lp-181 Rev. 3.3.15
4
Figure 1 - Recommended Service Clearances
B. Water Chemistry Requirements
Chemical imbalance of the water supply may affect efficiency
and cause severe damage to the storage tank and associated
equipment. HTP recommends having water quality
professionally analyzed to determine whether it is necessary to
install a water softener. It is important that the water chemistry
be checked before installing the storage tank, as water quality
will affect the reliability of the system. In addition, operating
temperatures above 135
o
F will further accelerate the build-up of
lime scale and may shorten the service life of the storage tank.
Failure of a storage tank due to lime scale build-up, low pH, or
other chemical imbalance IS NOT covered by the warranty.
Outlined below are water quality parameters that need to be
met in order for the system to operate efficiently for many
years.
Water Hardness
Water hardness is mainly due to the presence of calcium and
magnesium salts dissolved in water. The concentration of these
salts is expressed in mg/L, ppm, or grains per gallon as a measure
of relative water hardness. Grains per gallon is the common
reference used in the US water heater industry. Hardness
expressed as mg/L or ppm may be divided by 17.1 to convert to
grains per gallon. Water may be classified as very soft, slightly
hard, moderately hard, or hard based on its hardness number.
The minerals in the water precipitate out as the water is heated
and cause accelerated lime scale accumulation on a heat transfer
surface. This lime scale build-up may result in premature failure
of the storage tank. Operating temperatures above 135
o
F will
further accelerate the build-up of lime scale and may shorten
the service life of the storage tank.
Water that is classified as hard and very hard must be softened
to avoid storage tank failure.
Part 3 - Piping
A. Plumbing
CLASSIFICATION
MG/L OR PPM
GRAINS/GAL
Soft
0 - 17.1
0 - 1
Slightly Hard
17.1 - 60
1 - 3.5
Moderately Hard
60 - 120
3.5 - 7
Hard
120 - 180
7 - 10.5
Very Hard
180 and over
10.5 and over
If the hardness of the water exceeds the maximum level of 7
grains per gallon, the water should be softened to a hardness
level no lower than 5 grains per gallon. Water softened as low
as 0 to 1 grain per gallon may be under-saturated with respect
to calcium carbonate, resulting in water that is aggressive and
corrosive.
pH of Water
pH is a measure of relative acidity, neutrality, or alkalinity.
Dissolved minerals and gases affect water pH. The pH scale
ranges from 0 to 14. Water with a pH of 7 is considered neutral.
Water with pH lower than 7 is considered acidic. water with a
pH higher than 7 is considered alkaline. A neutral pH (around
7) is desirable for most potable water applications.
Corrosion
damage and tank failures resulting from water pH levels
of lower than 6 or higher than 8 ARE NOT covered by
warranty.
The ideal pH range for water used in a storage tank
is 7.2 to 7.8.
Total Dissolved Solids
Total Dissolved Solids (TDS) is a measurement of all minerals
and solids dissolved in a water sample. The concentration of
TDS is usually expressed in parts per million (ppm).
Water with a high TDS concentration will greatly accelerate
lime and scale formation in the hot water system. Most high
TDS concentrations precipitate out of the water when heated.
This can generate a scale accumulation that will greatly reduce
the service life of the storage tank.
The manufacturer of the storage tank has no control over
water quality, especially TDS levels in your system. TDS in
excess of 2000 ppm will accelerate lime and scale formation
on the element or the heat exchanger. Storage tank failure
due to TDS in excess of 2000 ppm IS NOT covered by warranty.
Failure of a storage tank due to lime scale build-up IS NOT
covered by warranty.
Hardness:
7 grains
Chloride levels:
100 ppm
pH levels:
6 - 8
TDS:
2000 ppm
Sodium:
20 mG/L
C. Optional Equipment
Below is a list of optional equipment available from HTP:
• Aquastat Cover with BX and Line Cord (GL-50 Models
Only) Part # GL-KT1
• Aquastat Cover with BX, Line Cord, and Bronze Pump
(GL-50 Models Only) Part # GL-KT2
It is mandatory that all plumbing be done in accordance
with federal, local, and state plumbing codes and practices.
