Product Overview

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103859-12 - 8/19
MPO-IQ
Installation & Service Manual
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 piping.
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.
WARNING
Do not operate boiler below minimum volumetric
flow rates.
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 4.
b. Maintain a constant boiler pressure of 12 PSI.
Boiler Model No. Flow Rate (Gal / Min)
MPO-IQ84B 4.5
MPO-IQ115B 6.0
MPO-IQ147B 8.0
MPO-IQ189B 10.0
MPO-IQ231B 12.0
B. CONNECT SYSTEM SUPPLY AND RETURN PIPING
TO BOILER. See Figures 10 and 11. Also, consult
Residential Hydronic Heating Installation and Design
I=B=R Guide.
1. If this boiler is used in connection with refrigeration
systems, the boiler must be installed so that the
chilled medium is piped in parallel with the heating
boiler using appropriate valves to prevent the chilled
medium from entering the boiler. Also, consult
Residential Hydronic Heating Installation and Design
I=B=R Guide.
2. If this boiler is connected to heating coils located
in air handling units where they may be exposed to
refrigerated air, the boiler piping must be equipped
with flow control valves to prevent gravity circulation
of boiler water during the operation of the cooling
system.
3. If an indirect water heater is used, priority zoning
can be used. Do not use priority zoning for Hydro-
Air Systems. Refer to the Indirect Water Heater
Installation, Operating, and Service Instructions for
additional information.
4. The MPO-IQ is designed to withstand thermal shock
from return water temperatures as low as 100°F,
but prolonged return temperatures of below 135°F
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 10 and
11 in order to regulate water flow for maintenance
of higher boiler water temperature.
NOTICE Failure to pipe boiler as specified in this manual may result in excessive system noise.
Table 4: Minimum Flow Rate
3 Water Boiler Piping
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