The red and blue pipes are almost certainly Whale pipes and available from many chandleries e.g. https://www.asap-supplies.com/products/whale-mdpe-tube-in-red-15mm-x-12mm-10m-w-wx7154
See attached for the Whale catalogue.
As an aside, beware of using these pipes close to the calorifier as they are not certified to that temperature and will gradually develop a hard to find pin-hole leak. I had an interesting discussion with a Whale Rep once criticising boat builders for not using the right fitting between the calorifier and the plastic pipe.
- This reply was modified 2 weeks, 1 day ago by Bob Garrett.