Two schemes of the DOS of a suburban private house – which one to choose?

Selecting the appropriate heating scheme is one of the most important choices you’ll have to make when designing a private home in the suburbs. This important decision will affect your home’s comfort, energy efficiency, and long-term expenses. Making an informed choice requires an understanding of the two main schemes, given the multitude of options available.

The first plan uses a conventional boiler-based system, which is a dependable and well-established technology. With this technique, water is heated in a boiler and then pumped through underfloor heating pipes or radiators. Many homeowners rely on this tried-and-true system because of its effectiveness and efficiency.

However, there is also the more recent heat pump system. This option offers an environmentally friendly and possibly more affordable solution by using cutting-edge technology to extract heat from the ground, air, or water. Even though there may be a larger upfront cost, the long-term advantages of lower environmental impact and energy savings make it a desirable substitute.

Taking into account a number of factors, such as your household’s unique needs, budget, and environmental preferences, is necessary when choosing between these two schemes. We’ll go into the specifics of each system in this post, outlining the benefits and drawbacks so you can make the best heating decision for your suburban house.

Scheme 1: Centralized System	Scheme 2: Decentralized System
All rooms are connected to a single control unit, making it easier to manage.	Each room has its own control unit, providing individual control.
Installation can be more complex and costly due to extensive wiring.	Easier and cheaper to install with less wiring involved.
Better for larger homes with multiple rooms and high energy needs.	Ideal for smaller homes or areas with varying usage patterns.
More efficient in maintaining a consistent temperature throughout the house.	Allows for more precise temperature control in individual rooms.
Potential for higher energy efficiency and lower bills if used correctly.	Flexibility in usage can lead to energy savings.

Hot water supply scheme with a running water heater

As a water heater that runs, you can use:

• GVS gas column;
• a heating contour of the DOS of a double -circuit heating boiler;
• Electric flow heater of water.
• plate heat exchanger connected to the heating circuit.

When the hot water tap is opened, the instantaneous water heater starts to heat the water as soon as it is drawn.

In the brief time that the water moves through the heater, all of the energy used for heating is transferred from the heater to the water almost instantaneously. The instantaneous water heater’s design allows for limiting the water flow rate, which helps to quickly obtain water at the desired temperature. The instantaneous heater’s water flow rate, or the volume of hot water that flows out of the tap, has a significant impact on the temperature of the water at the outlet.

The instantaneous water heater needs to have a minimum power of 10 kW in order to adequately supply hot water to a single shower head. A heater with a power output greater than 18 kW can fill a bathroom in a reasonable amount of time. Additionally, you will require a flow heater power of at least 28 kW for comfortable hot water use if you open the kitchen tap while filling the bathtub or running the shower.

Generally speaking, a smaller boiler is sufficient to heat an economy class home. As a result, the demand for hot water determines how much power a double-circuit boiler should have.

The following factors prevent the DHW scheme with a running water heater from enabling the home to use hot water comfortably and affordably:

• The temperature and pressure of the water in the pipes are very dependent on the value of the water consumption. For this reason, when opening another tap, the temperature of the water and the pressure in the DIS system change greatly. To use water at the same time even in two places is not very comfortable.
• With a small consumption of hot water, a flowing water heater does not turn on at all and does not warm the water.To obtain water, the required temperature often has to spend more water than it is necessary.
• Hot water from the crane appears with some delay. The waiting time increases as the length of the pipes from the water heater to the water collection point increases. At the very beginning, some of the water has to be uselessly drained into the sewer. Moreover, this is water that has already been heated, but has managed to cool down in the pipes.
• Scaling deposits quickly accumulate on a small surface inside the heating chamber of the instantaneous water heater. Hard water will require frequent descaling.

In the end, the installation of an instantaneous water heater in the DHW system results in an increase in the amount of water used and sewage discharged, an increase in energy used for heating, and an inadequate amount of comfortable hot water use in the home.

Despite its drawbacks, DHW systems with instantaneous water heaters are nonetheless in use because of their small size and affordable cost.

Installing a separate instantaneous water heater close to each location where water is taken will improve the efficiency of the system.

Installing electric flow heaters is practical in this situation. However, these heaters have the potential to use a large amount of electricity from the electrical grid (up to 20–30 kW) when they are drawing water simultaneously from multiple locations. A private home’s electrical system is typically not built for this, and electricity is expensive.

Selecting the best scheme is essential for convenience and efficiency when organizing the DOS (Distribution of Services) for a suburban private home. Centralized and decentralized schemes are two popular types. One advantage of the centralized system is that all utilities can be managed from one location, which can simplify maintenance and possibly save costs. However, a decentralized system offers greater customization and flexibility, guaranteeing that every room in the house has the exact supplies it requires. A person’s budget, lifestyle requirements, and house size are some of the factors that influence their choice between the two. You can make an informed choice by understanding the benefits and drawbacks of each plan with the aid of this article.

How to choose an instantaneous water heater

The amount of water flow that an instantaneous water heater can heat is the primary consideration when selecting one.

It is advised to concentrate on the following hot water consumption volumes at 55 °C at the analysis points for comfortable use:

• from the sink faucet or washbasin 4.2 l/min (0.07 l/sec);
• from bath or shower tap 9 l/min (0.15 l/sec).

One instantaneous water heater is linked to three points of analysis: a kitchen sink, a bathroom sink, and a shower. You need to choose a heater that can supply at least 9 liters per minute of 55°C water, if you only want to fill the bathtub. Additionally, this type of water heater will enable simultaneous use of hot water from the sink and washbasin taps.

If the heater can provide hot water at least 9 l/min + 4.2 l/min = 13.2 l/min, then using hot water in the shower and washbasin simultaneously will be comfortable.

The maximum performance of an instantaneous water heater is typically indicated by the manufacturer in the technical specifications. This performance is based on heating water at a specific temperature difference, dT, such as 25 oC, 35 oC, or 45 oC. This indicates that at maximum performance, water with a temperature of +35 °C, 45 °C, or +55 °C will flow from the tap if the water supply has a temperature of +10 °C.

Exercise caution. Some vendors list the device’s maximum performance in their advertisements, but they "forget" to mention the temperature difference at which that performance is based. Although a gas water heater with a 10-liter-per-minute capacity is available, it only heats water up to 35 оС, or 25 °C, at that flow rate. With a column like that, using hot water might not be very comfortable.

A double-circuit boiler or gas water heater with a maximum productivity of at least 13.2 l/min at dT=45 °C is appropriate for our example. At these hot water parameters, the gas appliance’s power will be roughly 32 kW.

One more factor to consider when selecting an instantaneous water heater is the minimum performance, or flow rate l/min, at which heating is activated.

The water heater won’t turn on if the pipe’s water flow is less than the amount indicated in the device’s technical specifications. It is frequently necessary to use more water than is necessary because of this. Select a device that has the lowest possible minimum capacity—for instance, no more than 1.1 l/min.

The maximum heater power of electric instantaneous water heaters meant for residential use is between 5.5 and 6.5 kW. Water is heated to dT = 25 °C at maximum productivity of 3.1 – 3.7 l/min. A single water point, such as a sink, shower, or washbasin, is served by one of these water heaters.

DHW circuit with storage heater (boiler) and water circulation

A fairly large volume, heat-insulated metal tank is called a boiler or storage water heater.

An electric heating element and a tubular heat exchanger connected to the heating boiler are the two heaters that are typically integrated into the lower portion of the water heater tank simultaneously (diagram for connecting the boiler to the boiler). Most of the time, the boiler heats the water in the tank.

When the boiler is shut off, the electric heater is activated as needed. One common term for this type of boiler is an indirect heating boiler.

In an indirect heating boiler, hot water is used up from the tank’s top. Instead, cold water from the water supply enters the tank’s lower section right away, gets heated by a heat exchanger, and rises to the top.

In the European Union, solar heaters and collectors are mandated for hot water systems in newly constructed homes. An additional heat exchanger is fitted in the indirect heating boiler’s lower section in order to connect the solar collector.

A solar collector heats the water in the boiler. The boiler or electric heater is turned on if the collector is not producing enough heat. View the article "DHW system with solar collector."

DHW circuit with layer-by-layer heating boiler

Hot water is consumed from the top of the tank. In its place, cold water from the water supply immediately flows into the lower part of the tank. The pump drives water from the tank through a flow-through heater and supplies it directly to the top of the tank. Due to this, hot water appears to the consumer very quickly – there is no need to wait until almost the entire volume of water warms up, as happens in an indirect heating boiler.Recently, a hot water supply system with a stratified heating boiler has been gaining popularity, the water in which is heated by a flow-through heater of a double-circuit boiler. This boiler does not have a heat exchanger, which reduces its cost.

Without sacrificing comfort, you can install a smaller boiler in the home and lower the flow-through heater’s power thanks to the top layer of water’s rapid heating.

Double-circuit boilers with an integrated or remote layer-by-layer heating boiler are made by manufacturers. Because of this, the DHW system’s equipment costs and dimensions are marginally lower than those of an indirect heating boiler.

Regardless of whether it is used or not, the water in the boiler is preheated. You can use hot water in the house for several hours thanks to the hot water reserve in the tank.

This makes it possible to heat the water in the tank for an extended period of time, gradually building up thermal energy in the hot water. Thus, the boiler also goes by the name "storage water heater."

The use of a relatively low power heater is made possible by the prolonged heating period of the water.

Storage gas water heater – boiler

In domestic hot water systems, storage boilers—whose water is heated by a gas burner—are less common. It is significantly more expensive to install heating and hot water systems in a home with two gas appliances—a gas boiler and a gas boiler.

Installing gas boilers can be beneficial for homes with central heating or for private residences heated by solid fuel boilers that use liquefied gas to heat the water in the district heating and waterwork system.

Similar to boilers, gas water heaters can be purchased with or without an open combustion chamber, with or without forced flue gas removal and with or without a chimney draft.

Boilers made of storage gas are available that don’t need to be connected to a chimney. (Gas stoves for homes do not require a chimney to operate.) These devices’ gas burners have a modest power output.

Wall mounting is possible for gas boilers up to 100 liters in capacity. Water heaters with large volumes are mounted on the floor.

Gas ignition is used in water heaters in a few different ways: hydrodynamic, electronic, and using a pilot wick.

A tiny flame that is manually ignited first is always burning in devices that use a pilot wick. In this torch, a certain amount of gas burns pointlessly.

Electronic ignition is powered by an accumulator or battery.

When the tap is opened, water flows through a turbine that rotates, initiating hydrodynamic ignition.

How to choose the volume of a storage water heater – boiler

The comfort level of using hot water in the house increases with the storage water heater’s volume. However, the larger a boiler is, the more expensive it is, the more it will cost to maintain and repair, and the more space it will require.

The following factors are taken into account when choosing the boiler’s size.

It is widely acknowledged that a boiler volume of 20 to 30 liters per person will suffice to provide the bare minimum of comfort when using hot water throughout the home.

A boiler, whose volume is chosen at the rate of 30 to 60 liters per user of water, will increase comfort.

A 60–100 liter water heater for each person residing in the home will offer a high degree of comfort.

It is required to use nearly all of the water from an 80–100 liter boiler in order to fill the bathtub.

How to choose boiler power for a DHW boiler

You should consider the boiler’s installed heating element’s power when making your selection. For instance, a boiler heater (heat exchanger, built-in gas burner, or heating element) with a power of roughly 20 kW needs to be installed in order to heat 100 liters of water to 55 oC in 15 minutes.

When the heating is first turned on, the temperature of the water in the boiler is actually equal to the temperature of the water in the water supply. In the future, the water in the boiler is nearly always preheated to a specific temperature. Lower power heating devices are used to bring water to the desired temperature in a reasonable amount of time.

It’s still advisable to find out how long the boiler will take to heat the water, though. To do this, apply the following formula:

The formula is t = m•cw•(t2 – t1)/Q, where t is the water heating time in seconds (s); m is the water mass in the boiler in kilograms (the water mass in kilograms is equal to the boiler volume in liters); cw is the water’s specific heat capacity, which is equal to 4.2 kJ/(kg•K); t2 is the temperature at which the water should be heated; t1 is the boiler’s initial water temperature; and Q is the boiler power, kW.

As an illustration, the time needed to heat 200 liters of water with a 15 kW boiler from 10 °C (assuming the water enters the boiler at this temperature) to 50 °C is 200 x 4.2 x (50 – 10)/15 = 2240 s, or roughly 37 minutes.

DHW diagram with water circulation in the system

The hot water circulation in pipelines can be arranged with the use of a storage water heater in a hot water system. A ring pipeline that continuously circulates hot water is connected to each hot water sampling location.

Each hot water consumption point’s pipe section length from the ring pipeline should not exceed two meters.

A circulation pump makes sure that water is circulated throughout the DHW system. The pump only has a few tens of watts of power.

Certain designs of DHW pipelines allow for the creation of natural water circulation without the need for a pump.

The DHW system’s water circulation ensures that hot water is continuously delivered to the sampling locations.

The water supply mode is more stable in a DHW system that has both water circulation and a storage heater:

• Hot water is always available at the sampling points.
• Water can be collected simultaneously in several places. The temperature and pressure of water change slightly when the flow rate changes.
• You can take any, no matter how small, amount of hot water from the tap.

In addition to improving the comfort of the water supply in hard-to-reach areas of the house, the recirculation circuit enables heated floor circuits in individual rooms to be connected to it. For instance, a water-heated floor in a bathroom will be cozy year-round.

Energy is continuously used in a hot water supply system with water circulation to run the circulation pump and make up for heat losses in the boiler and the water-circulating pipes. Installing a circulation pump with an integrated programmable timer that shuts off water circulation during off-peak hours is advised in order to save energy usage. Insulation surrounds the hot water pipes and boiler.

Disadvantages of a hot water supply system with a double-circuit gas boiler

As you are aware, a double-circuit gas boiler can heat the heating system and supply hot water to a home. The boiler’s flow-through heat exchanger produces hot water.

Frequently, it is discovered that the boiler power needed to produce hot water is much higher than the power needed to heat every room in the house.

Double-circuit boilers have a fairly large maximum power of about 24 kW or more, which is sufficient to heat the required amount of water. The boilers are fitted with automated machinery that can lower the boiler power to a minimum of about 30% of the maximum by varying the burner flame. A double-circuit gas boiler typically has a minimum power of 8 kW or more. In both the heating and DHW modes, this is the lowest boiler power.

A double-circuit boiler’s gas burner cannot run steadily on less power than the minimum (less than 8 kW) due to design features. In addition, the boiler in heating mode frequently needs to produce less than 8 kW of power in order to function with a private home’s heating system or an apartment’s autonomous heating system.

For instance, 8 kW of power is sufficient to heat a house or apartment with an area of 80 to 110 m³, especially during the coldest five days of the heating season. The boiler’s output and power should be much lower during warmer months.

Problems with the adaptation (coordination) of the double-circuit boiler and the heating system occur because the boiler cannot run on less power than the minimum.

The boiler generates more heat than the heating system can handle when it comes to small objects that require little heat to be heated. When there is a discrepancy between the boiler’s and the system’s parameters, the double-circuit boiler enters pulse mode, or "clocking," as it is commonly called.

The service life of boiler parts is greatly shortened when operating in the "clocking" mode, and efficiency is also greatly decreased.

Continue reading "Setting a Double-Circuit Gas Boiler’s Power"

Double-circuit gas boilers have an efficiency of less than 80% when running at minimum power and more than 93% when running at maximum power. Consider the additional reduction in efficiency that would result from forcing such a boiler to run in pulse mode, where the gas burner would constantly relight.

It should be noted that a double-circuit boiler uses very little power when it is heating for the majority of the year. It will literally be a waste of at least 1/4 of the gas used for heating. Include in this the price of replacing boiler parts that wear out too soon. This will cover the cost of installing the house’s inexpensive heating and hot water systems.

With less than 8 kW of heating system power.Installing a boiler along with a 60–120 liter hot water boiler is more cost-effective.

You can install a boiler with a lower maximum power, less than 9–11 kW, if you have a storage boiler. Both the heating and hot water modes will function as efficiently as possible when the boiler works in tandem with it.

For precisely these situations, a number of heating equipment manufacturers create special kits that include a boiler and a built-in or remote boiler. While this equipment will cost more, it will save gas, extend the equipment’s service life, and enable more comfortable hot water use.

But recently, 11 kW or so maximum power double-circuit boilers have been available for purchase. These boilers are made to heat a small amount of water for a single user. The sink and shower are yours to turn on. Using hot water in the sink and shower at the same time will cause issues. It will also take a very long time to fill the bathtub.

Selecting the ideal DOS (Domestic Open Space) plan is essential to establishing a cozy and useful living space in your suburban home. The decision between the two primary schemes ultimately comes down to your own requirements, tastes, and the distinctive qualities of your property.

If privacy is your top priority and you like a more divided design, the conventional compartmentalized plan might work best. This method creates separate spaces for various activities, which can be especially helpful for larger families or people who host guests often. It also creates a sense of order and separation.

On the other hand, an open-plan layout gives a contemporary, airy feel if you value transparency and a smooth transition between areas. This arrangement lets in more natural light and can give your house a feeling of openness and community. It’s perfect for people who like to host guests and need a more adaptable area that can serve a variety of purposes.

The ideal DOS scheme for your suburban home ultimately comes down to striking a balance between practicality and personal preference. Think about your future plans, how you use your space on a daily basis, and how each layout will fit into your lifestyle. You can make an informed choice that improves your home’s usability and enjoyment by carefully considering these factors.

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