Inspection, Maintenance & Care For The Appliance - Dražice OKC 300 NTR/1MPa Operation And Installation Manual

2.7 INSPECTION, MAINTENANCE & CARE FOR THE APPLIANCE
During the heating process the water that increases its volume during the heating must
visibly drip off the safety valve outlet (in non-pressurised connection this water drips off the
combination faucet valve). In full heating (about 74°C) the volumetric water gain is approx.
3.5 % of the tank capacity. The function of the safety valve has to be checked regularly. If the
safety valve control knob is lifted or turned to the "Control" position, the water must flow
out easily, without any obstacles, from the safety valve element to the outfall line. In
common operation, such a check needs to be carried out at least once a month, and after
each heater shutdown that exceeds 5 days.
Caution! In doing so, the cold water supply pipe and the connection fitting of the tank may
get heated! If the hot water heater does not work, or if hot water is not withdrawn, no
water shall drip off the safety valve. If water drips, then the water pressure in the supply
piping is either too high (if higher than 5.5 bars, a pressure control valve has to be fitted), or
the safety valve is defective. Please call a specialised plumber immediately!
If water contains too many minerals, an expert has to come to remove the scale that forms
inside the tank, as well as free sediments. This has to be performed after one or two years of
operation. The cleaning is carried out through the hole in the flange – dismantle the flange
lid and clean the tank. A new sealing has to be used for re-fitting. Since the inside of the
heater has special enamel, which must not get in contact with the scale removing agent – do
not work with a lime pump. Remove the lime layer with a timber and suck it off, or wipe it off
with a clout. After that, the appliance must be rinsed thoroughly and the heating process is
checked the same as during the initial putting in operation. Do not use any abrasive cleaning
agents (such as liquid sand, chemicals - acid, alkaline) or dye thinners (such as cellulose
thinner, trichlor, and the like) to clean the outer shell of the heater. For cleaning use a wet
clout and add a few drops of liquid cleaning agent for household applications. Repetitive
water heating causes limestone sediment on both the tank walls and chiefly the flange lid.
The sedimentation depends on the hardness of water heated, its temperature, and amount
of hot water consumed.
We recommend checking and cleaning the tank from scale and eventual replacement of
the anode rod after two years of operation. The anode life is theoretically calculated for two
years of operation; however, it changes with water hardness and chemical composition in
the place of use. Based on such an inspection, the next term of anode rod exchange may be
determined. If the anode is only blocked with sediments clean its surface and, if used up,
mount a new one. Have the company in charge of service affairs clean and exchange the
anode. When draining water from the heater, the combination faucet valve for hot water
must be open, preventing occurrence of under-pressure in the heater tank which would stop
water from draining.
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