Table of Contents
Advertisement
Water quality
In direct water heating appliances, the water flows directly through the heat exchanger of the water
heater. Because all the time fresh water, containing dissolved minerals, is heated, scaling may occur. To
prevent this, water quality must meet a number of standards. The water must meet the specifications be-
low:
Water temperature max. = 85°C
Maximum allowed water hardness should not exceed 196 PPM CaCO
flow is enlarged, a water hardness up to 250 PPM (14 °dH or 17.5 °Clark) is acceptable.
TDS (total dissolved solids) may not exceed 450 PPM
Water hardness and TDS together should not exceed 450 PPM
The pH value of the water may not be under 6.5 and not above 7.5 (measured cold)
If water hardness is too high a water softening system is necessary.
If TDS alone or the combined value is higher than the abovementioned, the water should be heated by
means of an indirect water heating appliance.
Minimum water hardness = 70 PPM or 70 mg/L CaCO
Minimum TDS = 100 PPM
Water under these minimum values normally has a pH value which is aggressive and corrosive.
If these values are exceeded a water treatment specialist should be consulted. Water Softeners and Water
Conditioners may be considered, but whichever method is selected, it should be suitable for installation
with Direct Gas-fired Water Heaters. A maintenance regime will also be required for such systems.
The formation of lime scale or other solids can cause a blockage within the heat exchanger, which in
turn may cause premature failure. Such instances are not regarded as defects in manufacture and will
not be covered under the product warranty.
Flush the system with fresh water
When a water heater is installed in a new system or an existing installation the system must be cleaned before
the water heater will be used. The system should then be drained and thoroughly flushed with clean water to
remove any debris. The water of the water heater and heating circuit should be free of any particles, debris and
pollution.
De-Air sequence.
The De-Air sequence is a safety function starting at every power ON and is used to remove the air from the heat-
exchanger. The De-Air sequence does not start after a general reset (as the locking error reset or 24 hours reset)
The display will show 'dAir' indicating that the controller is performing the De-Air sequence to purge the heat
exchanger of air, by sequencing the water heater pump OFF and ON. The installer/technician can cancel the De-
Air sequence by pressing a specific key-button combination from the display.
The De-Air sequence consists of cycles.
▪
The general pump cycles in an ON/OFF pattern of 10 second periods. This is repeated for De-Air_Repeti-
tion_Cnt times.
When the flow is too low, or the pressure sensor is in error, the De-Air sequence will be suspended until the wa-
ter pressure / sensor pressure is stable again.
The following scheme below shows the behavior of the general pump during one whole cycle of De-Air sequence
with a De-Air_Repetition_Cnt set to 2:
ON
Pump
OFF
(11 °dH or 14 °Clark). If the water-
3
(4 °dH or 5 °Clark)
3
E93.1804.014
29
Advertisement
Table of Contents
