Kj to boil a liter of water is rather more energy than you might think an. Strysen heating are turning 40 this year! we’d like to thank all of our customers and staff over the years for their continued support. A yearly service ensures that any warranty associated with your boiler is up to date and avoids the loss of manufacturer guarantees that could result in an unwelcome bill to repair. Now you’ve unblocked the drain, simply run some clear, fresh water.