Indirect Water Heater

Key points in selecting Indirect Water Heater (coil or double shell) :

Coil and double-shell Indirect Water Heater is some of the most important water heating equipment in buildings. Coil, double-shell, expansion, and cold water storage tanks are usually produced using galvanized steel plates or steel plates.

The thickness of the steel plate used in manufacturing coil, double-shell, fuel storage, etc. tanks must be calculated according to international standards for pressure vessels.

Another important factor for the thickness of steel plates used in the coil or double-shell hot Indirect Water Heaters is their operating temperature (temperature of the fluid inside) and corrosivity of water.

According to engineering standards, the temperature of warm tap water is usually between 50-60 and, therefore, the temperature of the warm tap water stored in a coil or double-shell tank must not fall below 50 degrees; otherwise, a bacteria with green color known as legionella, whose growth temperature is 25-50  will proliferate in the tank and cause extra costs of periodic washing of the tank for removing the bacteria.

In coil and double-shell hot Indirect Water Heaters, the welded seams must be covered with epoxy paint (thickness of 140 micrometers) or cold zinc painting (even when using galvanized plates).

Approximate capacities for coil or double-shell hot Indirect Water Heaters :

To estimate the hot water capacity required by a building (coil or double-shell) considering the unit count, building use, demand factor, simultaneous consumption, and consumption rates, each residential unit requires 100-200 liters of capacity in the coil or double-shell hot Indirect Water Heaters.

Hot galvanized double-shell tanks :

• Double-shell tanks are installed in a boiler room to provide the warm water required in a building. The hot water produced by the boiler flows between the two layers and heats the cold tap water entering the main tank;
• In double-shell tanks, the higher pressure in the inner part due to the urban water supply means its galvanized plate must be thicker than the outer shell which is only in contact with the hot boiler water.
• The plate thickness in double-shell tanks is represented with two numbers, for example, a 3-5 double-shell tank means the inner and outer shells are 5 and 3 millimeters thick.
• Double-shell tanks are produced in different capacities from 300 to 1500 liters and in both horizontal and vertical models.
• Double-shell tanks can heat a large amount of water in a short time, even without using the hot water circulator pump of the boiler and by using the gravitational flow of the circulating water. This is an advantage for apartments, pools, and all places requiring hot tap water.
• A problem with double-shell tanks is that they are difficult or impossible to repair in case of small punctures or leaking spots.

Benefits of coil tanks :

• Coil tanks are produced in vertical and horizontal models. They are used in the central heating systems to produce hot tap water from the cold supply water.
• Their heating mechanism uses the thermal energy of the hot water or steam produced by the central boiler in the coils implemented in the tank to transfer the heat to the input cold water (same as a heat exchanger) in order to provide hot tap water.
• If the lowest part of a horizontal coil hot Indirect Water Heater is higher than the collector of the boiler, it is possible to provide hot tap water without using a hot water circulator pump.
• The body of coil tanks is usually made of hot galvanized plates, but if using non-galvanized plates, the inner surface is coated using epoxy paints to prevent oxidization.
• The capacity, thickness, and type of plates and lenses, dimensions (for installing in the boiler room), and coil type and its thermal exchange surface must be determined by technicians.
• A general rule for calculating the heat exchange surface of a coil in coil tank is that the total heat required by the tank (based on the tank capacity and temperature difference of the input cold water and output hot water) is divided by the coefficient of thermal conductivity (where U is the coefficient of the coil material) multiplied by the logarithmic temperature difference of the input and output water.
• Compared to double-shell tanks, coil tanks have the advantage of easy repairs in case of leakage due to having a single shell, faster heating, and higher efficiency due to the use of coils (or heat exchangers) inside the tank.
• Similar to other Indirect Water Heaters, coil Indirect Water Heater are produced in horizontal and vertical models according to the calculations and order of an expert to be installed in the boiler room of hotels, hospitals, residential complexes, offices, factories, pools, and other places with the proper guarantee.
  
  

Technical considerations for installing Indirect Water Heaters :

A.For all hot Indirect Water Heaters such as the coil or double-shell tanks, we must implement safety valves for pressure and temperature.
B.The water overflow tube must be extended from the expansion tank on the rooftop to the boiler room.
C.If the inner shell of a double-shell tank or the hot water coil of a coil tank is punctured, the water in the supply system gradually leaks into the heating system and water will start overflowing from the expansion tank on the rooftop.
D.All diesel fuel Indirect Water Heater must have a vent tube.

Schematics of pipework in a vertical hot water coil tank :

Indirect Water Heater are made of different materials such as polyethylene, stainless steel, galvanized plates, and fiberglass to meet different applications. When selecting a storage tank, we need to consider the type of stored fluid, operating temperature and pressure, application, etc. to prevent a number of issues.
Here we explain the Indirect Water Heaters used in buildings considering their materials, pros and cons, applications, and usages.
Overall, Indirect Water Heaters are used to store different liquids such as drinking water, hot water, chemicals (acidic or alkaline), fuels (oil, diesel, etc.), various fluids and granules for long periods of time.

Polyethylene storage tanks :

1. Polyethylene materials are made of high-quality thermoplastics. They are completely harmless to humans, and the tanks produced using them can store edible products. The tanks are highly resistant to physical and chemical damage.
2. Polyethylene tanks are produced in horizontal and vertical models and various sizes and even come in different shapes to fit in different spaces.
3. Polyethylene tanks are made in colorless, single-layer, dual-layer, triple-layer, quad-layer, foam cover, anti-bacterial, and more types to fit different conditions.
4. Polyethylene storage tanks offer many benefits including good price, hygiene, resistance to climatic conditions, lightness, leak resistance, extensible capacity via connecting multiple tanks, and easy installation and maintenance.
5. Polyethylene storage tanks are the best solution to storage of water without changing its taste or aroma.
6. Polyethylene tanks are suited for storing most chemicals;
7. Kept at 20 ^oC, polyethylene tanks last up to 50 years.
8. Polyethylene tanks can withstand long heat and cold at -50 to 45 ^oC. In mountainous areas, their double-shell structure and the insulation capability of polyethylene give them better performance compared to other types.
9. Some polyethylene tanks are lightweight and prevent heat loss from the walls due to employing a foam layer, which helps maintaining temperature of the liquid inside.
10. Considering their price and weight, polyethylene tanks are better than stainless steel and fiberglass tanks.
11. Transparent tanks make it possible to observe the liquid inside.
12. Polyethylene tanks can be moved frequently to be used in different places.
13. The sunscreen layer in polyethylene tanks prevents the growth of algae.
14. Polyethylene tanks are highly anti-corrosive and can best preserve corrosive agents such as acids and active chemicals.
15. Polyethylene is chemically inactive and does not react to other agents.
16. Therefore, this material is suitable for preserving substances such as water that require hygiene, no change in aroma or taste, and other properties in long term.
    
    

When using polyethylene tanks for storing drinking water, do the following to prevent algae growth :

• Colorless, single-layer tanks are suited for storing water indoors;
• Double-layer tanks are suited for storing water outdoors in temperate regions;
• Triple- and quad-layer foam-cover tanks are suited for storing water outdoors in hot and cold climates.

Keep the following in mind when using polyethylene tanks for storing fluids :

• Do not store liquids hotter than 60 ^oC in the tanks;
• The input and output fittings of the tanks must be installed by sales representatives or under their supervision.
• Prevent the impact of sharp objects or placing concentrated loads on tanks shells;
• Place the tanks where they can be properly accessed, inspected, controlled, and maintained.
• Note: do not overly tighten the fittings, as it may damage the tank. The tightness just needs to sufficiently seal the joints.

Placing an Order and Warranties Indirect Water Heater :

• Offering best price guarantee for all products, the prices for Indirect Water Heater presented by DamaTajhiz are up-to-date and discount-included (see Best Price Guarantee at DamaTajhiz.com).
• Find the technical information you need for comparison and purchase for several models of Indirect Water Heaters from reliable manufacturers at DamaTajhiz.com, under Indirect Water Heater category.

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Ft² 0.0982 = inch 8/3 per foot of pipe length
1 Gal. (am.) = 3.785 Lit
Ft² 0.1309 = 2/1 inch per foot of pipe length
1M3 =35.315 Ft3
Atm=10.331 meter the height of the water tower
1Atm = 14.7 PSI