Hey, This seems simple but I'm driving myself crazy on the web. Our Hunter owner's manual shows plumbing laid out as being 1/2 Whale plumbing. The push fittings are marked as being 15mm (Whale fittings as well). This leads me to ask if perhaps the plumbing is 15mm, not 1/2 inch, or that it's close enough in size to not matter (i.e. the 15mm fitting fit fine on the 1/2 in plumbing). I'd like to know if I can just use some 1/2 inch PEX for a few changes. We're removing the HW tank due to a leak and I've bypassed the plumbing for now, but would like to make it a little neater. Anyone gone through this with their plumbing? 2nd question: I'll be removing the coolant lines from the engine (2MG20F) and just plugging them with stainless steel pipe plugs. Anyone know the specs on those holes/threads or where to find them? Cheers.