How to choose a combined gas and wood boiler

Selecting the ideal heating system for your house is an important choice that will affect both your comfort level and your energy costs. You’re on the right path to effective and adaptable heating if you’re thinking about getting a combined gas and wood boiler. By combining the sustainability of wood with the dependability of gas, these systems provide the best of both worlds. Navigating through the options, though, can be daunting. We’ll go over the important things to think about in this guide when choosing a wood-and-gas boiler for your house.

Priority one should be given to comprehending the operation of a combined gas and wood boiler. Because of their dual fuel capability (wood and gas), these boilers are efficient and versatile. Wood offers a renewable and possibly less expensive alternative to gas, which is readily available from utility providers and consistently provides heat. Homeowners can combine these two fuel sources to reap the benefits of each and guarantee dependable heating all year long.

It is crucial to evaluate your heating requirements before settling on a particular model. Think about things like your home’s size, the local climate, and how much hot water you need. A professional evaluation can assist in figuring out how much heating capacity your space actually needs, allowing you to choose a boiler that will suit your needs without going overboard with unnecessary size.

Another important factor to consider when selecting a combined gas and wood boiler is efficiency. Seek for models that have high energy efficiency ratings, as these indicate how well they can convert fuel into heat. Over time, this results in lower energy bills as well as a smaller environmental impact. Furthermore, certain boilers come equipped with programmable controls and modulating burners, which enhance comfort and efficiency even more.

You should consider installation and maintenance requirements when making decisions. Combination gas and wood boilers have many advantages, but for optimal performance and safety, professional installation is necessary. Regular maintenance is also necessary to keep the system functioning properly and avoid future expensive repairs. When comparing different boiler options, take into account the accessibility of qualified technicians in your area and the ease of finding replacement parts.

Choosing a combined gas and wood boiler for your home heating needs requires careful consideration to ensure optimal performance and efficiency. These versatile systems offer the benefits of both gas and wood heating, providing flexibility and cost savings. When selecting a boiler, factors such as size, efficiency ratings, fuel availability, and installation requirements should be taken into account. Assess your heating needs, consider your budget, and research reputable brands to find the right boiler for your home. Additionally, consulting with a qualified HVAC professional can help you make an informed decision and ensure proper installation for long-term reliability and comfort. By choosing the right combined gas and wood boiler, you can efficiently heat your home while reducing energy costs and environmental impact.

What are the combined boilers "gas-wood"

Mixed-type boilers, which run on both gas and solid fuel, are always floor-constructed and have dimensions that match those of standard solid fuel models. These are traditional solid fuel boilers that operate without the need of a gas burner. They burn coal, pellets, peat, and anthracite in addition to wood. Similar to single-fuel boilers, universal boilers are strapped, installed, and connected.

What they are used for and how they are used

As we’ve already stated, buying a gas-solid fuel boiler is not financially or practically justified in the absence of special circumstances.

First off, buying gas and solid fuel boilers separately will cost you 90% less in total than buying the combined model. Boilers that use "gas-firewood" cost between 19,000 and 35,000 rubles, and the price of the gas burner is not included in this amount; it needs to be bought separately. There are very seldom ready assemblies that come with a gas burner already installed in the kit. The burner will set you back an additional 6–12k on average. rubles.

The cheapest simple boilers on the market for heating a private residence

Second, standalone single-fuel models are nearly always more functional and efficient than combined models. When burning natural or liquefied (cylinder) gas, the typical design of solid fuel boiler exhibits the lowest efficiency (at best up to 85%), whereas even low-cost gas boilers have an efficiency of 88-92%. Likewise, this results in reduced consumption with an equivalent heat output. Additionally, no functional automation is present in combined gas and wood boilers, not even in low-cost gas models.

Third, having two single-fuel boilers has the small benefit of having the second boiler available for use as a backup in the event that the first breaks down.

On the other hand, there are instances where investing in a universal boiler that runs on wood and gas can be more advantageous. As an illustration:

• with access to any of the types of solid fuel for a symbolic price. When solid fuel reserves are exhausted, stable combustion without human intervention is required, or a previously unavailable gas main is installed near the house, it is always possible to switch to a gas burner;
• If the area of the house is rather small and allocate at least 8 sq. km. м. areas under separate single-fuel boilers is impossible.

Device and principle of operation

These boilers have a conventional design where solid fuel is burned in the furnace chamber and a heat exchanger is located within, with coolant circulating throughout the system. The fuel is inserted via the front door, and the ash is gathered in the bottom ash drawer.

In the event that switching to gas becomes necessary, a gas burner is mounted on the ash pan door or a specially designated mount using the proper fastening (without welding). Nevertheless, when burning gas, the heat exchanger’s large furnace chamber design accumulates significantly less heat energy; its efficiency only stays between 75 and 85%, similar to what happens when burning high-quality solid fuel.

Additionally, there are sophisticated hybrid models available that have two furnaces that can burn fuel simultaneously. The combustion chambers are divided by a small ash box and heat exchanger construction. The lower combustion chamber typically has a gas burner while the upper combustion chamber typically burns solid fuel. These models, however, run between 200 and 350 thousand rubles in price. rubles.

Boilers that can burn a single fuel deposit for up to seven days

Reviews of universal boilers on solid fuel and gas: advantages and disadvantages

How to choose a combined boiler unit

When selecting a tt model, the selection criteria are nearly identical. It is required to ascertain using:

1. Number of circuits. Single-circuit models are more common, they heat only the heating circuit. Two-circuit models are also capable of heating sanitary water (it is not mixed with service water from the heating circuit). Two-circuit models are more expensive by 10-40%, but it is still the cheapest way to organize hot water supply in the house.
2. Fuel burned. Basically, combined boilers are designed to burn both hard coal and charcoal, firewood, pellets, peat. Models with a cast-iron heat exchanger are capable of burning anthracite. But some boilers are designed only for firewood. Types of fuel are always described in the technical specifications or boiler passport.
3. Material of the heat exchanger. There are two options: steel or cast iron. Steel heat exchangers are inexpensive to produce, lightweight, resistant to temperature fluctuations and mechanical damage, but have thin walls and are not resistant to corrosion, their service life on average 12-15 years. Cast iron heat exchangers are heavy, have thick walls, do not corrode and last more than 30 years, but are used in more expensive models.
4. Operating pressure. Some models are designed for working pressure in the system is not higher than 1 bar, which implies the impossibility of use in closed heating systems with forced circulation, where the working pressure is usually 1.5-2 bar.
5. EFFICIENCY. Not the most informative indicator when burning solid fuel, because it strongly depends on its quality (dryness and species of wood, ash content and calorific value of coal). However, when using a gas burner, 4-5% efficiency can recoup the higher cost in one heating season. Optimum efficiency is 80% and above.

Minimum required power

The minimal power needed for a typical uninsulated or inadequately insulated home in the Moscow region with two bricks of masonry and a ceiling height of 2.7 meters is determined using the following straightforward formula: 1 kW for every 10 square meters. Additionally, a 20–30% power reserve is advised.

For instance, the minimum required power of heating equipment for the above-average house with an area of 100 m 2 is 100/10 * 1,3 (30% reserve) = 13 kW. Since there are no boilers with this capacity available on the market, we round up to the next higher value, which is 14 or 15 kW.

Additionally, it is advised to add an additional 10% to 15% to the result when purchasing a two-circuit boiler because the heating circuit is not heated while heating hot water. 13 kW total plus 1,1% reserve = 14,3 kW. Correction factors are applied, which can alter the result by 5–30% upwards or downwards, if the house is well-insulated, has high ceilings, or has a large area of glazing. It can also be located in the country’s southern or northernmost regions.

How to compute the necessary boiler output precisely Formula, correction factors, and individual calculations

The best known manufacturers and models: characteristics and prices

Teplodar Kupper OK 15

The most well-known domestic combination boiler, which can run on natural gas (with a burner installed), coal, wood, or pellets. characterized by a successful design, long-term dependability at a low cost, and simplicity in maintenance. It is also important to note that there are 6 kW blocks of heating elements that you can use to keep the coolant warm long after the solid fuel has burned through completely at night. The owners also comment on the build quality and rather nice, stylish design.

There are, however, a good number of drawbacks as well, including a small loading aperture and the furnace itself (which can only hold wood up to 35 cm), a steel heat exchanger, a relatively low efficiency, and a high soot formation rate.

Viadrus Hercules U22 D-4

One of the most popular and best "gas and wood" combination boilers for heating a private home. The cast iron heat exchanger in the Czech model is known for its durability and ease of use, which are attributed to its high-quality build and alloys. The boiler is completely omnivorous, has an ideal firebox size (fits wood lengths of 40–45 cm), is reasonably efficient (80%), and is both small and elegant in appearance.

Owners’ reviews indicate that a strong closed draught damper is typically associated with abundant soot formation. Because cast iron construction can weigh up to 250 kg, depending on the power variation, installation requires a reinforced floor, and transportation requires a minimum of three people. Another relative drawback of the Czech model is its cost.

Roda Brenner Classic BCR-04

Another nearly identical Czech combination boiler featuring a cast iron heat exchanger and an advanced, effective, and useful design. A layer of thermal insulation separates the body and helps to keep it relatively cool by minimizing heat loss through the boiler modules. Czech dependability, sensible operation and cleaning, and high efficiency are all other characteristics.

After more than six years of operation, no flaws or malfunctions have been found, based on installation experience and owner feedback. Notable is only the price, which is still too high for the typical Russian buyer.

53 000–55 000 rubles is the cost.

GEFEST VPR KSTGV-20

Compact and reasonably priced domestic two-circuit combined boiler. It is distinguished by a good efficiency of 80%, which is made possible by the heat exchanger’s superb design. While the secondary heat exchanger (for DHW) is made of copper, the primary heat exchanger is made of steel. comes almost always with a "BRAY" gas burner in the factory, which is a well-known simple Italian automation SIT.

Please be aware that there is only a single bar of maximum permitted operating pressure. It’s also important to note that the model is not very common in sales.

23 500–26 400 rubles is the cost.

Karakan 20 TEGV

One more two-circuit domestic model. Its design is as simple as it can be, it runs without fuel, it has a big loading aperture and furnace, and it comes with a block of heating elements pre-installed from the factory.

Nevertheless, the heat exchanger is made of steel, has a 75% efficiency rating, weighs 101 kg, and can only operate at a maximum pressure of 1 bar. Over five years of operation and no service complaints.

Prices: summary table

How to select a gas burner for a solid fuel boiler

Because they have a very straightforward screw fixation, universal gas burners for solid fuel boilers are appropriate for all boilers and are not dependent on the factory accessories of particular models. The burners made for a particular model range are the exception. Typically, the burners are made by the same company as the boiler. It is stated in their name or features, for instance, "…for Teplodar boilers."

Selecting a boiler that combines wood and gas can have a big impact on how efficient and comfortable your house is. It provides flexibility and dependability with the versatility of two fuel sources. There are a few important things to consider when choosing a boiler to purchase.

Prioritize and evaluate your heating needs first. Which is more important to you: convenience, environmental impact, or cost-effectiveness? Determining the best boiler model for your house will be made easier if you know what you need.

Next, think about the boiler’s effectiveness and performance. Seek out models with low emissions and high energy efficiency ratings. In the long term, this lowers your carbon footprint and lowers your energy costs.

Don’t forget to consider the cost and accessibility of local fuel sources. The cost of wood and gas can differ based on where you live, so find local suppliers and compare costs to make sure it’s accessible and affordable.

Additionally, take into account the boiler’s installation and maintenance needs. Choose a model that will require less time to install and maintain to reduce downtime and potential repair costs. Maintaining your boiler regularly is essential to extending its lifespan and guaranteeing peak performance.

Lastly, don’t overlook the importance of safety. Select a manufacturer who has a solid reputation for creating safe and dependable boilers. To avoid any safety risks, make sure the installation is completed by trained experts.

In summary, careful consideration of a number of factors is necessary when choosing a combined gas and wood boiler, including your heating needs, efficiency and performance, fuel availability, installation and maintenance requirements, and safety concerns. You can make an informed choice that improves the comfort, effectiveness, and sustainability of your home heating system by carefully weighing these factors.

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