To achieve 4 pipe control and weather compensation you would need the integral diverter valve, part no 7 738 112 913
Approx cost of £80-£100
Worcester Bosch – 4 Pipe System
Disclaimer: Information on this website is provided for informational purpose therefore we cannot accept liability for subsequent problems. All repair tasks should be carried out by qualified trades people. We may also receive commission payments when you are taken to external websites and complete purchases from third party sellers, once you leave our site, we cannot be held liable for your purchases.