Hi,
Seems well thought out, but I think you need an adapter to attach the mainline to the manifold, and an endcap. Rough calculations put the prices you list in your post at about $36. Adding the additional parts brings it to $44. I build 1 inch PVC manifolds for about $7 in parts.
You didn't mention why replacement is necessary, but another solution may work.
I rarely replace a valvebody, usually from freeze damage. I have had to replace gaskets, solenoids,and bonnets before. I usually unscrew the top of the offending valve, and replace the whole top. No pipe problems, and a lot less time ( and less money than replacing the whole manifold)
I build my manifolds with male adapters on each side of the fFPT valves. I leave enough room between the valves, do I can turn the valve if I need to re[place it. To keep 3 valves in one box, I place them close enough to be able to be screwed on and off, withthe top (Bonnet and solenoid)removed . Then I place the bonnet back on.
I had a customer with a 3 valve setup at the absolute low point of his yard. Replaced the valves twice, so used slip joints on the down valve side, which made unscrewing the cracked valve body much easier. No cutting and glueing. Finally convinced him to move the valves but a drain in its place.
Moral, fix it right, maintain it, and no more repair is necessary. So if your new manifold will do that for you, Go For It; Otherwise hopefully my suggestions wil accomplish that for you.
Hope that helps, let us know how it goes.
Jeff
Jeff,
Thank you for the reply and all of your suggestions! There are a couple of reasons why I wanted to replace the manifold... First, I have to relocate the manifold because I am adding an extension to the house where the manifold is located. Yes, I suppose I could just cut it at the mainline and repurpose it, but what I didn't mention is that I am also replacing all the valves as well. The reason for that is that I can no longer get replacement parts for my existing 30 year old valves! Also, the new valves seem a tad wider than the old ones, and I don't think there would have been enough room as the existing valves were already very close together. So I was hoping to start over again with something that is designed better and makes removing a single valve a snap. My only concerns with using this approach are the potential for these fittings/unions leaking and that if I do have to replace a valve that the fittings/unions will be easy to realign and tighten. I guess we'll see...
There is no doubt that building this from PVC would be much cheaper and probably less prone to leaks, but I'm going to give this a try with the manifold kit parts. You are also correct about needing an endcap and a mainline adapter. I've got those now. Thanks again for the reply and I will reply again once this is built! The parts are on order...