Stove with a water circuit for home heating

In many private houses, wood heating and stoves remain a priority. Someone has a metal stove, someone has a brick one, but one thing unites them - this type of heating is not the most convenient. Too much focus and little comfort. Output - stove heating with a water circuit.

Stove heating with a water circuit - an opportunity to combine tradition and comfort

First, let's understand the terminology. When they say "stove", most often they mean a heating device made of bricks, which is fired with wood. But often this is also called a metal stove with wood or coal. The principles of operation for brick and metal units are the same, the method of heat transfer is changing. Metal has a more convective component (most of the heat is carried by air), while brick is dominated by thermal radiation - from the walls of the furnace and heated walls of the house. This article is mainly about brick ovens, but most of the information can be applied to metal wood (coal) units as well. Stove heating with a water circuit can be made on the basis of any kind of stove.

Conventional stove heating: advantages and disadvantages

In our country, houses were traditionally heated with brick stoves, but gradually this type of heating was replaced by water systems. All this is because, along with the advantages, a simple stove heating has a lot of disadvantages. First, about the merits:

• The stove transfers most of the heat by thermal radiation, and it, as scientists have found, is better perceived by our body.
• A Russian or some other heating stove has a colorful appearance, it is often possible to observe an open flame.
• You can make a brick oven with chimneys for a more complete use of the generated heat.
• Heating of this type is non-volatile - it does not depend on the availability of electricity.
• There are models of stoves for heating the second floor (due to the heating panel with smoke channels).
  

  Stove heating

Today stove heating is perceived more as exotic, since it is very rare. It cannot be argued that it is very pleasant to be near a warm stove. A kind of special atmosphere is created. But there are also many serious disadvantages:

• Uneven heating - hot near the stove, cold in the corners.
• Large area occupied by the oven.
• Heated only those rooms into which the walls of the stove go.
• The inability to regulate the heating temperature in individual rooms.
• Low efficiency. For conventional stoves, 60% is already a very good indicator, while modern heating boilers can produce 90% or more (gas).
• The need for frequent maintenance. To melt, adjust the dampers, clean out the coals - all this regularly and constantly. Not everyone enjoys it.
  

  The principle of organization of smoke flows - horizontal and vertical

As you can see, the disadvantages are significant, but some of them can be leveled out if a heat exchanger is built into the furnace, which is connected to a water heating system. Such a system is also called stove water heating or stove heating with a water circuit.

Water stove heating

When organizing water heating from the stove, a heat exchanger (water circuit) is built into the firebox, which is connected to radiators with pipes. A coolant circulates in the system, which carries heat from the stove to the radiators. This solution increases the comfort of living in the winter.The thing is that radiators can be installed in any room, that is, the stove can stand in one room, and all other rooms will be heated by batteries, through which heated water runs.

Stove heating with a water circuit: an example of a system with a hot water storage (boiler)

At the same time, the remaining disadvantages of stove heating remain, but the advantages of water heating are added - you can adjust the temperature in each room (within certain limits), a large inertia smooths out the unevenness of the temperature regime. By the way, the same scheme works with metal stoves with wood or coal.

System types

There are two types of hot water heating systems: forced and natural circulation (EC). Natural circulation heating is non-volatile (electricity is not required for operation), coolant circulates through natural physical processes. The disadvantage of this heating method is the need to use pipes of a large diameter, that is, the volume of the system will be large and will have great inertia. When lighting the stove, this is not very good - it will take a long time to warm up. But after burning out, the house remains warm longer.

Another disadvantage is that to create conditions for the movement of the coolant, the supply pipe is raised up - to the ceiling or to the level of the radiators (in extreme cases). When heating a two-story house, the pipe goes up from the boiler, spreads through the radiators, and then goes down and bypasses the batteries on the lower floor.

The simplest scheme of systems with natural circulation

Another important drawback is the relatively low efficiency of heating systems with EC - the coolant moves slowly, carries little heat.

Stove heating with a water circuit and forced circulation is characterized by the presence of a circulation pump (pictured below) that runs constantly. Its task is to drive water at a certain speed. By changing this speed, you can change the intensity of space heating. This leads to the fact that, other things being equal, such heating is more efficient. But for the system to work, power is needed - the pump must work constantly. When it stops, the system boils and fails. If power outages occur rarely, it is enough to haveuninterruptible power supply with a set of rechargeable batteries. If the light is turned off often and for a long time, you will also have to install a generator, and the total cost of such a solution is considerable.

Furnace heating scheme with a water circuit and a circulation pump

There is also a third type of system: mixed or combined. Everything is designed for natural circulation, but a circulation pump is installed. As long as there is electricity, heating works as forced (with a pump), when the light is turned off, the coolant moves on its own.

Heat accumulator

Since the stove is not constantly heated, but has a cyclical operation algorithm, it is hot or cold in the house. And the presence of radiators does not save much from this. Although the differences are not so critical, they are still there. Especially there is not enough heat at night, and I really do not want to get up and drown. To solve this problem, a powerful oven is installed, and a heat accumulator is built into the system. This is a large container filled with coolant that stands between the stove and the heating system.

Stove heating with a water circuit and a heat accumulator

That is, there are two separate independent circuits. The former transfers heat from the oven and is usually done with natural circulation. The second drives the coolant into the radiators, and there is usually a circulation pump.

This method of organizing water stove heating is good in that while the stove is heated, the water in the tank is actively heated. With the correct calculation, it heats up to 60-80 ° C, which is enough to maintain the normal temperature of the radiators for about 10-12 hours. At the same time, there is neither particular heat nor extreme cold. The atmosphere is quite comfortable.

Installing a heat accumulator in the system (sometimes also called a buffer or buffer tank) also reduces the risk of the system boiling. The second circuit will definitely never boil, but so that the first does not boil, it is necessary to correctly calculate it - so that even in the mode of natural circulation, the coolant moves at a sufficient speed and does not have time to overheat.

Oven register

To heat the coolant, a water circuit is built into the furnace (also called a register, heat exchanger, coil, water jacket). Its shape can be any, but most often they make rectangular flat containers or a set of pipes connected into a single system (such as radiators).

One example of a water circuit for a furnace

To connect the heat exchanger to the system, two nozzles are welded into it: one on top for hot water intake, the second on the bottom for pumping cooled water from the return pipeline.

Questions often arise with the sizing of the water circuit for the furnace. It can be roughly calculated based on the heat loss of the building. It is believed that to transfer 10 kW of heat, a heat exchanger area of ​​1 sq. m. But at the same time it is necessary to take into account the operating time of the furnace - after all, it is not constantly heated. It's not very cold yet - once a day for about 1.5 hours, when it's cold - twice. During this time, it is necessary for the stove to have time to heat all the water in the heat accumulator. Therefore, the calculation of the area of ​​the heat exchanger is based on the daily amount of heat required to compensate for heat loss.

For example, let the heat loss for a house be 12 kWh. It will be 288 kW per day. The stove is heated, let it be 3 hours, all the necessary heat must accumulate during this time. Then the required power of the water circuit for the furnace is 288/3 = 96 kW. To convert it to area, we divide by 10, we get that for these conditions the register area should be 9.6 m2. Which form you choose is up to you. It is important that the outer surface of the register is no less.

Furnace construction around the heat exchanger

Well, a couple more points. First, the capacity of the furnace must be greater than the found capacity of the heat exchanger. Otherwise, the required amount of heat will simply not be released. The second nuance: the capacity of the heat accumulator must also correspond - it must be more by about 10-15%. In this case, boiling of the coolant is excluded.

Just remember that the heat capacity of water and antifreeze is very different. The accumulator with antifreeze as a heating medium must be significantly larger than the water tank (in the same system).

What else is worth remembering that it is advisable to insulate the heat accumulator well - so that the heat remains longer. In this case, stove heating with a water circuit will be even more economical.

Is it possible to install a register for heating in an existing furnace

It is more correct, of course, to build a furnace around a manufactured register. But, if the stove is already standing, a water circuit can still be built into it. True, you will have to try hard - they are of considerable size and still have to hold on in some way. So the task is not easy. In addition, do not forget that you still have to make two conclusions - to connect the supply and return pipelines.

The best option is to make a water jacket in the shape of an oven (this one is for a metal one with burners)

It is also not very easy to find a place for the register. Its direct contact with fire is very undesirable, but it must be in an environment of hot gases. In this case, one can hope that the heat exchanger will last a long time.