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Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
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31
Water Heating Piping
1. Use only the pipe sizes shown and a pump meeting the listed specifications in the following tables:
*NOTE: Individual Appliance Piping pressure drop used in the tables is based on 20 feet of straight pipe, 6 elbows, 2 tees, 2
full port ball valves and 2 unions.
2. The city cold water supply to the water heating system should be connected between the heater outlet and the storage tank or
the storage tank directly. This will help minimize unnecessary short cycling due to small hot water draws. Higher efficiency can
be obtained through use of our optional CWIS™ - Cold Water Injection System in any Armstrong Hot Water, Inc. Storage Tank.
3. Isolation valves should be installed on each heater and on the cold and hot water system connections.
Upon completion of piping, fill and properly purge of all air. Open all valves and start circulating pump. Consult Armstrong Hot Water,
Inc. for specific piping diagrams for your application.
NOTE: Minimum pump selection is based on piping sizes shown above and water hardness not to exceed 15 grains per gallon
and total maximum equivalent piping length of 60 feet.
Table 5.2 Water Heater Piping
Model
GPM
∆
P*
(LPM)
Design
∆
T
Minimum Manifold Pipe Size
Single
Double
Triple
Quad
HW 299
16.5 @ 22.9’
52.5-7m
35.3º F
19.6º C
1.5”
2”
2”
2.5”
HW 399
26.4 @ 20.3’
100-6m
29.4º F
16.3º C
2”
2”
2.5”
3”
HW 599
39.6 @ 23.6’
150-7m
30.9º F
17.1º C
2”
2.5”
3”
4”
*Water heater and piping as described above.
Figure 5.2 - Heater Piping
R
Re
effe
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en
nc
ce
e d
diim
me
en
ns
siio
on
ns
s a
ar
re
e ±
± 1
10
0%
%
A
Allll d
diim
me
en
ns
siio
on
ns
s a
ar
re
e ±
± 1
1"
"
MM/DD/YY
MM/DD/YY
1/2"=1'
Custom
Dwg No.
Customer / Job name:
Scale:
Description:
Date:
Drawn/
Revised by:
Checked/
Apv. by:
Revision:
Description:
Date:
Drawn/
Revised by:
Checked/
Apv. by:
Revision:
(1)HWD 299 to HET 220
AJT
05/24/10
XX
City Water
Connection
Piping - continued
