Mach® Water Chemistry - Harsco Industrial MACH C1500GG Installation & Owner's Manual

8.5 MACH® W
ATER
®
The MACH boiler uses an aluminum alloy that will withstand the acidic condensate (pH ~ 3.0 to 5.0) formed
when firing natural or LP gas under conditions which cause the flue gas to condense on the fire side of the heat
exchanger. However, the alloy is not resistant to highly alkaline (pH >9.0) environments, so care must be
exercised to assure that the water inside the heat exchanger remains in the neutral range (pH ~ 6.0 – 8.5).
Other metals, such as steel, cast iron or copper that are commonly found in hydronic heating systems are
reactive in neutral to acidic environments so water chemistry must include buffers and protectants that prevent
corrosion of these metals. In response to these needs, many chemical treatment manufacturers have devised
multi-metal treatments that protect aluminum, steel, iron and copper based metals.
The manufacturer of the chemical treatment system must certify that the treatment is intended for use in
hydronic systems that include cast aluminum boilers. Additionally, the manufacturer should guarantee
that the treatment system, when used in accordance with the manufacturer's instructions, will not
damage the boiler, piping, pumps, and terminal units and associated components of the hydronic
system.
The water quality requirements for the MACH
The pH must be between 6.0 and 8.5.
The total hardness must be less than 200 ppm (11.7 Gr/Gal)
The chloride must be less than 25 ppm
Total solids should be less than 500 ppm and must be less than 1000 ppm
Other contaminants should be less than 1 ppm
Conductivity must be less than 2400 μS
Do not use artificially softened water
The hydronic heating system must be a closed loop system. Free oxygen, in particular, can cause the formation
iron oxides (rust). Electrolytic action in the presence of oxygen causes the formation of magnetite in un-inhibited
water. When sludge (formed when calcium compounds, primarily CaCO3, are heated) is mixed with magnetite
and rust, a very hard scale will form. This scale significantly reduces system efficiencies and shortens the life
expectancy of the heating system. Thus, it is important to maintain a tight system to limit the introduction of
fresh water make up, which contains dissolved oxygen, minerals and other potential contaminants. A general
rule of thumb for any closed hydronic heating system is to limit makeup water to no more than 5% of the total
volume per year.
Flushing, Cleaning and Treating the System
When installing a new boiler, the piping system must be cleaned to prevent contaminants from upsetting water
chemistry. Before cleaning the system, the boiler must be isolated from the piping system to prevent
introduction of sludge and other contaminants into the boiler. Under no circumstances should the hydronic
system be flushed while the boiler is attached to the system. Debris or corrosion products may accumulate in
the boiler and plug the heat exchanger. The boiler must be disconnected from the system and a bypass
installed so that the chemical cleaning solution does not circulate through the boiler.
1. Thoroughly flush the system to remove as many contaminants as possible.
2. Fill the system with water, add the cleaning chemicals and circulate as per the chemical supplier's
instructions.
3. Drain and flush the system thoroughly until the system water TDS is within 10%of the make up water TDS.
4. Add the Multi-Metal protector/scale inhibitor to the system following the chemical supplier's instructions.
5. To be sure that the boiler is not air-bound, open the pressure-relief valve located at the rear of the boiler.
Leave the relief valve open until a steady flow of water is observed. Close the valve and finish filling the
system.
For systems requiring freeze protection, only virgin glycol should be used. The virgin glycol must be treated with
an inhibitor compatible with the chemical treatment system chosen. Note that glycol has a limited useful life and
must be changed periodically. Most of the manufacturers listed below offer glycol with their inhibitors premixed.
C
HEMISTRY
®
Boiler are as follows:
60
MACH® Gas-Fired Boiler