Onix Tubing Installation Manual

Watts Radiant: Onix Installation Manual page 63
Typical Nomograph
Nomographs are generated by
RadiantWorks as design aids for con-
tractors and engineers for optimizing
radiant floor heating designs. Each
nomograph is customized for a specif-
ic room or zone within a project. The
following is a brief explanation of how
to interpret a nomograph.
Note: The accompanying slab nomo-
graph is customized and should not
be generalized to frame floors, other
floor coverings, other Onix sizes or
differing indoor air temperatures.
On the upper left hand corner of the
nomograph you will see the system
design parameters. In this case, the
nomograph is for a slab with 1/4’’ tile
where the desired indoor temperature
is 70¡F, the outdoor temperature is 0¡,
the project is at an altitude of 2000 ft.
and 3/8’’ Onix is being installed.
The left vertical axis displays the radi-
ant floor heat output intensity, as
expressed in BTU/h/sq.ft. of radiant
floor surface.
The right vertical axis displays the
average floor surface temperature. The
actual floor surface temperature will
vary –1¡F relative to the measurement
location; that being taken over a cir-
cuit or between two circuits. In general
a system will need to be designed so
the average floor surface temperature
is 85¡F or below. Higher surface tem-
peratures can be used if allowed by
ASHRAE guidelines and the floor
covering manufacturer.
The top axis on the nomograph
reflects the total heat loss through the
edges and underneath the radiant floor.
As the radiant floor heat loss increas-
es, the mean water temperature in the
floor also increases. This heat loss is
expressed as BTU/h/sq.ft. of radiant
floor. It is calculated for each project
by RadiantWorks based upon the actu-
al design parameters which include
floor insulation, floor covering and
overall system design.
The bottom horizontal axis shows the
average, or mean, water temperature
flowing through the radiant circuits.
This is not the entering water tempera-
ture. For example, if the entering
water temperature is 108¡F and the
exiting temperature is 88¡F then the
mean temperature is 98¡F, the average
of the two.
Watts Heatway Nomograph © for Kitchen Area
Slab application with 3/8" Onix
Watts Radiant Nomograph © for Breakfast / Kitchen Area
Slab Application 3/8" Onix
Required Heat Load Line
Tube Spacing
Room’s Actual
Conditions
Radiant Floor Heat Output Intensity [Btu/h sq.ft.]
50
45
40
35
30
25
20
15
10
5
0
90
88
85
83
80
77
74
71
67
63
58
Effective Floor Surface Temperature [°F]
60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220
Mean Water Temperature [°F]
98
6oc 9oc 12oc 15oc 18oc
Total Floor R-Value: 0.6
Indoor Design Temp: 68[°F]
Outdoor Design Temp: 0[°F]
Maximum Allowable
Floor Surface Temperature
EXAMPLE ONLY
Appendix