[kidgreen61]

Your problem may be caused by several issues, I went to a similar fault yesterday caused by a faulty shower valkve which was allowing cold to water to crossover into the hot side.
I was fortunate in that the shower valve had iso valves fitted, I isolated the cold supply to the boiler but water still came out of hot taps, process of elimination led to to faulty shower.
You may need some pro help with this?

 

[CountryFan]

According to the manual both codes relate to insufficient circulation, so as above could be a few issues. Best left to a pro.