2 x Product description
14
BA ROTEX GSU - 09/2007
2.5 Storage tank
Important instructions for hydraulic integration
Observe the following instructions for hydraulic system integration of the ROTEX GasSolarUnit in order to avoid damage to
persons and property.
– Protection from scalding: When operating the ROTEX GasSolarUnit, especially when using the solar energy, the storage
tank temperature can exceed 60 °C. It is advisable therefore to take measures that prevent scalding (hot water mixing unit
such as VTA32 15 60 16) at the time of installation.
– Preventing flue gas escape: To prevent flue gas from escaping, the storage tank must be filled to overflow when starting
up the ROTEX GasSolarUnit.
– Corrosion protection : In some regions, supply companies provide aggressive drinking water, which by can cause corrosion
even to stainless steel. Ask your water company whether any corrosion problems are detected with the use of stainless steel
hot water storage tanks in their area. Suitable water preparation may be needed.
Design
– Dual shell fully plastic construction (corrosion-free).
– Space between internal and external tanks foam-filled with high heat insulation (low surface losses).
– Outer skin 3-4 mm thick (impact and shock proof).
Working method
The pressureless storage tank water is used as water storage tank medium. Useful heat is fed in and out by completely
submerged, spiral stainless steel corrugated tubes (1.4404).
The hot water zone in the storage tank works as a combination of heat storage and geyser (see Fig 2-2 and Fig 2-3). The cold
water flowing on removal of hot water is first fed down to the storage tank in the heat exchanger and provides maximym cooling
for the lower storage tank. The hot water zone is heated up, if necessary, with the gas condensing boiler. The flow through heat
exchanger for storage tank charging (SL-WT) is downwards from above. This raises the efficiency and the use of the solar unit.
The drinking water continually absorbs the heat from the storage tank water on its way up. The direction of throughflow by the
countercurrent principle and the spiral shape of the heat exchanger creates a distinct temperature layering in the storage tank.
As high temperatures can continue in the top area of the storage tank, it can achieve a high hot water output even on long draw-
off cycles.
– In the GSU 520S and GSU 530S models, the SL-WT ends about 40 cm above the tank floor. Only the hot water zone above
it is heated by the boiler. The tank volume below it is heated only if using solar energy.
– In the GSU320 and GSU 535 models, the SL-WT is taken to the tank floor. The entire storage volume is heated by the boiler
(greater hot water output readiness).
Water hygiene
The separation of pressureless storage tank water and hot water flowing through the corrugated tube heat exchangers ensures
optimum water hygiene in ROTEX GSU:
– Zones with low flow or no flow do not exist on the hot water side.
– Deposition of sediment, rust or other precipitants, which can occur in large volume tanks, is not possible.
– The water first stored is also removed first (First-in-first-out principle).
Storage tank water heating
The storage tank is first filled with pressureless storage tank water at the time of the initial start-up, and which is not exchanged
at a later date.
The storage tank water can be heated by different methods:
– by the integrated gas condensing boiler,
– by an additional solar system (ROTEX Solaris system) connected directly to the pressureless area,
– by an additional heat source connected directly to the pressureless area (e.g. hot water heat pump).
Maintenance
Calcium residues are dislodged as a result of thermal and pressure expansion and the high flow speeds in the heat exchangers
wash them away, scale deposits do not form. On the storage tank water side, the scale dissolved in the water can precipitate
only once. The smooth surface of the stainless steel corrugated tube heat exchanger does not allow any calcium encrustations
(no deterioration of the heat transfer performance during the operating period).
The filling level is only checked at the annual boiler inspection and water is topped up if necessary.
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