MANIFOLDS RADIANT HEAT

I think that your last sentence

sums up my wish list.



Uponor, Caleffi, Heatway, Viega, all pretty decent. I prefer to specify the brass or stainless steel types and not the engineered thermo-plastic ones. Not for any reason of knowing something is wrong with them, just that metal is more permanent in the scheme of things and that is worth more than the cost difference to me.



Now, you did say that you were going to use a single circulator serving multiple manifolds, so that implies to me a wider distribution (versus a single large manifold and lots of long home-runs).



But I wanted to be sure that you grasp that these would all have the same temperature. Temperature is defined by a mixing valve and by default, a circulator to go with that.



So if all of your floors have the same flooring materials, spacing, depth, heat loss requirements, that is great.



But if you are serving different areas defined by carpet, wood, concrete, tile and different heat losses, you may need more than just manifolds, but manifolds, mixing valves and circulators for each type.



My rule of thumb is, if the requirements of each floor type need average water temperatures ten or more degrees apart, they would have their own mixing control. There are exceptions of course, but one needs to have a basis and point of departure.

Sounds like

you thought it out pretty well already.



This is obviously no small job you have here!  Sixteen manifolds?? At 60 mbh the building does not sound all that big and might be over-controlled, just asking. If the house has a heat load of 25 BTUH per SF, that is one manifold for every 150 SF. Even the dog will have one and so will the cat. Or do you mean 16 circuits?



As for manifold brands, I am not familiar with the two names you mentioned. May be good, may not be, I just do not know. Never heard of them.



My concern with odd brands is getting replacement parts and the quality of the metallurgy. For example, some brass, notably from overseas, has been known to dezincify, leaving a crumbling mass of demi-copper. Basically it is a breakdown of the alloy due to stray currents and other oxidizing factors.  So stainless to me is "safer". Brand names too, where you can get new hardware, replacement meters, valves, etc. Short money in the long run and a minor part of the cost.



Could you use copper manifolds and valves? Sure of course. Your tube layout wants each circuit to be within 10 percent of each other and I would also pipe them reverse-return (supply manifold fed from the left, return fed from the right, for example), to even out imbalance potential. The flow meters are nice when you want to fine-tune imbalanced circuits but also when you commission the entire system. If accurate, the sum of flow rates speaks to pump output. But a purchased manifold, with purge valves, isolation, temperature gauges, master isolation and drain valves, to me saves time and time is money. Even copper manifolds will have you making up an assembly.



You mentioned end switches to activate circulators. I do not know the type of flooring you have, the mass of the building and the overall control strategy, but radiant floors, even the lower mass ones, are much slower to respond than a baseboard or air system. Even low mass floors from a cold start might take half an hour to come to temperature. High mass floors could take a day or more. I can only suggest you re-think that, go with slab sensors and room sensors, constant flow and vary the temperature based on a departure from setpoint. More money on controls but the comfort is superior and constant without a wait. Circulator control puts an on-off mode in what is otherwise a modulating mode. Spikes over gentle waves. You want gentle waves.

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