We're just putting in the UFH pipes and I'm trying to work out the best position for the manifold but the best position for it is smaller than the alternative location. We have 5 zones but 9 loops (so 18 pipes in total) so I was assuming that we'd need an 18 port UFH manifold but the biggest ones I've seen are 12 port. Basically, what I want to know is what would be the length of the manifold plus pump, valves etc to suit our requirements?

A 12 port manifold will accept 24 pipes  You need a 9 port manifold. 

For example only

 

Edited to add :

You can buy unions which will allow you to separate the blender and pump from the rails if space is tight. I did this on a previous install where I needed the whole thing to fit in a corner. Rails went to the left, and then unions took the rail flow and return into the corner and across the back wall where I then reconnected to the pump set. Bingo. 

It's one port per loop as they are "stacked" on top of each other. 

 

A quick measure of mine it's about 40mm per port and then around 220mm for the pump etc so you would be around 600mm for a 9 port

The below is a picture of our 8 port set up the total width is around 850mm

 

 

Brill. Thanks all  

@worldwidewebs Andrew, you've got an MBC frame so you must do your basic heat calcs.  I doubt that you will be losing more than a couple of kW on your heating days -- unless you have large areas of glass.   9 loops = ~ 800-900m of pipe or ~150m².  If you reckon on 7W/Km², then you will generate ~1 kW/K across the slab, so if your slab is much hotter than a few degrees more than room temperature then you will soon get too hot.  Therefore:

1. I would really question the sense of having 5 zones from a control PoV.
2. You will need to do a mix down in your UFH.

Read Jeremy Harris's blog posts on his adventures in designing his UFH slab system: pure gold-dust.

Yes - 5 zones just for control. And you're pretty much bang on - we have 800m of pipe!

 

It will be the only heat source we have and I'm not anticipating turning it on much (the PHPP calcs showed a pretty minimal heat load demand), but having it and not using it is better than not having it and needing it! I'm still struggling to get my head around not needing much heating though, even though I've been in a few well insulated houses. 

 

I do need to sort out the cooling soon too!!!!