35
110332-02 - 6/22
PHTM II
Installation, Operating & Service Instructions
3. Fill valve (required)
A. Either a manual or automatic fill valve may
be used, but a manual valve is preferred
because it eliminates unmonitored additions
of make-up water to the system.
B. Ideal location for fill valve is at expansion
tank.
C. If using antifreeze with automatic fill valve,
it is recommended to install a water meter
to monitor make-up water. Antifreeze
concentration will decrease as make-up water
is added. If using antifreeze, local codes often
require a backflow preventer or disconnect
from city water.
10
Heating System Piping
(continued)
4. Expansion tank (required)
A. If this boiler is replacing an existing boiler with
no other changes in system, old expansion
tank can generally be reused.
B. If expansion tank must be replaced, consult
expansion tank manufacturer's literature for
proper sizing.
C. If using antifreeze, account for additional
expansion of glycol solution when sizing
an expansion tank. In a typical residential
heating system, a glycol mixture has an
expansion rate of 1.2 times that of water
alone, therefore a tank for an anti-freeze
system should be at least 1.2 times
greater in size. Antifreeze should be stainless
steel compatible.
Figure 10-2: System Curve w/ 50 equivalent ft. of piping
0
5
10
15
20
25
30
0
2
4
6
8
10
12
14
16
Pr
es
sure
Drop
(F
ee
t o
f Hea
d)
Flow Rate (GPM)
Pressure Drop vs. Flow
120
150/180
