Kil•block - drain unblocker x 4 - an extremely effective product. Only use copper or cpvc pipe for t&p discharge. Chas are as health & safety accreditation scheme for the construction industry. Making sure pipes have proper slope and the job is done right! We pride ourselves on offering a unique local services 24 hours a day 7 days a week. The £50 callout excess does not apply to new boilers in warranty only other items you have on cover external.