When it comes to oil boilers, which? recommends the grant vortex pro the a-rated .% efficient model is available in different sizes according to dimensions of your home. Appointment arranged promptly turned up on the day as agreed and got the hot water working properly again excellent service! The longest % period available at the time of writing is months – see our. We install a wide variety of boilers to fit your home’s needs including burnham brand high-efficiency.