Buderus 21 - Example: One-Pipe System Layout; Results: Output;ft Radiator Models; Solution: Step 1. Complete the Radiator Sizing Sheet

Applications manual
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Panel Radiator
Design Manual
Panel Radiator Design Manual | 12.2009 Technical specications are subject to change without prior notice
Example: One-Pipe System Layout
Design a one-pipe system for a second oor with
individual room temperature control:
Table 12
Description Heat Load Window
Size
Hook-up
Sequence
Bathroom 3,000 1x3 ft wide rst
Master Bedroom 9,000 2x4 ft wide second
Bedroom 2 6,000 1x3 ft wide third
Bedroom 3 4,000 1x3 ft wide fourth
Solution:
Step 1. Complete the Radiator Sizing Sheet to nd
minimum size radiator.
Step 2. Select control strategy and size piping and pump
using Table 7.
Step 3-4: See Table 13.
Step 5: Assume temperature drop (∆T) = 30°F (17°C),
maximum supply temperature = 180°F (82°C).
Step 6: Add all heat loads from row 2 and enter in Step 6.
Step 7: Compute ow rate in the one-pipe system in
GPM.
The ow rate can not exceed 2 GPM when
using diverter valves. Using a larger ∆T lowers
the GPM.
Step 8: Here we must compute the supply temperature
for each room. Start with the rst room and
compute each supply temperature step by step
as shown here.
Supply Temp (1) = 180°F (82°C)
Supply Temp (2) = 180 - 3000 / (500 x 1.47) = 176°F
(80°C)
Supply Temp (3) = 176 - 9000 / (500 x 1.47) = 164°F
(70°C)
Supply Temp (4) = 164 - 6000 / (500 x 1.47) = 156°F
(60°C)
Step 9: Now with each value computed in steps 4 and 8,
locate those values in Fig. 10. The output curve
located directly above that point identies the
minimum size radiator required. Use the 18°F
(10°C) ∆T curves if designing for a 20 to 30°F (11
to 17°C) temperature drop, use the 36°F (20°C)
∆T curves if designing for a 40°F (22°C) drop.
Results: Output/ft Radiator Models
Bedroom Supply Temp = 180°F (82°C) 1500 Btu/ft
#22 20”
M. Bedroom Supply Temp = 176°F (80°C) 1125 Btu/ft
#22 x 12
Bedroom #2 Supply Temp = 164°F (70°C) 2000 Btu/ft
#22 24”
Bedroom #3 Supply Temp = 156°F (60°C) 1333 Btu/ft
#22 24”
Use 5/8 ” PEX and diverter valves (or: 3/4” copper main
line with 3/4” x 3/4” x 1/2” monoow tees) with
thermostatic heads on all radiators for individual room
control. Place a thermostat in the bathroom or master
bedroom or run constant circulation. Use a Grundfos
UP15-42, a Taco 007, or equivalent pump with a
balancing valve to throttle the ow. Noise may otherwise
develop in the diverter valves.
Table 13
1 Select
room
sequence
Bathroom Master
Bedroom
Bedroom
2
Bedroom
3
2 Heat load
per room
3000 9000 6000 4000
3 Available
wall space
(ft)
2 8 3 3
4 Minimum
required
heat
load per
linear foot
(BTU/ft)
1500 1125 2000 1333
5 Minimum
Required
Heat Load
per linear
ft (BTU/ft)
ΔT = 30ºF
Supply temperature (room1)
=max supply temperature
= 180 ºF
6 Total
heat load
(BTU/ft)
Q = 3000 + 9000 + 6000 + 4000 = 22000 BTU/Hr
7 Total loop
GPM GPM = Q / 500 / ΔT = 22000 / 500 / 30 = 1.5 GPM
8 Supply
temp per
room
ΔT = Q / 500 / GPM
180 176 164 156
9 Possible
radiator
Models
and sizes