Spread the cost from â£9.99 per month. Asap plumbing installed a 40 gallon water heater for us i was very pleased with the service everything went well. Our qualified gas safe engineers will be there as soon as possible to fix your glow-worm boiler if you have a problem, feel free to book a service online or call us on. Specialist in domestic plumbing. Great boiler since september 2011 touchwood, no issues as of yet. Very natural.