Manifold head loss, sketchy info, does it mater?

Robert_H

A new system we are working on has two manifolds. The system manifold is a Viega and the one for the radiant ceiling is a Roth. For head loss calculations I'm looking for the Cv data. Both have a supply and return bodies with Isolation ball valves on the input, balancing/shut off valves on each return tap and flowmeters/adjusters on the supply taps.



The Viega tech documents provide data for the flow meters and balancing valves. But not data for the ball valves.



The Roth is a new “NP” Manifold System of which there is no online documentation and the documentation I received in the box seemed like it was for a different system. I contacted Tech support and was emailed a copy of the data sheets.

The return side balancing valves list Cv at 2.77 at full open but the Cv values for the Isolation ball valves and the flow meter/adjusters are blank, as if they are still working on that...

Everything I have studied says the head loss for these components is part of the overall circuit head loss, which is critical for proper pump selection.



Are the Ball valves on these manifolds of a flow characteristic that the head loss is  negligible?

Robert_H

correction

Viega does provide the Cv data  for the flowmeters and the balancing valves on the Technical Data Sheets.  I'm not sure how I overlooked that yesterday. My apologies for asking an unnecessary question.