Filter
Top Products
6
Table 2 — Water Quality Guidelines
LEGEND
*Heat exchanger materials considered are copper, cupronickel,
304 SS (stainless steel), 316 SS, titanium.
†Closed recirculating system is identified by a closed pressurized
piping system.
**Recirculating open wells should observe the open recirculating
design considerations.
††If the concentration of these corrosives exceeds the maximum
allowable level, then the potential for serious corrosion problems
exists.
Sulfides in the water quickly oxidize when exposed to air, requir-
ing that no agitation occur as the sample is taken. Unless tested
immediately at the site, the sample will require stabilization with a
few drops of one Molar zinc acetate solution, allowing accurate
sulfide determination up to 24 hours after sampling. A low pH and
high alkalinity cause system problems, even when both values are
within ranges shown. The term pH refers to the acidity, basicity, or
neutrality of the water supply. Below 7.0, the water is considered
to be acidic. Above 7.0, water is considered to be basic. Neutral
water contains a pH of 7.0.
To convert ppm to grains per gallon, divide by 17. Hardness in
mg/l is equivalent to ppm.
UNIT LOAD PIPING — For applications with wide temper-
ature variation such as heating/cooling coils:
• Use piping materials that are rated for the maximum tem-
perature and pressure combination. This excludes PVC
for most heating applications.
• Ensure load water flow in high temperature heating
applications is at least 3.2 L/m per kW to improve perfor-
mance and reduce nuisance high pressure faults.
• DO NOT employ plastic to metal threaded joints.
• Utilize a pressure tank and air separator vent system to
equalize pressure and remove air.
• Employ an 800-micron particulate strainer in both load
and source plumbing to protect the plate heat exchanger.
Swimming Pool Hot Tub Applications
— Load heat ex-
changer should be isolated with secondary heat exchanger
constructed of anti-corrosion material in all chlorine/bromine
fluid applications.
Potable Water Applications
• Load coax material should always be vented double
walled for use in potable water systems.
• Ensure load water flow in high temperature heating
applications is at least 3.2 L/m per kW to improve perfor-
mance and reduce nuisance high pressure faults.
CONDITION
HX
MATERIAL*
CLOSED
RECIRCULATING†
OPEN LOOP AND RECIRCULATING WELL**
Scaling Potential — Primary Measurement
Above the given limits, scaling is likely to occur. Scaling indexes should be calculated using the limits below.
pH/Calcium
Hardness Method
All N/A pH < 7.5 and Ca Hardness, <100 ppm
Index Limits for Probable Scaling Situations (Operation outside these limits is not recommended.)
Scaling indexes should be calculated at 150 F for direct use and HWG applications, and at 90 F for indirect HX use. A monitoring plan should be
implemented.
Ryznar Stability Index
All N/A
6.0 - 7.5
If >7.5 minimize steel pipe use.
Langelier Saturation Index
All N/A
–0.5 to +0.5
If <–0.5 minimize steel pipe use.
Based upon 150 F HWG and direct well, 85 F indirect well HX.
Iron Fouling
Iron Fe
2+
(Ferrous)
(Bacterial Iron Potential) All N/A
<0.2 ppm (Ferrous)
If Fe
2+
(ferrous) >0.2 ppm with pH 6 - 8, O
2
<5 ppm check for
iron bacteria.
Iron Fouling
All N/A
<0.5 ppm of Oxygen
Above this level deposition will occur.
Corrosion Prevention††
pH
All
6 - 8.5
Monitor/treat as needed.
6 - 8.5
Minimize steel pipe below 7 and no open tanks with pH <8.
Hydrogen Sulfide (H
2
S)
All N/A
<0.5 ppm
At H
2
S>0.2 ppm, avoid use of copper and cupronickel piping of HXs.
Rotten egg smell appears at 0.5 ppm level.
Copper alloy (bronze or brass) cast components are okay to <0.5 ppm.
Ammonia Ion as Hydrox-
ide, Chloride, Nitrate and
Sulfate Compounds
All N/A
<0.5 ppm
Maximum Chloride Levels Maximum allowable at maximum water temperature.
50 F (10 C) 75 F (24 C) 100 F (38 C)
Copper N/A
<20 ppm NR NR
Cupronickel N/A <150 ppm NR NR
304 SS N/A <400 ppm <250 ppm <150 ppm
316 SS N/A <1000 ppm <550 ppm <375 ppm
Titanium N/A >1000 ppm >550 ppm >375 ppm
Erosion and Clogging
Particulate Size and
Erosion
All
<10 ppm of particles and
a maximum velocity of
6 fps.
Filtered for maximum
800 micron size.
<10 ppm (<1 ppm “sandfree” for reinjection) of particles and a maxi-
mum velocity of 6 fps. Filtered for maximum 800 micron size. Any par-
ticulate that is not removed can potentially clog components.
HWG— Hot Water Generator
HX — Heat Exchanger
N/A — Design Limits Not Applicable Consid-
ering Recirculating Potable Water
NR — Application Not Recommended
SS — Stainless Steel