Install Instructions
18
EMP
Installation & Service Manual
109529-03 - 11/19
 A.  EVALUATE THE EXISTING WATER 
SYSTEM.
  Design a piping system and install boiler which 
will prevent oxygen contamination of boiler water 
and frequent water additions.
1.  There are many possible causes of oxygen 
contamination such as:
a. Addition of excessive make-up water as a 
result of system leaks.
b. Absorption through open tanks and fittings.
c. Oxygen permeable materials in the 
distribution system.
 2. In order to insure long product life, oxygen 
sources must be eliminated. This can 
be accomplished by taking the following 
measures:
a. Repairing system leaks to eliminate the 
need for addition of make-up water.
b. Eliminating open tanks from the system.
c. Eliminating and/or repairing fittings which 
allow oxygen absorption.
d. Use of non-permeable materials in the 
distribution system.
e. Isolating the boiler from the system water by 
installing a heat exchanger.
  WARNING
 System supply and return piping must be 
connected to correct boiler manifolds. 
 U. S. Boiler Company recommends sizing the 
system circulator to supply sufficient flow (GPM) 
to allow a 20°F temperature differential in the 
system. When sizing the system circulator, the 
most restrictive single zone should be used to 
determine maximum pressure drop.
CAUTION
 Maintain minimum ½ inch clearance from hot 
water piping to combustible materials.
3.  In order to insure long product life, operate boiler 
at appropriate flow rate to minimize areas of 
overheating
.
a.  Design system to ensure that the flow is above 
the limit called for in Table 5.
b.  Maintain a constant boiler pressure of 12 PSI.
  WARNING
 Do not operate boiler below minimum volumetric 
flow rates.
B.  CONNECT SYSTEM SUPPLY AND RETURN 
PIPING TO BOILER. See Figures 9A and 9B.  
Also, consult I=B=R Installation and Piping Guides. 
1
.  If boiler is used with an Alliance™ SL Indirect Fired 
Domestic Water Heater, install the Alliance™ SL as 
a seperate heating zone. Refer to the Allaince™ SL 
Installation, Operating, and Service Instructions, 
for additional information.
2. 
The EMP is designed to withstand thermal shock 
from return water temperatures as low as 100ºF, 
but prolonged return temperatures of below 135ºF 
can cause excessive flue gas condensation and 
damage the boiler and/or venting system.
  Use a boiler bypass if the boiler is to be operated 
in a system which has a large volume or excessive 
radiation where low boiler water temperatures 
may be encountered (i.e. converted gravity 
circulation system, etc.) The bypass should be 
the same size as the supply and return lines 
with valves located in the bypass and return 
line as illustrated in Figures 9A and 9B in order 
to regulate water flow for maintenance of higher 
boiler water temperature.
3.  If it is required to perform a long term pressure 
test to the hydronic system, the boiler should 
first be isolated to avoid pressure loss due to the 
escape of trapped air.
  To perform a long term pressure test including 
the boiler, ALL trapped air must first be removed 
from the boiler.
  A loss of pressure during such a test, with no 
visible water leakage, is an indication that the 
boiler contained trapped air.
Boiler Model No. Flow Rate (Gal / Min)
EMP84E 4.5
EMP115E 4.5
EMP140E 8.0
EMP182E 10.0
EMP224E 12.0
Table 4: Minimum Flow Rate
3 Water Boiler Piping 
  NOTICE:  Failure to pipe boiler as specified in this 
manual may result in excessive system noise.
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