Technical manual for installation and use of Inox Boiler Termocasa

1. Overview

1.1 Pressurized water tank (tank equipped with heat exchangers / coils)

When installing a central heating system or solar panels for domestic hot water heating, the selection of the boiler and its characteristics is very important because its function is to take the heat from the central heating system or solar panels and transform it into domestic hot water in a pressurized system.

1.2 Models of stainless steel pressure water tanks (boilers) Termocasa.

– TMC 150 DUAL
– TMC 200 DUAL
– TMC 300 DUAL
– TMC 300 DUAL EXTENDED
– TMC 500 Dual

1.3 Pressure water tank protection
The inner lining of the pressurized water tank is made of food-grade SUS304 stainless steel, which is welded by a fully automatic argon arc welding machine/robot. It is corrosion-resistant and non-deformable, ensuring a long product life together with the magnesium anode.
To provide complete protection to the water tank, it is recommended to inspect and replace the magnesium anode as often as necessary, and replace it at least once a year, depending on its consumption due to non-compliant water (with limescale, etc.).

1.4 Efficiency
The unique heat exchanger configuration ensures complete heating of the water in the pressure tank, along with the appropriate dimensions of the heat exchanger/coil surface.

1.5 Insulation
Injection molded polyurethane foam for effective thermal insulation. The insulation does not contain CFC or HCFC

1.6 Surface treatment
The material of the pressure water heater casing is galvanized sheet metal.

1.7 Features
– Large battery, high heating capacity.
– Maximum working pressure of the coil up to 12 Bar.
– It is equipped with a connection for domestic hot water recirculation.
– Magnesium anode protects the system against corrosion.

1.8 Tips

1. This manual is part of the hot water tank accessories and must be kept and handed over to the buyer in electronic or paper format.
2. Please read the instructions and tips below carefully as they will help you install, use and maintain your hot water tank without any problems.
3. The installation fee will be paid by the buyer and must be installed by a licensed installer according to the instructions in this manual.
4. It is forbidden to use the hot water tank for any purpose other than heating domestic hot water, the manufacturer is not responsible for damage caused by improper or incorrect use.
5. Installation, maintenance and any other adjustments must be carried out by professionals in accordance with the operating procedures and instructions in this manual.
6. The seller will not be liable for any injuries to persons or animals or other material damage caused by improper installation of the equipment.
7. Do not leave packaging materials (staples, plastic ties, foam, etc.) within the reach of children to avoid dangers.
8. Do not allow children or inexperienced personnel to use the water tank.
9. We recommend that you protect the body and external components of the boiler from moisture.
10. Maintenance of the hot water tank will be carried out by an installer authorized by the seller, and during maintenance visits it is mandatory to present the original warranty certificate and the purchase invoice.

2. Technical specifications

(The following data is for informational purposes only)

	TMC 150 DUAL	TMC 200 DUAL	TMC 300 DUAL	TMC 300 DUAL EXTENDED	TMC 500 DUAL
Nominal water tank capacity (L)	150	200	300	300	500
Maximum water tank pressure (BAR)	7	7	7	7	7
Maximum working temperature (℃)	80	80	80	80	80
Water tank material	SUS304-2B	SUS304-2B	SUS304-2B	SUS304-2B	SUS304-2B
Serpentine surface up/down (sqm)	0,4 / 0,8	0,6 / 0,9	1 / 1,4	1,6 / 1,6	1,4 / 1,8
Maximum coil pressure (BAR)	12	12	12	12	12
Serpentine material	SUS304-2B	SUS304-2B	SUS304-2B	SUS304-2B	SUS304-2B
Insulation thickness (mm)	50	50	50	50	60
Gross weight (kg)	46	55	80	83	125
Dimensions (mm) (height X diameter)	X 1500 470	X 1470 550	X 1800 580	X 1800 580	X 1920 580

3. Installation and operation

If the voltage at the equipment's power outlet is not stable, it is recommended to check and fix the problem or use a voltage stabilizer that must be 4× the equipment's power, and capable of supporting the current and voltage at startup and during equipment operation.

The pressurized water tank with heat exchanger (serpentine) can conveniently provide hot water for domestic and industrial use. The pressurized water tank is connected to the water supply network through the cold water connection, and hot water is supplied to each point of use through the hot water connections. When the hot water is released, the cold water enters the pressurized water tank and is heated to the set temperature in the pressurized water tank.

It is recommended to set the domestic hot water temperature between 40℃ and 65℃ to ensure the best performance and to sanitize the pressurized water tanks, to keep heat loss to a minimum and to inhibit the formation of deposits. Non-professionals should not perform the following operations, otherwise the warranty will be void:

3.1 Location of the pressurized water tank
Please install the pressurized water tank as close as possible to the heating source (such as heat pump, solar collector, gas boiler, etc.), and the floor must be able to support the total weight of the pressurized tank filled with water.

3.2 Piping connection and preliminary operation

3.2.1 Refer to the structure diagram of the pressurized water tank in the instruction manual to connect all the pipes. After the connection is completed, it should be tested to ensure that there is no leakage at the pipe joints. The hot water pipes should be insulated.
3.2.2 Make sure that the useful thermal power of the pressurized water tank exceeds the power that can be released by boilers and other heat sources by more than 15%.
3.2.3 If the quality of the water in the circuit is too hard, it is recommended to install a suitable softener on the water pipe of the pressurized water tank, if there are impurities in the water in the circuit, it is recommended to install a suitable filter.
3.2.4 Make sure that the circulation pumps have sufficient flow and safety protection and are functioning properly.

Major safety reminder: The pressure water tank must be installed with a pressure relief valve suitable for the maximum working pressure of this product ≤7Bar in accordance with national standards. The pressure relief valve must be directly connected to the pressure water tank. The discharge pipe shall be connected to the pressure valve and discharged into a safe, frost-free drainage environment.
IT IS MANDATORY to install an expansion vessel on the domestic hot water outlet circuit, a vessel whose role is to ensure the correct functioning of the domestic hot water production installation and the water supply system. It allows the water to expand and contract. It also prevents damage that may occur as a result of pressure variations. Among the benefits brought by the expansion vessel are:

• prevents serious accidents from occurring;
• it is important in solar installations;
• prevents the boiler safety valve from opening;
• protects pipes, not just the heating system;
• If there is no expansion vessel, then the safety valve will open, which will lead to water loss, reduced life span or damage to the equipment, and various dangers.

The recommended water pressure is 2-3 bar, and to obtain it, it is recommended to use a correctly sized pressure regulator and expansion vessel.

The pressure relief valve must be manually drained (at most every 90 days) regularly to prevent blockage. At the same time, when the coil heat exchanger is connected to other energy sources, a safety valve with a maximum working pressure of <7Bar must be installed.

In theory, stainless steel is resistant to corrosion, but in practice there are several situations in which even a stainless steel water heater can corrode or puncture over time.

Here are the main real and technically explained cases where this happens:

1. Pitting corrosion – due to chlorides in water

Cause: high concentration of chlorine ions (Cl⁻) in water (e.g. from salt, hypochlorite, detergents, pool water, or even hard chlorinated drinking water).

Mechanism: Chlorine ions destroy the passive chromium oxide film that protects stainless steel.

Once the film is locally damaged, pitting occurs.

Affected areas: the inside of the tank, joints, welds, areas with limescale deposits.

2. Galvanic (electrochemical) corrosion

Cause: direct contact between stainless steel and a less noble metal (copper, steel, aluminum, zinc) + the presence of conductive water.

Mechanism: the stainless steel becomes the cathode, and the other metal the anode, which dissolves – but sometimes the local effect reverses at the micro-scale and micro-perforations appear in the stainless steel.

Example: Copper pipes connected directly to stainless steel fittings without dielectric inserts → in 2–3 years traces of oxide or even holes appear.

3. Water with acidic pH or very high conductivity

Cause: well or borehole water with pH < 6, or high content of nitrates, sulfates, iron, manganese.

Mechanism: the passive chromium oxide film dissolves → generalized corrosion.

Symptoms: dull areas, rusty portions, metal smell, colored water.

4. Limescale deposits + stagnation + dissolved oxygen

Cause: hard water + high temperatures (60–80°C) → limescale deposits that insulate stainless steel portions.

Under the layer of limestone, sub-deposition corrosion occurs.

Mechanism: dissolved oxygen reacts locally → pitting under the crust.

It accelerates if the boiler is unused for a long time (stagnant water).

5. Absence or depletion of the magnesium anode

Even though it's stainless steel, the boilers have a protective anode that takes over the electrochemical charge.

If the anode is not checked periodically, at least annually, the stainless steel can become anodic and perforated.

Especially in waters with high conductivity.

6. External agents – detergents, chlorine, steam, sea air

If the boiler is installed in bathrooms, technical rooms or damp basements where there are chlorine vapors or detergents, external corrosion may occur on the casing or even on the welds.

7. Electrical surges or faulty grounding

Cause: the boiler is powered from a network without proper grounding → a weak current appears through the water or through the boiler body.

Effect: Electrolytes in water accelerate corrosion.

Sometimes it leads to perforation within 1–2 years in the connection area.

How to prevent:

• Assembly with dielectric connections between dissimilar metals.
• Check and replace the magnesium anode whenever it is consumed.
• TAC (Template Assisted Water Softening) filter
• Crystallization), or magnetic anti-limescale filter at the inlet.
• Avoid strong chlorination of water.
• Check the grounding of the electrical installation.
• Clean the boiler periodically (every 1–2 years) for deposits.

Water quality and recommended softening

To protect the stainless steel boiler, the water used must comply with: hardness max. 10°dH, chlorides max. 250 mg/L, pH 6,5–8,5. Classic salt softeners (NaCl/KCl) are not recommended, as chloride ions can cause corrosion and perforations, not covered by warranty. It is recommended to use TAC (Template Assisted Crystallization) systems, which prevent limescale deposits without adding chlorides and protect stainless steel in the long term. It is recommended that the TDS value does not exceed 500 ppm. High TDS values, especially in the presence of chlorides, accelerate corrosion processes and lead to equipment damage, situations that are not covered by the warranty.

System diagram with central heating system for domestic hot water heating
(water tank with a coil)

System diagram with heat pump with puffer, boiler and solar panel
(with intermediate exchanger)

1) water well or brine circuit, 2) water filter, 3) non-return valves (2 pcs. for water-water installation), 4) water well pump or brine circuit, 5) heat pump, 6) recirculation pump, 7) 3-way solenoid valve Termocasa (2 pcs.), 8) hot water boiler outlet, 9) domestic hot water boiler, 10) cold water boiler inlet, 11) storage tank (buffer), 12) building heating circuits, 13) sense flap, 14) recirculation pump, 15) direct absorption solar panel, 16) intermediate heat exchanger, 17) recirculation pump, 18) recirculation pump.

(ATTENTION!!! The surface area of ​​the coil in the boiler must be correctly sized depending on the power of the heating system/heat pump – see the RECOMMENDATIONS chapter)

The 3-way valve (7) from the green circuit and the recirculation pump (18) will be powered by the solar panel automation.

4. Commissioning

4.1 Fill the pressurized water tank with water at the cold water inlet and open the tap on the pipe connected to the hot water outlet to release the air in the circuit.

4.2 Fill the primary circuit and bleed the air from the circuit. Follow this procedure to fill the secondary circuit if necessary.

5. Maintenance

5.1 Before performing any maintenance on the pressurized water tank, the water tank must be emptied and the water supply must be cut off.

5.2 When cleaning the external parts of the pressurized water tank, please use a damp cloth and a suitable commercially available cleaning agent, do not use corrosive products such as solvents, alcohol, etc.

5.3 It is recommended to descale the pressurized water tank once a year and check and replace the magnesium rod. Draining and descaling steps: close the water inlet valve of the water tank, open the water end valve, and then open the waste water outlet valve to release the water and water in the pressurized water tank.

6. Warranty terms

6.1.1 This warranty is only valid when the equipment is installed by qualified personnel. The warranty is void in the following cases:

• Unusual environmental conditions:
• Installed outdoors in places subject to frost or weather;
• If you use rainwater or well water or corrosive water that does not meet national standards;
• All types of damage caused by vibration or dropping during the handling process after delivery from the factory;
• If the magnesium anode is not replaced as often as it is consumed, and if it is not consumed, it will be replaced every 12 consecutive months.

6.1.2 The warranty applies only to the pressurized water tank and its components, with the total exception of electrical or hydraulic installations, losses that could be avoided by immediate repair of the pressurized water tank are not covered by the warranty.

6.2 The installation does not comply with regulations, national standards and industry rules, in particular:

6.2.1 Missing or incorrectly installed security components

6.2.2 The installation of safety components does not comply with national standards, and old safety components are used on newly installed pressure water tanks.

6.2.3 Changing the safety component setting after seal damage.

6.2.4 Abnormal corrosion caused by improper water connection (direct contact between iron and copper)

6.3 Insufficient maintenance, improper use of the water softener connected to the water tank

6.3.1 Incorrect installation of safety components

6.3.2 Overpressure due to lack of maintenance of safety components (see instructions).

6.3.3 Traces of external corrosion.

6.3.4 Failure to maintain equipment (replacement of magnesium anode).

7.Troubleshooting

symptoms	Case analysis	Solution
Lack of water	Water cut off or water inlet and outlet valves in the water tank are closed _____ Frozen cold water pipes in winter	Open the cold and hot water taps of the water tank _____ Wait for natural defrosting
The water is not hot.	Bad weather (solar panels) or central heating not working _____ There is air in the coil and the circulation pump is not working properly. _____ System control or pipe connection, incorrect settings _____ Limescale deposits on coils after long-term use at high temperatures	Use auxiliary heating, electric resistance _____ Circulation pump check and coil venting _____ Consult the manual or contact the manufacturer. _____ Add special water tank descaling agent to clean the water tank
Leaks in the water tank	Aging of the electrical resistance, the sealing gasket or the magnesium rod _____ The water tank overpressure works for a long time _____ The water tank uses domestic drinking water that does not meet national standards	Replace the electric resistance, magnesium rod or sealing gasket _____ Replace the pressure valve _____ Install appropriate filters

Warranty card
Product model:
Date of purchase:

From the date of purchase of this product, the main body of the water tank is guaranteed for three years, and the auxiliary parts are guaranteed for one year.

In one of the following situations, it is not part of the warranty scope and maintenance materials will be charged:

1. Products beyond the warranty period;
2. Products that are artificially damaged due to improper use, maintenance and storage by consumers;
3. Products that have been installed, dismantled or repaired by personnel not authorized by the company Termocasa;
4. Products without a warranty certificate and invoice or an amended warranty certificate;
5. The product barcode on the warranty card does not match the barcode on the product;
6. Products damaged by external factors.

Note: This warranty card, product barcode and valid purchase invoice are warranty certificates, please keep them. înappropriately.

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