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Vitowell comfort Classic (Slim)

Storage Water Heater

Vitowell comfort Classic (Slim) is a robust, reliable and secure electric storage water heater for capacities between 15 and 30 litres. A water-resistant casing material assure maximum safety.

Stepless temperature adjustment
Ceratech Technology tank coating
Slim and cube design

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Stepless temperature adjustment

For high comfort

Ceratech Technology tank coating

For efficient heating

Splash-waterproof IP X4 casing

For maximum safety

Double-safety thermostats

For protection against overheating

Durable structure

Made of high-quality ABS material

Fast heating time

And high-density PU Insulation for energy efficiency

Large magnesium anode

For protection against water tank corrosion

Available in two design options

Slim or cube design

Features of the Vitowell comfort storage water heaters

Vitowell  comfort Classic: robust and safe

The  Vitowell comfort Classic line equips you with a reliable and secure water heater. Viessmann adopts the exclusive Ceratech Technology enamel coating formula to extend the durability of water tanks. Acid corrosion and alkaline resistance, temperature and pressure resistance meet the latest German quality standards to assure long-lasting durability of the heater at its core. A high-quality, water-resistant casing material provide maximum safety.

Ceratech Technology®

Viessmann adopts the exclusive Ceratech Technology® enamel coating formula to extend the durability of its water tanks. The anti-corrosion function performed by the internal water tank ceramic layer has been developed with decades of expertise and continuous improvement of materials and applied technology. The ceramic layer has a particularly high density and a perfectly smooth surface, undergoing a 100% quality check off the production line. Acid corrosion resistance, alkaline resistance, temperature and pressure resistance - all these technical characteristics are in line with the latest German quality standards to guarantee a long-lasting durability of the heater at its core.  

Safety and energy efficiency

The Vitowell comfort Classic heater has a dual-safety thermostats for protection against overheating. Its high-density PU Insulation also allows for energy efficiency.

Two design options

Vitowell  comfort Classic heaters are available in two designs: cube and slim. The slim heater sticks out by its simplistic, modern design. Thanks to its shape, it can also be concealed in a false ceiling. The traditional, compact design makes the cube heater particularly suitable for small bathrooms.


Check the dimensions of  Vitowell comfort Classic water heaters in the following overview to assure that the device fits well into your home.

Vitowell comfort Classic Slim
Dimensions / Capacity  20 l  
A (mm)  630  
B (mm)  279  
C (mm)  279  
D (mm)  100  
E (mm)  140  
F (mm)  116  

Product details


20 l: 2500W/230V


20 l: 9 kg

FAQ on storage water heaters

A power trip at home  caused by the turning on of the electric water heater is usually related to electrical wiring/ electrical supply problems that fall under these common causes:

  • Wrong wiring connection, or worn/damaged cables that has fused or come into contact with each other, leading to a short circuit
  • Failure to wire to a dedicated water heater power point/ front flex outlet. A 3-pin socket outlet should not be used because its power rating is insufficient to support water heater.
  • Sharing of the power point/socket with other electrical appliance(s) resulting in electrical overload. The power point for water heater should never be shared.
  • Faulty heater switch / power point.

Please consult a Licensed Electrician to check and rectify any electrical problem. If the power trip persists even after an electrical inspection, kindly contact Viessmann Service Support to check and service your water heater unit.

Before turning on the electrical supply, turn on the water supply to ensure that your storage water heater is completely filled up with water. This is an important step to avoid dryburn and damage to the thermal components such as thermostat and heating element.

Make sure that the water inlet and outlet have been connected correctly, otherwise colder water in the storage tank will be dispensed first. The red and blue rings on the underside of the Viessmann storage water heater indicate the hot water outlet and cold water inlet respectively.

If the above conditions have been fulfilled and your water heater is still not working, please contact Viessmann Service Support to check and service on the water heater unit.

There are 2 common reasons why the water from your storage heater is not hot enough:

  • Water not fully heated up yet: give some time for the water to be heated up before use.
  • Water flow rate at water fixture is too high:  hot water stored at the heater is being consumed faster than the rate at which the cold water refilled into the tank can be fully heated up. In such a situation, turn on the water fixture tap partially instead, or install a flow restrictor to reduce the water flow.

Use the light indicators on Viessmann storage water heaters to easily recognise whether the heating process is completed.

  Heating in progressKeep Warm mode    
Vitowell comfort ClassicOrange indicator lightLight off when heating is completed    
Vitowell comfort Premium/DeluxeOrange light on LED ringBlue light on LED ring    

Under Singapore regulation SS636:2018, pressure relief valve is necessary to be installed at the cold water inlet of the storage water heater to prevent tank overpressure, leakage, or explosion in worst case. You can find a pressure relief valve included in the accessory pack of every Viessmann storage water heater unit supplied.

Whenever the water pressure at the water heater is too high, the pressure relief valve will release excess pressure through releasing/dripping of water. This releasing/dripping of water will stop when the water pressure is reduced and stabilized.

To check if releasing/dripping of water arise from the normal operation of the pressure relief valve, you can simply turn on water at the shower for 20-30 sec, and observe if the drip at the pressure relief valve stops.

If water dripping occurs permanently, kindly contact Viessmann Service Support to check and rectify on the possible faulty pressure relief valve.

To ensure the best performance from this appliance, it is recommended to replace the magnesium anode, flush out any deposit of salts in the heater tank and descale the heating element once every two years. The maintenance cycle may vary depending on the water quality. It is best to engage a Licensed Plumber or service technician to perform the maintenance operation.

How can we help?

Tap on the button below to WhatsApp us at +65 8028 0468 during office hours (Mondays – Fridays, 9am – 6pm), or select Contact Form below to provide us with details of your enquiry. We will get back to you as soon as possible.

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