With no water tank to heat up, combi boilers can provide an unlimited supply of hot water on demand no waiting time! On top of that, you need to be in receipt of. Anthony and jake came out and unclogged my drain! did a great job , fast , and knowledgeable! We'll automatically renew your plan so that you can continue to enjoy the benefits of your boiler care product. Dump the hot water down the drain so that it can melt away some of that grime and any hardened grease if this.