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Harsco Industrial, Patterson-Kelley Technical Service 1.877.728.5351
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HARSCO Industrial, Patterson-Kelley boilers are designed to be incorporated into any multi-metal hydronic
heating system. All multi-metal hydronic systems require that attention be paid to water treatment. The chemical
additives for any multi-metal system must be specifically formulated for use with all the various metals used in
that system.
Any closed, hydronic heating systems should include a meter, to monitor water addition to the recirculating loop, and
a filter, pursuant to ASHRAE Standard 189.1 and the AWT Handbook. Water added to a closed hydronic system
should not exceed more than 10% of the system volume per year and meter readings should be recorded, at least
monthly, to ensure system losses are minimized and corrective actions shall be taken when needed.
Treatment programs for multi-metal systems should meet or exceed the following generally accepted best
practices water quality guidelines:
1. Proper cleaning and surface preparation must be completed prior to system start-up.
2. pH must be maintained in a range that is appropriate for the metals contained in the system (see chart below).
3. Total Alkalinity between 100-500 ppm as CaCO3.
4. Filtration as per industry best practices.
5. Total suspended solids below 10 ppm.
6. Corrosion inhibiting compounds to protect metals at or below:
a. Aluminum <0.25 MPY
b. Copper <0.1 MPY, soluble copper <0.25 ppm
c. Steel <3.0 MPY According to ASTM D 2688
7. Addition of strong acids is not recommended.
8. Maintain Chlorides < 125 mg/l.
Prior to initiating any treatment program, a water sample of the proposed fill water should be sampled for
analysis. Once filled and bled of air, a pH neutral, industrial cleaner for use in multi-metal systems should
be used to clean the entire hydronic system. Samples of the system water with cleaner should be taken and
analyzed to ensure proper cleaner strength. Once cleaned, the system should be flushed with fresh (fill) water
until the system water is within 100 micro Siemens in conductivity of the fresh water. When flushing is complete,
a treatment program that is designed for use in that multi-metal system, after consideration of the metals it
contains, must be used. Treatment programs should also comply with the standard water quality guidelines listed
above.
multi-metal systems with Aluminum
multi-metal systems with
stainless steel
multi-metal systems with Copper
Proper surface cleaning required
Proper surface cleaning required
Proper surface cleaning required
pH maintained between 6.0-8.5*
pH maintained between 6.6-8.5*¤
pH range may vary *`**
Total Alkalinity 100-500 ppm as CaCO3
Total Alkalinity 100-500 ppm as CaCO3
Total Alkalinity 100-500 ppm as
CaCO3
Best Practices Filtration
Best Practices Filtration
Best Practices Filtration
Suspended solids below 10 ppm
Suspended solids below 10 ppm
Suspended solids below 10 ppm
Corrosion rates below:
0.1 MPY copper
3.0 MPY steel
0.25 MPY aluminum
Corrosion rates below:
0.1 MPY copper
3.0 MPY steel
0.1 MPY sst ^
Corrosion rates below:
0.1 MPY copper
3.0 MPY steel
Max. MPY other metals
Addition of strong acid not recommended Addition of strong acid not recommended Addition of strong acid not
recommended
When freeze protection is required, automotive grade glycols are not recommended and decomposition products should be monitored and maintained
below concentrations that present corrosive conditions. For existing boiler water systems, additional requirements and operational conditions may be
required to mitigate pre-existing conditions.
* Other system components may have more restrictive ranges.
¤ Per Industry SST Heat Exchanger Manufacturers.
** Copper has a broad range of acceptable pH and the other metallic components may require a tighter range.
^ Per ASHRAE/AIA Presentation # 6017 2012 Winter Conference.
c
2013 Harsco Corporation. All Rights Reserved Rev: 10/15/2013
