Specifications

20
LP- 276 REV. 9.4.14
Table 8 – Mod Con Heat Exchanger Pressure Drop
G. HIGH VELOCITY CIRCULATOR PUMP
Every VWH system requires special attention to pump size in order to overcome the pressure drop through the boiler and its related
piping. All circulators installed on the VWH system must be designed for a potable water system.
Water temperature above 140
o
F requires the circulator pump to run continuously and water hardness between 5 and 7 grains.
Hardness above 7 grains will damage the heat exchanger and shorten the service life of the boiler.
H. WATER CHEMISTRY
Chemical imbalance of your water can cause severe damage to your water heater and associated equipment, and may also affect
efficiency. You may have to have your water quality professionally analyzed to determine whether you need to install a water softener.
It is important that the water chemistry on both the domestic hot water and central heating sides are checked before installing the
heater, as water quality will affect the reliability of the system.
Outlined below are those water quality parameters which need to be met in order for the system to operate efficiently for many years.
Failure of a heat exchanger due to lime scale build-up on the heating surface, low pH or other imbalance IS NOT covered by
the warranty.
Water Hardness
Water hardness is mainly due to the presence of calcium and magnesium salts dissolved in the water. The concentration of these salts
is expressed in mg/L, ppm or grains per gallon, as a measure of relative hardness of water. Grains per gallon is the common reference
measurement used in the U.S. 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 when the water is heated and cause accelerated lime and scale accumulation on a heat transfer surface.
If the hardness of the water exceeds the maximum level of 7 grains per gallon, 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.