MC2: 10/03/12 Page 85 of 90
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Water Quality
suitable aluminum safe propylene glycols available that can provide the same levels of burst, freeze and
corrosion inhibiting protection as traditional propylene glycols. Consult your local AERCO representative
for recommendations on glycol solutions. If a glycol solution is used as anti-freeze protection, a backflow
preventer must be installed upstream of the fill/makeup valve.
Only virgin glycol should be used for systems requiring freeze protection, and it must be treated with an
inhibitor compatible with the particular chemical treatment being used in the system. Note that glycol must
be changed from time to time due to its limited useful life.
13.1.5 Water Treatment Certification
When using chemical treatments in hydronic systems, it is necessary to ensure that the chosen treatment
is appropriate and certified by the manufacturer for such environments. The manufacturer should also
guarantee that the treatment, when applied according to the manufacturer’s recommendations, will not
cause harm to the boiler, pumps, piping, and other components of the hydronic boiler system.
13.2 Testing and Maintenance of Water Quality
Water in the installation should be checked, monitored, and treated for the following conditions and
characteristics:
• Hardness - High hardness of the available water is measured in grains of hardness and indicates the
quantity of minerals (mostly calcium and magnesium) which are dissolved in the water. Hardness
substantially contributes to the formation of scaling, which is highly undesirable. The total hardness
must be less than 200 ppm (11.7 grains/gallon)
• Artificial Softness – Do NOT use artificially softened water. Artificial softening agents generally use
salt, which creates a chloride water chemistry, a major contributor to the corrosion of the types of
metals used in hydronic systems. Elevated salt levels also contribute to higher conductivity levels,
another undesirable characteristic in hydronic systems.
• Chloride - Chlorides are salts resulting from the combination of the gas chlorine with a metal and are
instrumental in accelerating corrosion in the types of metals used in hydronic systems. Chlorides may
be introduced into the water naturally. Concentrations of chlorides in system water should be less
than 150 ppm.
• Conductivity – Dissolved metals and minerals increase the conductivity of water and indicate not
only the presence of undesired corrosive agents, but also contribute to the transfer and migration of
ions and charged particles in the water that contribute to fouling of sensors, valves, and other devices
used in the system. Additionally, high conductivity contributes to galvanic corrosion, in which one
metal will preferentially corrode when in contact with another type of metal, when both are in contact
with an electrolyte. Conductivity should be less than 3000 μS.
• pH - The pH, a measure of the acidic, neutrality, and alkalinity of the water, MUST always be within
6.5 and 8.0 for boilers using aluminum alloys, such as the Modulex boiler system.
• Oxygen - All precautions should be taken to avoid the formation and localization of oxygen in the
water of a heating system. Water that is low in minerals (soft water) absorbs oxygen much more
readily than mineralized (hard) water. For this reason it is necessary that in heating systems using
floor radiant heating, the plastic pipes used are impermeable to oxygen.
• Scale and Corrosion - The use of an inhibitor is advisable to treat feed and make-up water and to
protect heating systems against scale, corrosion and microbiologic growth. To prevent freezing, the
use of an anti-freezing agent together with the inhibitor is advisable. Qualified companies can also
provide boiler de-scaling.
• Total Solids - preferably less than 500 ppm, but a requirement of less than 1000 ppm
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