Onix Tubing Installation Manual

page 60 Watts Radiant: Onix Installation Manual
Manifold Set Up
There are two ways fluid can flow
through a manifold pair: 1) Direct and
2) Reverse Return. Both are dictated
by how the Onix is attached to the
manifolds.
Direct is the easiest to install, and in
most cases, the easiest to follow. The
down side to this method is balancing.
A Direct set up will tend to require
more post-fill balancing. This is due to
the simple fact that the last circuit on
the manifold will see a potentially
higher pressure drop than the first cir-
cuit. This higher pressure drop will
equate to less flow and less heat deliv-
ery from that circuit. To fix this prob-
lem, it is important to have mini-ball
valves installed on one or both mani-
folds.
Reverse Return is the preferred
approach. It eliminates almost all need
for post-fill balancing. For this set up,
the first circuit on the supply manifold
will be the last circuit off the return
manifold. Each circuit sees the same
manifold length, creating an even pres-
sure drop across each circuit.
Both set ups depend on the simple fact
that each circuit is the same length,
give or take 10%.
If a Long Manifold is installed, it is
imperative to set the manifold up in a
Reverse Return fashion. This is essen-
tial when the manifold spans the
length of the zone.
Supply and return manifolds are
installed along the length of the zone,
perpendicular to the floor joists. To
make Onix connections simpler, we
recommend running a third copper line
so the supply manifold is being sup-
plied hot water at one end of the mani-
fold array. The return manifold should
then be discharging cooler water at the
opposite end of the manifold array, as
illustrated.
If each joist space is relatively long, it
may prove beneficial to run only one
circuit for each joist space. A more
common installation is to use one cir-
cuit to supply the heat to several joist
bays - drilling holes through the joists
as necessary. However, never use both
approaches in the same zone unless
Return
rn
Man
Man
ifold
fold
Supply Manifold
Fluid Flow
Fluid Flow
Frame Floor: Long Manifold
Flow
Flow
Flow
Capped End
Capped End
Supply Manifold
Return Manifold
Long manifolds are installed perpendicular to the floor joists. To ensure balanced
flow through each circuit, a reverse return method is recommended. A reverse
return manifold requires a third copper line to be installed. This extra line allows
each circuit to “see” the same total manifold length, thus creating a balanced
system.
Flow
Flow
Flow
Capped End
Capped End
Supply Manifold
Return Manifold
Appendix