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DIY Indirect Heating Boiler - Connection Diagram To A Gas Boiler, Piping, Step-by-step Instructions With Drawings + Photos And Videos
DIY Indirect Heating Boiler - Connection Diagram To A Gas Boiler, Piping, Step-by-step Instructions With Drawings + Photos And Videos

Video: DIY Indirect Heating Boiler - Connection Diagram To A Gas Boiler, Piping, Step-by-step Instructions With Drawings + Photos And Videos

Video: How to Install a Combination Boiler/Water Heater | Ask This Old House 2022, December
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DIY indirect heating boiler - types, advantages, disadvantages and manufacturing technology

Floor standing indirect boiler with a capacity of 200 liters
Floor standing indirect boiler with a capacity of 200 liters

Private home owners have to use a variety of heating equipment, which requires significant maintenance costs and efficient operation. The indirect heating boiler is an excellent addition to the gas and electric heating system. The device reduces energy consumption for heating water and ensures its constant flow.

Content

  • 1 What is an indirect heating boiler

    • 1.1 Advantages and disadvantages of indirect heating equipment

      1.1.1 Video: experience of using an indirect type boiler

  • 2 Types of indirect heating boilers

    • 2.1 Types of heat exchanger
    • 2.2 Heat exchanger material
    • 2.3 Installation method
    • 2.4 Layout method
    • 2.5 Choosing a boiler for self-production
  • 3 Design features of the indirect boiler

    3.1 Boiler working principle

  • 4 Calculation of the main parameters of the boiler

    • 4.1 Volume and shape of the tank
    • 4.2 Power and length of the heat exchanger
    • 4.3 Table: length of copper heat exchanger for boilers with a capacity of 50-200 liters
  • 5 Required materials and tools
  • 6 Preparing the tank for assembling the water heater
  • 7 Manufacturing of an indirect heating boiler

    7.1 Video: indirect heating boiler from a gas cylinder

  • 8 Boiler piping for indirect heating

    • 8.1 Piping with three-way valve
    • 8.2 Piping with two circulation pumps
    • 8.3 Piping using a hydraulic arrow
    • 8.4 System with heating medium recirculation
  • 9 Features of the operation of an indirect boiler

    • 9.1 Cleaning and repairing the boiler
    • 9.2 Video: installation and piping of an indirect type boiler

What is an indirect heating boiler

An indirect heating boiler is a water heating tank that works in conjunction with central heating devices. Unlike traditional water heaters, an indirect type boiler does not require an electrical connection.

Indirect heating boiler
Indirect heating boiler

Indirect heating boilers can have different designs, but they all heat water using the energy of the boiler coolant

Water heating occurs due to heat exchange between hot water flowing through the heat exchanger and cold water, which is filled in the boiler tank. Externally, the boiler is a cylindrical container with a capacity of tens to several thousand liters.

Indirect water heaters are used both in private houses, the owners of which do not have the ability to connect to autonomous centralized heating, and in large industries where a large amount of hot water is required.

Advantages and disadvantages of indirect heating equipment

Among the advantages of an indirect type boiler are:

  • profitability (no electricity costs);
  • high performance of the equipment, limited only by the power of the heating boiler;
  • lack of direct contact between running water and coolant;
  • the ability to consume heat energy from several sources at once to increase the power and efficiency of the boiler.

The significant disadvantages of the equipment include:

  • high cost. An indirect heating boiler costs 1.5–2 times more than a direct type water heater;
  • insufficient power. To heat up a large amount of water (more than 100 l), it may take quite a long time - from 1 hour. In the assortment of some manufacturers there are boilers with a higher heating rate (30–35 min.), But their cost is unreasonably high;
  • large dimensions. The size of the equipment directly depends on the volume of the tank. Boilers with a capacity of more than 200 liters take up too much space, so they are installed in a separate utility room;
  • impossibility of year-round use. Effective work only during the heating season (autumn - winter). In summer, when the heating boiler is off, the water in the boiler is not heated.

    The efficiency of the indirect heating boiler
    The efficiency of the indirect heating boiler

    An indirect heating boiler prepares hot water longer, but it does not require an electrical connection

Video: experience of using an indirect type boiler

Types of indirect heating boilers

Modern indirect boilers have a variety of designs and shapes. In addition to the rounded thin-walled tank, there are boilers that have a more sophisticated design, allowing the equipment to be more economical and efficient. Equipment classification is performed according to several criteria.

Heat exchanger types

Indirect water heaters can have a heat exchanger of various designs:

  • single-circuit coil - a spiral-shaped thin-walled metal pipe located inside the storage tank. Due to the circulation of the heat carrier through the pipe, the coil heats up and transfers thermal energy to cold water, which is in the tank. This is the simplest and most affordable design on the market;

    Indirect heating boiler with one heat exchanger
    Indirect heating boiler with one heat exchanger

    An indirect heating boiler with a single-circuit coil is the simplest and most affordable option

  • double-circuit coil - a design similar to the option described above, with the only difference that the water heater provides the simultaneous supply of heated water and coolant for central heating. Such equipment is somewhat more expensive than a simpler analog, but much more efficient when it is necessary to heat a large amount of water;
  • tank-in-tank design - the equipment has a tank, consisting of larger and smaller containers. Inside the large tank there is water that needs to be heated, and inside the smaller one there is the coolant. Such boilers not only have a high rate of water heating up to 75–90 o C, but are also made in more overall buildings;

    Tank-in-tank boiler
    Tank-in-tank boiler

    Indirect boiler with tank-in-tank technology

  • combined boiler - the design of a water heater with two heat exchangers. The first is a conventional coil of aluminum or copper pipe. The second is made in the form of a tubular electric heater. Combined models have a rather high cost, but they also combine the functions of different devices.

Heat exchanger material

For the manufacture of a heat exchanger in the form of a coil and an internal tank, materials such as are used:

  • brass - low thermal conductivity, 100–110 W / (m ∙ ° C);
  • aluminum - average thermal conductivity, 200–240 W / (m ∙ ° C);
  • copper - high thermal conductivity, 360-390 W / (m ∙ ° C).

The higher the thermal conductivity of the heat exchanger material, the more expensive the boiler is.

Installation method

Depending on the installation method, the devices are divided into two types:

  1. Wall-mounted - the equipment is mounted on a hanging bracket fixed to the wall surface. The capacity of domestic wall-mounted boilers usually does not exceed 200 liters, but in the line of some manufacturers you can find designs with a capacity of up to 650 liters.
  2. Floor standing - the tank is installed on the floor surface in the immediate vicinity of the heating boiler. The average capacity of household floor-standing models ranges from 200 to 500 liters. Industrial versions have floor-standing installation only.

    Wall and floor boiler
    Wall and floor boiler

    Boilers are wall (left) and floor (right) versions

Layout method

According to the method of arrangement of structural elements, water heaters are divided into two types:

  1. Vertical is the most common layout method to save space in the room. Vertical devices have limited volume and dimensions, so this design is quite suitable for use in the private sector.
  2. Horizontal - has no clear restrictions on volume and dimensions. As a rule, due to their larger size, such devices have many additional functions. For example, a thicker insulation layer, recirculation and accumulation.

    Indirect type horizontal boiler
    Indirect type horizontal boiler

    Horizontal boilers can have a thicker layer of thermal insulation and a number of additional functions

Choosing a boiler for self-production

The general device of the indirect heating boiler is quite simple - with the ability to work with a power tool and welding, the water heater can be made independently.

For use in a private house where a family of three lives, a vertical boiler with a copper heat exchanger is sufficient. If the family is large, then it is better to choose a floor structure. This will make it possible to make the equipment of the required capacity, as well as to carry out proper thermal insulation of the tank.

It is not advisable to make your own boiler with a tank-in-tank heat exchanger. Firstly, you will need to find or make the tank itself, which will require a lot of effort and time. Secondly, in the manufacture of large-volume water heaters, the dimensions of the structure increase several times.

In addition, factory models manufactured using this technology have a special coating (enamel, ceramics, silver plating) on ​​the heat exchanger. It will not be possible to repeat the application of such a coating in a “garage environment”.

Design features of an indirect boiler

The indirect type boiler is a stainless steel tank. The inner walls of the tank are covered with a special material that not only protects the surface of the water heater from corrosion processes, but also reduces the concentration of harmful bacteria and microorganisms.

Indirect boiler design
Indirect boiler design

Diagram of an indirect type boiler device with a single-circuit coil

The rest of the boiler of the simplest design consists of the following components:

  • heat exchanger - a spiral tube or a smaller tank. Depending on the volume of the tank, it can be located in its upper and lower parts;
  • inlet nozzle - a fitting at the bottom of the device for supplying a pipe with cold running water;
  • outlet nozzle - a fitting for connecting a hot water outlet pipe;
  • magnesium anode - additional protection of the tank walls from corrosion processes;
  • internal thermometer - a device for measuring the temperature of water heating;
  • thermostat - a device that prevents equipment overheating;
  • control unit - rotary knob with divisions for setting the heating temperature;
  • thermal insulation - a layer of insulating material that helps maintain a given temperature of heated water;
  • outlet - valve for draining stagnant water;
  • revision - a large diameter hole designed for boiler maintenance, repair and modernization.

The design of new models of tanks may differ slightly and have a number of modifications from manufacturers, but in general, any indirect type boiler consists of the listed elements.

Boiler working principle

An indirect type boiler is part of the heating system and is connected directly to a gas, electric or solid fuel boiler, which heats the coolant using the energy released during fuel combustion.

The heat carrier circulates through the DHW system and passes through the heat exchanger located in the indirect heating boiler. Due to the release of thermal energy from the hot coolant, cold water is heated, with which the reservoir of the device is filled. From it, the heated water is transported through a pipe through the outlet to the bathroom, kitchen and other rooms with plumbing equipment.

Diagram of the indirect type boiler
Diagram of the indirect type boiler

The indirect type boiler can work with all types of heating boilers

When the heating boiler is turned off or when it goes into an economical mode of operation, the coolant cools down quickly. Due to the design, which provides for the insulation of the walls of the tank with urethane foam, the water in the tank cools very slowly. This allows you to use the entire volume of warm water for several more hours.

Calculation of the main parameters of the boiler

Before proceeding with the search for material and direct manufacturing, it will be necessary to calculate the minimum volume of the tank and the working length of the heat exchanger.

Tank volume and shape

The volume of the water tank directly depends on the number of residents permanently residing at the place of installation of the equipment. It is believed that a person consumes up to 80 liters of water per day. For the calculated value, it is recommended to take 45-50 liters per person. If the norm is exceeded, the water in the tank will stagnate, which will certainly affect its quality.

The shape of the tank is selected taking into account the pressure force in the water supply system. If the pressure is low, then it is allowed to use home-made boilers with a square tank. For high system pressures, only equipment with a round bottom and top can be used.

Square and rectangular boiler
Square and rectangular boiler

Square and rectangular storage tank boilers can only be used in water systems with low working pressure

The fact is that the increased pressure contributes to the emergence of bending forces on the walls of the tank, so a square or rectangular tank can be deformed. Tanks with a round bottom are more resistant to deformation due to better streamlining.

Heat exchanger power and length

In indirect vertical models, a copper coil is usually used as a heat exchanger between the inlet and outlet.

Copper coil
Copper coil

Copper pipe boiler coil

For self-production, it is best to use a copper pipe with a diameter of 10 mm. Such a product can be easily bent by hand without using any tools. When using the multilayer pipe be appreciated that heating the coolant temperature should not be over 90 for C, otherwise deformed tube, and the joints protekut - this will lead to a mixing of the water in the tank.

The length of the pipe required for the manufacture of the coil is calculated by the formula L = P / (3.14 ∙ d ∙ ∆Т), where:

  • L - pipe length (m);
  • d - pipe section (m);
  • ∆Т - temperature difference between heated and cold water (о C);
  • P is the power of the heat exchanger for every 10 liters of water (kW).

According to experts, for every 10 liters of water there should be at least 1.5 kW of thermal energy. With this in mind, you can calculate the length of the pipe for the manufacture of the coil.

For example, let's calculate the material for a coil that will be installed in a 200 liter boiler. The temperature of cold water supplied into the tank will be equal to 15 for C, and after heating is necessary to obtain water with a temperature of 80 of C: L = 1,5 ∙ 20 / (3,14 ∙ 0,01 ∙ 65) ≈ 15m.

Table: length of copper heat exchanger for boilers with a capacity of 50-200 liters

Storage tank volume, l Equipment power, kW Heat exchanger length, m Boiler tank diameter, m Loop diameter, m Number of turns
200 thirty 15 0.5 0,4 12
150 22.5 eleven 0.5 0,4 nine
one hundred 15 7.5 0,4 0.3 8
fifty 7.5 4 0,4 0.3 5

The number of turns of the coil depends on the bending method and the distance between the elements. Usually the coil is positioned so that the distance between the coils and the tank walls is at least 10–12 cm. The distance between the coils should not be less than 5 cm. The calculated values ​​for storage tanks of various volumes can be seen in the table above.

If an indirect type boiler must be equipped with a tubular electric heater, then the power is calculated based on the fact that a heating element with a capacity of at least 1.5 kW is needed to quickly heat 50 liters of water. In addition, any combination boiler must be equipped with a thermostat.

Required materials and tools

The storage tank of the device is made of heat-resistant plastic, stainless steel, aluminum or steel with a ceramic coating. As blanks for the tank, you can take plastic barrels for food products, aluminum tanks or an unnecessary gas cylinder.

For the manufacture of the heat exchanger, as indicated above, it is better to use a round or square copper tube. When assembling the heat exchanger of square tubes require bends under 90 on.

As a tool, you must prepare:

  • angle grinder;
  • electric drill with a core drill for metal;
  • argon arc welding apparatus;
  • set of wrenches;
  • disc for grinding and polishing metal;
  • sandpaper.

    Boiler assembly by welding
    Boiler assembly by welding

    To assemble a boiler, you will need to be able to work with a welding machine

Fittings, drain cock and other connecting elements are selected based on the dimensions of the pipe to be connected. Additionally purchased FUM-tape, safety valve, magnesium anode and nozzle for its installation.

Preparing the tank for assembling the water heater

For the manufacture of an indirect type boiler, you can use a new or old gas cylinder. This container is made of 3–4 mm thick stainless steel and is ideal for hot water applications.

Before assembling the heating structure, you will need to carefully prepare the cylinder. For this, the product is cut in half with a grinder. The inner surface of the container is cleaned using an angle grinder with a suitable attachment.

Preparing the gas cylinder
Preparing the gas cylinder

Before assembling the boiler, the cylinder must be opened and the inner surface must be cleaned

After that, the inside of the container is washed, dried and covered with nitro-primer paint. These works should be carried out without fail, otherwise, after the boiler is put into operation, the heated water will smell like gas.

When using a tank from other metal containers, the preparation is carried out in a similar way.

Production of an indirect heating boiler

The process of assembling a water heater may differ depending on the type of construction, but in most cases, equipment for gas and electric boilers is manufactured in the following sequence:

  1. In a previously prepared cylinder, two holes are drilled using an electric drill with a crown nozzle. One hole will be located at the bottom and used for supplying cold water, the other at the top for removing hot water.
  2. The resulting holes are cleaned, fittings and ball valves are mounted in them. Then another hole is drilled in the lower part, into which a tap is installed to drain the stagnant water.

    Installation of ball valves for water supply
    Installation of ball valves for water supply

    Holes are made in the lower and upper parts of the cylinder, into which taps are inserted to connect water supply pipes

  3. To make a coil, a copper pipe with a diameter of 10 mm is required. A spiral bend is best done with a pipe bender. If there is no such tool, then you can take any round workpiece - a large-diameter pipe, a log, a barrel, etc.

    Making a coil from a round copper pipe
    Making a coil from a round copper pipe

    Making a coil for a water heater from a round copper pipe with a diameter of 10 mm

  4. The coil is being manufactured according to the previous calculations. The ends of the heat exchanger are bent in one direction at a distance of 20–30 cm. To mount the coil, two holes are drilled in the bottom of the cylinder. Threaded unions are installed and welded into them.

    Elements for connecting the coil to the boiler
    Elements for connecting the coil to the boiler

    To connect the coil to the boiler, a threaded union is used

  5. Before installation, the coil is lowered into a bucket or large container of water and blown out. If the structure is sealed, then the coil is lowered into the cylinder, positioned relative to the inlet and outlet, and welded.
  6. If the balloon has been cut in the middle, then an anode is mounted in the upper part. To do this, a hole is drilled into which a threaded nozzle is screwed in, and a magnesium anode is already mounted in it. If the container is assembled from three separate parts - the bottom, the lid and the central part, then the anode can be installed at the last stage.
  7. Insulating material is mounted on the outside of the boiler. It is best to use sprayed polyurethane. Before application, all nozzles are protected with dense polyethylene and a cloth. If funds are limited, you can use conventional polyurethane foam, which after curing is wrapped in reflective insulation.

    Boiler thermal insulation
    Boiler thermal insulation

    For thermal insulation, the easiest way is to use mounting foam and foil insulation

  8. Attachments for suspension on brackets are welded to the back of the boiler. For floor-standing boilers, support legs from a steel angle or reinforcement are welded to the bottom of the equipment.

At the final stage, fittings and taps are screwed on and the top cover is mounted. If possible, the lid may not be welded, but clamping fasteners can be made of steel wire with a cross section of 3 mm.

In the manufacture of a boiler for joint use with solid fuel boilers, instead of a copper coil, a U-shaped steel pipe is used, which is mounted at the bottom of the device. From the side of the furnace or boiler, the pipe is connected to the outlet. The pipe is removed from the boiler and connected directly to the chimney.

Video: indirect heating boiler from a gas cylinder

Boiler piping for indirect heating

To connect an indirect type boiler, three working schemes are used:

  1. Piping with a three-way valve.
  2. Connection to two circulating sediments.
  3. Strapping with the use of a hydraulic arrow.

Piping with three-way valve

A piping scheme using a three-way valve is used most often, especially when a large amount of hot water is consumed. For this, two heating circuits are installed in the system. The first is the main circuit used for space heating. The second one is designed to heat water in the boiler.

Boiler piping diagram with a three-way valve
Boiler piping diagram with a three-way valve

The piping scheme for an indirect heating boiler with a three-way valve is used most often

For uniform distribution and regulation of the volume of the heating medium entering the boiler, a three-way valve is used, which is connected to a thermostat.

The principle of operation of the system is quite simple: if the temperature in the storage tank drops below the set value, then the valve redirects part of the coolant to heat the water in the boiler. After heating the water, the coolant returns back to the heating circuit.

Piping with two circulation pumps

An indirect water heater is installed in a system with two circuits: boiler and heating. A recirculation pump is used to regulate each individual circuit. In this case, the pump on the boiler circuit is mounted in front of the pump of the heating equipment.

Boiler piping diagram with two circulation pumps
Boiler piping diagram with two circulation pumps

In a piping scheme with circulation pumps, the supply of coolant to the boiler is automatically regulated

Both pumps are connected to the boiler thermostat. When the water in the boiler cools down, the thermostat turns on the corresponding pump, which redirects part of the flow from the heating and vice versa.

Harnessing using a hydraulic arrow

Piping using a hydraulic separator is used in central heating systems consisting of two or more circuits. If, in a system without a hydraulic switch, the redistribution of flows in the circuits necessarily affects the operation of any equipment, then when it is installed, a smooth redistribution of cold and hot flows occurs.

Boiler piping diagram with a hydraulic arrow
Boiler piping diagram with a hydraulic arrow

The boiler piping scheme with the installation of a hydraulic separator ensures the smoothest distribution of cold and hot water flows

For example, a hydraulic separator is necessarily installed in private houses, where, in addition to an indirect heating boiler, a floor heating system is connected to central heating. The scheme of this strapping is rather complicated in execution, especially with a large number of equipment. Therefore, it is better to entrust the installation work to specialists.

Heating medium recirculation system

This piping scheme is used when it is necessary to minimize the rate of water heating in the boiler, since with frequent downtime, the water in the tank cools down quickly, and it takes from 30 to 60 minutes to reheat it.

To do this, a "return" to the water heater is installed in the pipeline from the boiler to the water tap. A circulation pump connected to a thermostat is also installed in this area.

When water stagnates and cools in the pipeline, the thermostat turns on the pump, which redirects the cooled water back to heating. When the water supply is resumed, the user does not have to wait for it to heat up, since it will already be warm.

Features of the operation of an indirect boiler

For proper functioning, the boiler must be installed on a flat, solid surface. When installing the wall-mounted boiler, appropriate fasteners are used that are designed for the weight of the device filled with water.

A tank with a capacity of up to 100 liters is attached to a dowel-nails 100 mm long, and for equipment with a capacity of 150-200 liters, you need to use fasteners up to 150 mm long. It is advisable to hang the boiler on concrete or brick walls.

On the line supplying cold water, a check valve must be installed in front of the boiler, which will prevent hot water from entering the cold circuit.

Connecting an indirect heating boiler to a recirculation system
Connecting an indirect heating boiler to a recirculation system

The indirect heating boiler is connected to the system through a check valve

The main problem in the operation of boiler indirect type - is the formation of scale within the storage tank and the heat exchanger when heating of water over 80 of S. It is therefore advisable to reduce the temperature to 40-50 comfortable with moderate hot water flow (dishwashing) of C. This will significantly prolong service life of the equipment.

Boiler cleaning and repair

If the boiler is used frequently, the tank should be cleaned once a year. To do this, a concentrated solution of citric or acetic acid is pumped into the tank and heated to a temperature of 80–90 o C. After 20–30 minutes, the liquid is drained. If the heating system uses a coolant in the form of ordinary water, then for preventive purposes, the heat exchanger is cleaned in a similar way.

If a leak appears at the joints of the pipes, it is necessary to disassemble the problem area and re-install it using a larger amount of sealant. Instead of plumbing flax, you should use more modern materials, for example, FUM tape or plumbing thread.

Video: installation and piping of an indirect type boiler

An indirect water heater is an equipment that must be installed in every private and country house where gas or electric heating is used. This will reduce the cost of hot water supply by 15–20%, which will become a very tangible savings in the face of constantly growing tariffs.

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