Free Traffic Legal Advice

Hello Everyone,
I had a plumber fit a new heating system last year and now one of the joints he fitted has failed and caused a lot of damage. Although he has admitted using the incorrect type of fittings (against manufacturer’s instructions) he is denying responsibility – because he’s always done it that way. I have proof he used the wrong fittings and of him admitting it.
He wants me to claim off my house insurance, and they can contact his insurance company if hey want.
If I claim off my own house insurance, it will count against me and I will lose my no claims discount. Which means I will still be worse off.
Do I have any options other than small claims court?