Which boiler is better to choose
Let's try to compare a single-circuit boiler with a double-circuit one and find out which one is better to choose for your home.
A double-circuit boiler with one heat exchanger, especially bithermic, is an excellent solution when it is important to rationally use every centimeter of space. Where this issue is not so acute, it is better to give preference to a double-circuit boiler with separate heat exchangers
An indirect heating boiler must be connected to a single-circuit boiler for organizing hot water supply, and this will require additional space, and the cost of a single-circuit boiler in conjunction with a boiler is higher than the cost of a double-circuit boiler with similar parameters. But, like any storage water heater, an indirect heating boiler connected to a single-circuit boiler also has advantages over an instantaneous water heater, which is part of a double-circuit boiler.
The temperature of the hot water from the boiler does not depend on its consumption, while the temperature of the water from the instantaneous heater may change because of this, especially when several consumers are turned on at the same time. Just keep in mind that when the hot water in the boiler runs out, it will take time for it to heat up again. Therefore, it is necessary to calculate in advance what volume of the boiler will be optimal for uninterrupted hot water supply in specific conditions.
Double-circuit boiler - for a small country house
So, the main advantage of double-circuit boilers is space saving, the main disadvantage is the instability of the hot water temperature while turning on several consumers at the same time. Therefore, a double-circuit boiler will be the best solution for a small country house.
Single-circuit boiler with a boiler - for a large cottage
A single-circuit boiler, together with a boiler connected to it, will take up more space, but such a design is able to consistently provide several water points with hot water. Therefore, in a large cottage or capital house, where friends or relatives can come and where hot water may be simultaneously required in the kitchen and in the shower room, and saving one or two square meters of space is not significant, it is better to use a single-circuit boiler in conjunction with an indirect heating boiler.
A gas boiler is an autonomous heating device, which is one of the most popular and convenient solutions for organizing heating and hot water supply in a private house. There are two types of boilers - single-circuit and double-circuit. The first in the basic version are intended exclusively for heating. While double-circuit ones also solve the problem of heating water. Let's take a closer look at the principles of operation and the differences between wall-mounted boilers.
What is the difference between single-circuit gas boilers and double-circuit boilers
When choosing which is better, a single-circuit or double-circuit boiler, you should study the principle of operation, the similarities and differences of each type well:
- Single loop design - high performance. As a heat exchanger, a flow coil or “water jacket” made of cast iron or steel is used.
- A device with two circuits - a heat exchanger around the perimeter surrounds a coil connected to a hot water supply system or an indirect heating boiler built into the boiler body.
The difference between a heating boiler with two circuits and a boiler with one circuit lies in the purpose. Models without a built-in 2nd circuit are made exclusively for heating, but with the possibility of additional conversion for hot water supply through an external boiler.Equipment with two circuits, able to simultaneously work for the heating system and hot water.
Which boiler is more profitable - double-circuit or single-circuit
Comparative gas consumption during the operation of single-circuit and double-circuit boilers shows that the first models are more economical. But, this is valid only under optimal conditions, without taking into account the costs of installing and connecting an indirect heating boiler.
Several factors are taken into account when considering economy:
- Specifications for units with two circuits. For heating equipment, the technical documentation indicates the throughput. This parameter indicates how much hot water will be heated per minute. Typically, the coefficient is 10-15 liters for units using instantaneous heating, and 45-60 liters for models with a built-in buffer tank. If this volume is not enough, you will need to install an external storage tank.
- The cost of connecting the storage tank. A boiler costs from 40 to 80% of the cost of a gas heat generator (depending on the model chosen).
- Gas costs - single circuit design, consumes less gas, working exclusively to heat the heating system. After connecting the boiler, additional costs, 10-20%, will be required for heating and maintaining the temperature of the water in the tank.
Therefore, equipment with a single circuit is more economical, but only if it is planned to use the selected model of heating equipment, strictly for its intended purpose. Connecting the boiler makes its own adjustments and makes the design with two circuits more economical.
Which gas boiler is better to choose - single-circuit or double-circuit
The difference between a single-circuit gas boiler connected to an indirect heating boiler and a 2-circuit one is that the first type of heat generator is not limited by the amount of heated water for hot water supply. The storage capacity is selected individually, depending on the needs of the residents of the house.
The choice between single-circuit and double-circuit heating boilers is easy to make if you understand well whether it will be necessary and how much hot water is required at the outlet. If hot water is not provided or a large volume of heated water is required, it is better to install a unit with a single circuit.
For simultaneous connection to a hot water supply and a heating system, with a cost of not more than 60 l / min, a 2-circuit model with a heat exchanger and a DHW coil is installed.
About the advantages of condensing boilers
Image 6. Scheme of operation of two heat exchangers: A - heating supply line, B - cold water inlet, C - hot water outlet, D - heating return line, 1 - heat exchanger, 2 - shut-off screws, 3 - three-way valve, 4 - secondary heat exchanger , 5 – primary heat exchanger.
Before making a choice among traditional boilers, it is advisable to get acquainted with the advantages of a condensing boiler. The main disadvantage of this boiler is the formation of condensate, which must be removed, that is, it will be necessary to create a sewer. But if the house already has a sewerage and water treatment system, then there should be no problem with removing condensate. Such designs have a fairly high rating.
Figure 7 explains in a very accessible way how to increase the efficiency of this type of boiler. On the left side, all types of losses in a conventional apparatus are shown and 10% (this is approximately) of the heat leaving with water vapor (latent heat) is separately allocated. Without taking into account losses with outgoing water vapor, 92% of the heat obtained from gas combustion is usefully used.
In order to keep the latent heat inside the boiler, it is necessary that some surface with which the combustion products that escape into the atmosphere come into contact has a temperature below 55 ° C. And the lower the temperature, the more efficient the boiler.
It is at this point that attention should be paid
Image 7. Scheme of condensing boilers.
The surface inside the combustion chamber, which may have a specified temperature, may be formed from the heat transfer fluid coming after heating the space. If the coolant has a temperature of more than 55 ° C, then there will be no effect from such an expensive acquisition.
If, when purchasing such a device, the seller says that its efficiency is more than 100%, do not refuse the purchase, deciding that you are simply being deceived. Do you know for sure that the efficiency of more than 100% does not happen? How the efficiency turns out to be more than 100% can be seen from the right figure in image 7. In reality, it is equal to 98%.
Before purchasing a condensing boiler, make sure that the temperature in the heating system can be below 55°C.
When choosing one or another option for space heating and hot water supply, you cannot choose only between single-circuit or double-circuit options. It is necessary to take into account the advantages and disadvantages of the options for the used combustion chambers, chimneys, room requirements and other factors.
Particular attention should be paid to the possibility of installing a condensing apparatus. Rest assured that it will pay off over time.
