Ariston MicroGenus 23 MFFI Hot Water query

Hi all
I have the above system, I know (old and not the best) however it has served me well, considering it was already fitted in the property when I moved in.
Earlier this year I had the main and secondary heat exchangers replaced by British Gas (long story - they didn’t need changing but as they were BG they insisted, however back then the problem still persisted so I didn’t get charged for it; it was a faulty expansion vessel in the end!)
Anyhow I currently have a problem where the hot water downstairs or upstairs is tepid even when the dial is cranked up to max.
Heating works fine.
I have narrowed it down to the 3-way valve (can hear radiators ticking when water is drawn), however I have a query.
Do I need to drain the system down to remove it? This is so I have inhibiter at hand (added 2 bottles of Fernox F1 in October so will be gutted if I have to)
Also, does the lead on it come off easily? Do I just pull it off or is there a technique to it?
That’s it really.
Would appreciate the guidance as the lack of “hot” water is making for a quick bath at the moment

 

check you cylinder stat first before you change the three port valve

 

Which one is this please?
Do you have a link so I can read into it?
It’s not the temperature probe is it?

 

It's a combi boiler. Given the questions, replacing a diverter is likely to be beyond you...call someone in.

 

Anyone in the brummy area fancy doing it

 

sorry read this post wrong when you said three way valve I thought you had a system boiler, my bad

 

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