Sign up to get the latest promotions, new releases and freebies! Shewfelt's plumbing & heating ltd. Are you looking for trusted boiler repair and installation services in London? If pressure has dropped once, it will drop again. There may come a time when the cost of having an old, faulty or inefficient boiler prompts the question: should i get a new boiler? Wax pm, young a caustics in: marx ja, hockberger rs, walls rm, et al,.