Install Instructions

Viega IM-PFMB 1007
7
a
s well as eliminating interference
between fixtures. Often each fixture
can be fed with smaller diameter
tubing which is easier and faster
to install.
Design Factors For Installing
A Parallel System
• Water Heater Placement
This should be as close as possible to
the MANABLOC to minimize extra
water from being stored in the larger
hot water supply lines between the
MANABLOC and water heater.
The longer this hot water supply line
is the greater the volume of water
requiring purging through the faucet
before hot water is available. This
causes greater water waste and
longer hot water delivery times.
• Proper Water Distribution Line
Sizing To Each Fixture
This is crucial for over all system
performance. If you over size a
distribution line to a fixture (1/2" PEX
line supplying a sink instead of a 3/8"
PEX line) you are essentially doubling
the volume of water being stored in
that line. This can take roughly twice
as long to purge compared to
properly sizing the line.
The fixture is what dictates water flow
(federally mandated, governed by
code). The tubing simply applies a
friction lost dictated by its size and
length. Therefore, as long as you do
not under size a distribution line or run
it excessive distances (60 feet or
greater), the system will perform
properly maintaining sufficient
pressure and flow.
• The Length Of A Distribution Line
Run To Each Fixture
This can drastically affect the
performance of a MANABLOC system,
the longer the line is the more water
being stored within it, and therefore,
the longer it will take to purge it out
before hot water can reach the fixture.
T
his is just as important as properly
sizing each distribution line. The
MANABLOC should be located
somewhat central to your fixture
groups keeping within 60 feet or less
of each fixture.
If you can not accomplish this with
one MANABLOC you may need to
use two MANABLOCs, locating one at
each end of the home to split the
distribution line distance between
them (see section 4.8 for use of
multiple MANABLOCs).
2.2.2 Branch and Main
Systems
This method of plumbing is
commonly referred to as a
conventional plumbing system, or
branch and tee systems, which uses
copper/rigid tubing with tee and
elbow fittings.
This system uses a large diameter
"main" supply line (minimum 3/4") for
both hot and cold water supplies that
runs throughout a structure to or near
each fixture group with smaller
"branch" lines teeing off the main to
supply each fixture.
While this system can reduce the
amount of tubing used it requires
more fittings to be used, which can
increase installation time and cost.
D
esign Factors For Installing
Branch And Main Systems
•
Design the layout as condensed
as possible
Keep the main hot supply line close to
the fixture groups with the branch
lines shorter than 6 feet. This will help
provide hot water in a reasonable
amount of time with a more tolerable
amount of wasted water.
The limiting factor for installers to
accomplish an optimal design is how
spread out the fixture groups are
within the structure.
If the builder did not put any thought
into keeping the fixture groups
condensed, a branch and main
system will have terrible hot water
delivery times with substantial
water waste.
If you have a floor plan that
incorporates stacked or back to back
fixture groups then a branch and main
system can be an effective alternative
to a parallel system.
One disadvantage to these systems is
they store excess amounts of water in
the large main lines, therefore the
further away the fixture is, the longer
the main supply line must be to reach
it, purging all stored water out before
hot water reaches the fixture.
Another trait these systems suffer from
is noticeable pressure drop during
multiple fixture use. When you turn on
multiple fixtures you are increasing the
water flow (load) within the main line,
causing higher friction loss equal to
pressure loss at the point of use. This
is why you notice a drop in pressure
(and potentially a temperature
change) in your shower when a toilet
is flushed.
2.2.3 Combination Systems
A combination system uses multiple
manifolds combined with a
branch and main type supply system.
These systems use small manifolds
Branch Installation.