8
Thermann Owner's Guide
Heat Pump Water Heaters
Draining The Cylinder
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Warning Injury
Hot water can be expelled during draining.
Close the shut-off valve in the cold water supply.
Fully open the hot taps at all draw-off points.
The cylinder is drained via the cold water inlet line. Open the drain valve. If no drain valve was installed, undo the
fitting on the cold water supply of the appliance. Residual water remains in the lower part of the cylinder.
ON THE SYSTEM
Material Losses
If the hot water unit is not used for two or more weeks, an amount of highly flammable hydrogen gas may
accumulate in the water tank. To dissipate this gas safely, it is recommended that a hot tap be turned on
for several minutes or until discharge of gas ceases. Use a sink, basin or bath outlet, but not a dishwasher,
clothes washer or other appliance. During this procedure, there must be no smoking, open flame or any
electrical appliance operating nearby. If hydrogen is discharged through the tap, it will probably make an
unusual sound as with air escaping.
Safety Valve
This valve opens when the water pressure exceeds the preset value of 0.7 MPa thereby relieving the pressure. It
is adjusted so that no water will be expelled when heating is switched OFF. Should it continue to drip excessively,
either the valve seat has become contaminated, the water pressure is too high or the pressure reducing valve has
become faulty.
Regular Valve Maintenance
Safety requires that valves are regularly checked for perfect function.
Regularly vent the safety valve until a full stream of water flows from it. Close the safety valve after checking.
How quickly limescale builds up depends on the local water quality.
As your local tradesperson is familiar with your local water quality, let them determine the timing of this check.
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