I recently had to add 3 rads to a system for a half job done by some muppets. They installed 3 rads, and left it at that. The poor customer was then quoted £1'000 to have 3 more rads installed by the same people. Luckily i got to speak to her before she confirmed the work with these other guys and i added thh 3 rads for her for 1/3 of the price.