What make/ model do members recommend for a “master control valve””
I do not have one at this time and periodically consider one. To answer your question, I would personally use the same as what I am currently using for all of the other zones. I do realize that older systems may have a smattering of makes and models, which I do not. I personally do not get valves from the big box stores. The last time I did, they were subpar on quality.
Thank you. I just installed my Flo meter and this was next on my list.