How to make an indirect heating boiler with your own hands?


Indirect heating boiler

Even res­i­dents of apart­ment build­ings equipped with a cen­tral­ized hot water sup­ply sys­tem face the prob­lem of lack of hot water.

If the own­ers of pri­vate hous­es did not take care of installing a dou­ble-cir­cuit boil­er that pro­vides the cot­tage with both heat and hot water, then they also begin to look for a way to get enough heat­ed water for house­hold needs.

Advantages and disadvantages

Even in the ide­al case, when the house is gasi­fied, installing a geyser does not always com­plete­ly solve the prob­lem of obtain­ing hot water in suf­fi­cient quan­ti­ties.

It takes some time for hot water to appear in the tap, and when using the show­er, the water tem­per­a­ture can drop sharply if you start using the water tap in the kitchen. These short­com­ings are always inher­ent in instan­ta­neous water heaters, where water is heat­ed using gas or elec­tric­i­ty.

Hajdu PT1000When using an indi­rect heat­ing boil­er, such prob­lems do not appear, since they the device allows you to keep the tem­per­a­ture of the water con­stant.

If we cal­cu­late the cost of obtain­ing hot water when using instan­ta­neous water heaters and com­pare it with the cost of heat­ing water with indi­rect heat­ing boil­ers, it is obvi­ous that the work of the lat­ter is much cheap­er for con­sumers.

How­ev­er the pur­chase of such an indus­tri­al water heater will cost a con­sid­er­able amount. Usu­al­ly the required vol­ume of con­struc­tion is cal­cu­lat­ed based on the num­ber of peo­ple liv­ing in the house. At least 50 liters of hot water are required per day for one per­son.

For a fam­i­ly of four, it is nec­es­sary to pur­chase an indi­rect heat­ing boil­er with a min­i­mum vol­ume of 200 liters. Depend­ing on the man­u­fac­tur­er, the pur­chase of such a mod­el will cost the own­ers of the house 35–450 $.
Since its design is not too com­pli­cat­ed, many home­own­ers make the device them­selves.

The principle of operation of an indirect heating boiler

Before under­tak­ing the man­u­fac­ture of such a heat­ing device, you should under­stand how it works, and for this, study its device. An indi­rect heat­ing boil­er is a con­ven­tion­al tank with pipes inside. A coolant cir­cu­lates through them.

The heat­ing sys­tem can be the source of heat. Water is sup­plied inside the tank, grad­u­al­ly heat­ing up to a tem­per­a­ture deter­mined by the para­me­ters of the coolant. Since water is tak­en for house­hold needs from the top of the tank, its tem­per­a­ture remains sta­ble, it is con­ve­nient to use heat­ed water.

Device diagram

Thus, it is pos­si­ble to pro­vide a pri­vate house, where there is a heat­ing sys­tem that oper­ates on any type of fuel, with hot water in suf­fi­cient quan­ti­ties. An indi­rect heat­ing boil­er can also be used in mul­ti-storey build­ings by con­nect­ing it to the heat­ing sys­tem.

True, it will func­tion only dur­ing the heat­ing sea­son. In order for the device to be used in the absence of heat­ing, an elec­tric heat­ing ele­ment is added to the design, includ­ing it in the net­work as need­ed.

Types of homemade indirect heating boilers

In the most pop­u­lar design option, a coil made of a met­al pipe is used to pass the coolant. The coil is placed in a tank, the tank is filled with water, and then the coolant is passed through.

DIY indirect heating boilerUpon con­tact with the coil, cold water in the tank heats up. If the pipes with the coolant are placed along the walls of the tank, the stor­age boil­er will not work worse.

Home crafts­men are con­stant­ly com­ing up with new device designs. There is an option that allows you to do with­out pipes for the coolant. In this case, two con­tain­ers with dif­fer­ent diam­e­ters are used. They are insert­ed into each oth­er, cold water is sup­plied to the small­er one, and the coolant is giv­en a place between their walls.

How­ev­er the use of a coil gives faster heat­ing of water, since a pipe of this shape is longer, and this makes it pos­si­ble to use the coolant more effi­cient­ly. There are oth­er designs, but the above are the eas­i­est to make your­self.


Draw­ings of an indi­rect heat­ing boil­er

Materials and parts required for the manufacture of a boiler

First of all, you need to choose a con­tain­er for the man­u­fac­ture of the tank. The best mate­r­i­al choice is stain­less steel. You can use a ready-made bar­rel, order a tank of the required size, or pur­chase a gas cylin­der. It has suf­fi­cient strength, suit­able dimen­sions and shape. Anoth­er option for mak­ing a tank can be a con­tain­er made of heat-resis­tant plas­tic.Capacity

Holes of the required size should be made in the tank. Two holes will be need­ed to con­nect the cold and hot water sup­ply pipes. One of them is made at the bot­tom of the tank, and the oth­er at the top. Two more holes will be need­ed for mount­ing the coil, designed for the pas­sage of the coolant.


For coil man­u­fac­tur­ing a brass or cop­per tube is per­fect. These mate­ri­als trans­fer heat well, and they are quite eas­i­ly giv­en the nec­es­sary shape. You can also use small diam­e­ter plas­tic pipes.

In order to make a coil, a pipe of the required length is wound on a base, which can be a strong met­al pipe or a round­ed log.

In order for the tube intend­ed for the coil to be bent even­ly, with­out creas­es, it is com­plete­ly filled with sand before start­ing work. Then the coil will turn out to be of the cor­rect shape, of the same diam­e­ter along its entire length.

Often, novice crafts­men do not know how to cor­rect­ly cal­cu­late the dimen­sions of the coil. Its para­me­ters depend on sev­er­al fac­tors — the vol­ume of the tank, the mate­r­i­al of the coil and the tem­per­a­ture of the coolant should be tak­en into account. It’s believed that for every 10 liters of water vol­ume for heat­ing, 1.5 kW of ther­mal pow­er is required.

Based on the vol­ume of the tank, the tem­per­a­ture of the coolant and the tem­per­a­ture of the incom­ing water, the required length of the coil is cal­cu­lat­ed. To do this, use a spe­cial cal­cu­la­tion for­mu­la. For a tank with a vol­ume of 200 liters, when using a coil with a diam­e­ter of 10 mm, its length will be about 15 meters.

Even before the instal­la­tion of the stor­age boil­er, it is nec­es­sary to decide how its ther­mal insu­la­tion will be car­ried out. It will not be pos­si­ble to do with­out it, since nat­ur­al heat loss­es are large and the effi­cien­cy of the water heater will be too low. The ide­al way to insu­late the tank would be to place it inside a suit­able con­tain­er, and then fill it with polyurethane foam.

To assem­ble the boil­er, you should take care of the pres­ence of fit­tings, nuts, rub­ber seals, ball valves. When man­u­fac­tur­ing a struc­ture from a gas cylin­der, weld­ing equip­ment will be required.

Watch a video on how to make an indi­rect heat­ing boil­er with your own hands:

Mounting order

Instal­la­tion of an indi­rect heat­ing boil­er, in which the coolant is sup­plied through the coil, begins with its instal­la­tion. A thread is cut at the ends of the coil, onto which a lock nut is screwed, and then they are insert­ed into the pre­pared holes in the tank so that the lock nuts have a stop.

The thread­ed por­tion of the coil must extend beyond the sur­face of the tank. Rub­ber gas­kets are put on them, and thread­ed cou­plings are screwed on top of them. As a result of these manip­u­la­tions, the coil is secure­ly fixed, while it becomes pos­si­ble to con­nect it to the heat­ing sys­tem.

Wiring diagram

The next stage of work is to con­nect the tank to cold water and drain the hot water tap to the required place. The final part of the instal­la­tion will be the insu­la­tion of the water heater, but before that you should check the tight­ness of all con­nec­tions.

Thus, you can pro­vide your home with enough hot water at min­i­mal cost. The cost of pur­chased mate­ri­als will cost a small amount, espe­cial­ly when com­pared with mod­els made in an indus­tri­al way. The price of a fac­to­ry-made boil­er starts from 200 $ for Draz­ice OKC mod­els.

Video on how to prop­er­ly con­nect an indi­rect heat­ing boil­er with your own hands:

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