Combi Boiler

Wall-mounted and floor-standing Combi Boiler systems are independent heating solutions used for residential units, villas, and office buildings. The types, technical specifications, selection method, capacity calculation, and best prices of combi boilers (with warranty) are presented below.

Combi Boiler (wall-mounted and floor-standing) is a device capable of simultaneously supplying domestic hot water and heating water for radiators for each apartment unit (or villa). A wall-mounted or floor-standing combi boiler can be easily installed in place of a wall or floor cabinet. Compared to central boiler rooms, combi boilers usually offer higher efficiency and energy performance while consuming less fuel.

In addition, using a combi boiler not only eliminates extensive piping systems in the building but also provides independent heating and domestic hot water supply for each unit.
In general, heating combi boilers are classified into two types based on installation method: wall-mounted and floor-standing combi boilers.

7 Key Points for Selecting and Purchasing a Heating Combi Boiler (Wall-mounted, Floor-standing)

1. Measure the floor area of your residential or office unit.
2. Determine the required boiler capacity using the heating capacity calculation method described below.
3. Based on the available fuel type and calculated heating capacity, select the appropriate type and model of the heating combi boiler.
4. According to the available installation space, decide whether a wall-mounted or floor-standing combi boiler is suitable.
5. Check the building’s flue system (vertical to the roof or with a horizontal section). If the flue has a horizontal run, be sure to use a fan-assisted combi boiler.
6. Ensure the supply of fresh air or oxygen required for combustion (for units smaller than 65 square meters).
7. According to Chapter 17 of the National Building Regulations, the minimum approved area for installing a heating combi boiler in residential or office units is 64 square meters. Otherwise, the use of a twin-wall flue or the installation of a fresh air intake vent to supply combustion air from outside is mandatory.

Calculation of Wall-mounted and Floor-standing Heating Combi Boiler Capacity (Gas, Diesel, Dual-fuel, and Electric)

The heating capacity of a combi boiler refers to the effective heating output of the unit and is measured in kilowatts (kW) or kilocalories (KCAL) per hour. This capacity indicates the amount of heat a heating combi boiler can produce within one hour.
Combi boiler capacities vary depending on the heating requirements of the intended space.
Wall-mounted heating combi boilers are commonly available in capacities such as 24kW, 28kW, 30kW, and 35kW, and approximately 20,000, 25,000, 28,000, and 35,000 kilocalories per hour. Based on the design and heating demand of the unit, an appropriate wall-mounted or floor-standing combi boiler can be selected.
There are two common methods for calculating heating combi boiler capacity: the approximate method and the detailed method.

Approximate Method for Calculating Heating Combi Boiler Capacity

To approximately calculate the required capacity of a heating combi boiler (wall-mounted or floor-standing), multiply the floor area by 150 for residential units, by 100 for office units, and by 200 for villas and buildings located outside urban areas. This provides the required capacity of the wall-mounted or floor-standing combi boiler (gas-fired or diesel-fired).

Accurate Method for Calculating Heating Combi Boiler Capacity

In this method, various parameters such as climate conditions, geographical location, unit area, number of occupants, type and thickness of construction materials, number and dimensions of windows and doors, heat transfer coefficients of walls, windows, and doors, as well as the amount of cold air infiltration and air exchange rates, are calculated and considered by HVAC engineers.

These factors are calculated with precision to determine the exact heating load of the unit. Accurate heating combi boiler capacity calculation is typically performed by HVAC engineers or sales experts at the specialized Damatajhiz Group.

Formula for Calculating Wall-mounted and Floor-standing Heating Combi Boiler Capacity

QT=[(U1*A1+...+Un*An)∗ΔT+(V*0.0749*0.24* ΔT)]*4

Where:
• QT = heating load of each unit in kilocalories per hour
• U1 to Un = heat transfer coefficients of each surface between indoor and outdoor areas (BTU/ft².hr.°F), determined based on construction materials using engineering reference tables
• A1 to An = area of each surrounding surface transferring heat to the outside (walls, windows, doors, and roof), measured in square feet
• ΔT = temperature difference between indoor and outdoor conditions (°F)
• V = total infiltrated air volume through door and window gaps (CFH) in ft³/hr
• Constant 0.0749 = air density under standard conditions (Imperial units)
• Constant 0.24 = specific heat capacity of air under standard conditions (Imperial units)

By calculating all parameters in the above formula, accurate results can be obtained for determining the required heating combi boiler capacity for each unit. Note that precise U-values and surface areas must be selected based on the specific characteristics of each building and standard heat transfer coefficient tables.

Note: The thermal energy required for space heating and domestic hot water production in wall-mounted and floor-standing heating combi boilers is not calculated separately. This is because when a hot water tap is opened, the combi boiler temporarily stops space heating and allocates its full heating capacity to domestic hot water production (using a secondary heat exchanger). Once the tap is closed, the system resumes space heating operation.

Types of Wall-mounted and Floor-standing Heating Combi Boilers

Wall-mounted and floor-standing heating combi boilers are available in various designs and capacities. These include fan-assisted wall-mounted models, gas-fired dual and triple heat exchanger units, floor-standing combi boilers with storage tanks, gas-fired, diesel-fired, dual-fuel systems, and fully silent electric combi boilers. As always, selecting the appropriate combi boiler requires determining the correct capacity based on the dimensions and area of the installation site.

At the specialized Damatajhiz Group, technical information for dozens of wall-mounted and floor-standing combi boiler models from reputable brands, all with official warranties, is provided to ensure an optimized and intelligent purchasing experience.

Price of Wall-mounted and Floor-standing Heating Combi Boilers

The price of wall-mounted and floor-standing heating combi boilers varies depending on capacity range, technical specifications, model, and brand. The prices presented by the specialized Damatajhiz Group are up to date and include applicable consumer discounts, as well as the best price guarantee.

Price List of Best-selling Wall-mounted and Floor-standing Combi Boilers

DamaTajhiz: Thousands of products for thousands of projects (since 2004)

Types of Heating Combi Boilers Based on Fuel Type

Heating combi boilers are classified into four types based on the type of fuel used:

• Gas-fired Combi Boiler (wall-mounted and floor-standing, silent operation)
• Diesel-fired Combi Boiler (floor-standing, suitable for installation in boiler rooms or storage areas outside the residential unit)
• Dual-fuel Combi Boiler (floor-standing, suitable for installation in boiler rooms or storage areas outside the residential unit)
• Electric Combi Boiler (wall-mounted and floor-standing, silent operation)

Note: Floor-standing diesel-fired and dual-fuel heating combi boilers are installed and used in boiler rooms of villas and private buildings with yards due to the noise generated by the burner motor and combustion air fan.

What is a fan-assisted Combi Boiler? Combi boilers equipped with an exhaust fan to improve the discharge of combustion gases are referred to as fan-assisted combi boilers. Today, most reputable manufacturers produce and supply wall-mounted combi boilers exclusively as fan-assisted models.

Types of Combi Boilers Based on the Number of Heat Exchangers

• Single Heat Exchanger Combi Boiler: In this type, the heating system water pipe and domestic hot water pipe are separate but are simultaneously exposed to the burner flame, heating the water inside both circuits. This results in rapid hot water production and reduced boiler wear due to pump inactivity during summer. However, scale formation is higher compared to double heat exchanger models, and hot water temperature fluctuations may occur.

• Double Heat Exchanger Combi Boiler: These models include one heat exchanger for the heating system and a separate plate heat exchanger for domestic hot water supply. The heating circuit water is directly exposed to the burner flame, while domestic hot water is heated indirectly through the plate heat exchanger. As a result, hot water is delivered at a stable temperature with significantly lower scale buildup compared to single heat exchanger combi boilers.

This classification is based on the number of heat exchangers used in wall-mounted heating combi boilers. Other features and characteristics may also vary depending on the model.

What Is a Condensing Combi Boiler?

A condensing combi boiler is a new generation of heating systems designed to optimize energy consumption. These units use a secondary heat exchanger to recover latent heat from hot combustion gases. In conventional boilers, this heat is lost through the flue along with water vapor. However, in condensing combi boilers, the water vapor in the exhaust gases condenses into liquid as the temperature drops, releasing additional thermal energy. This recovered heat is used to preheat the incoming cold water, significantly increasing the overall efficiency of the heating combi boiler.

This intelligent process allows condensing combi boilers to consume up to 30% less gas compared to conventional models. Their high efficiency (sometimes reaching up to 110% under ideal conditions) not only reduces energy costs but also helps protect the environment by lowering greenhouse gas emissions. Despite higher initial costs and the need for a condensate drainage system, condensing combi boilers represent a cost-effective and sustainable long-term investment.

Technical Tips for Purchasing and Using Wall-mounted and Floor-standing Combi Boilers

1. Some heating combi boiler models are equipped with an anti-freeze protection system, which requires the boiler to be connected to electricity in order to function.
   - Single-phase electrical connection
   - Minimum system and boiler water pressure must be 1 bar according to the pressure gauge
   - Gas connection (these models can also be installed outdoors)
2. If the combi boiler is installed in open areas such as balconies, patios, or yards, fan-assisted combi boilers equipped with an anti-freeze system must be used. Note that the anti-freeze system operates only when the boiler is connected to electricity and set to at least the minimum operating temperature.
3. Double heat exchanger heating Combi Boilers are recommended when the incoming water has high hardness (mineral content) or when the apartment area exceeds 120 square meters.
4. Fan-assisted wall-mounted Combi Boilers are required when the installation location is an open space such as a balcony or patio, or when part of the flue route is horizontal (longer than 30 cm). The exhaust fan expels combustion gases outside the building. Therefore, these boilers are typically equipped with a special twin-wall flue with an inner diameter of 6 cm and an outer diameter of 10 cm.
5. A single heating combi boiler may be used for two office units with low domestic hot water demand, provided that the heating capacity matches the total floor area and technical considerations are met. However, installing one heating combi boiler for two residential units is absolutely not recommended, even if the units are small.
6. In systems combining a wall-mounted combi boiler with radiators, ducted split systems, or ceiling fan coils, the hot water must be able to circulate through the coils. Due to the limited head pressure of wall-mounted combi boiler circulation pumps (approximately 6 ft), accurate pipe sizing and installation must be performed based on closed-loop piping standards and under the supervision of HVAC experts.

Selecting the Appropriate Installation Location for Wall-mounted and Floor-standing Combi Boilers

Choosing the appropriate installation location for a wall-mounted or floor-standing heating combi boiler significantly affects its performance and efficiency. Each system meets different requirements based on its model and capacity. For optimal installation, the following points should be considered:

Wall-mounted heating combi boilers are typically suitable for small houses and apartments ranging from 60 to 200 square meters, where space is limited. These systems occupy minimal space and can enhance the aesthetics of the environment. Residential units, offices, shops, and cafés up to 200 square meters commonly use this type of system.

Installing a wall-mounted heating combi boiler can improve the appearance of interior or exterior walls. These systems are often concealed inside kitchen cabinets, keeping them out of sight. However, the top and bottom of the cabinet must be fully open to ensure adequate airflow for proper combustion.

Floor-standing heating combi boilers are more suitable for large houses and villas exceeding 200 square meters that require uniform heating throughout the space. These boilers, installed on the floor, offer higher heating capacity, a hot water storage tank, and a more powerful circulation pump compared to wall-mounted units. Depending on capacity and technical specifications, they can be used for floor areas up to 400 square meters or more.

Performance of Heating Combi Boilers During Different Seasons

During cold seasons, the combi boiler supplies both domestic hot water and heating water for radiators and heating circuits. In summer, its function is limited to domestic hot water supply only. Whenever hot water is required, opening the hot water tap automatically ignites the boiler burner, and once the tap is closed, the burner shuts off. This process is controlled by the electronic control board of the combi boiler.

Purchasing Wall-mounted and Floor-standing Heating Combi Boilers

Today, independent domestic hot water supply for each unit using wall-mounted and floor-standing heating combi boilers is widely welcomed across the world.
As you know, to select and purchase a heating combi boiler, the required capacity and type must first be determined. At the specialized Damatajhiz Group, technical information for dozens of wall-mounted and floor-standing combi boiler models from reputable brands with official warranties is provided to ensure a smart and optimized purchasing experience.

For an approximate calculation of the required heating combi boiler capacity, multiply the apartment area by 150, office areas by 100, and villa or out-of-town building areas by 200 to determine the required gas-fired or diesel-fired wall-mounted or floor-standing combi boiler capacity.

Installation Location of Gas Wall-mounted Combi Boiler

1. The combi boiler must not be installed above a gas stove or any other heat-generating appliances.
2. The minimum distance from the floor to the bottom of the wall-mounted combi boiler must be 120 cm.
3. The minimum distance between the unit and the opposite wall must be at least one meter.
4. The minimum clearance between the boiler and adjacent walls or cabinets on each side must be 15 cm.
5. The vertical distance between the combi boiler flue draft hood and the chimney opening must be at least 50 cm.
6. The wall-mounted combi boiler flue must never be connected directly to the chimney opening inside the wall. Instead, it must be installed at least 30 cm below the chimney opening. It is recommended to install the boiler as low as possible relative to the chimney opening, as increasing this distance improves draft and enhances the discharge of combustion gases. However, if a fan-assisted combi boiler is selected, it can be installed even in locations where part of the flue is installed horizontally.
7. If you intend to purchase a wall-mounted combi boiler and install it inside a cabinet, please note that the boiler requires sufficient oxygen for combustion. Therefore, the bottom or base of the wall cabinet must be open, and the cabinet door should be louvered or slatted to allow adequate air intake from the surrounding environment.

Difference Between Floor-standing and Wall-mounted Combi Boilers

The main differences between floor-standing and wall-mounted combi boilers are as follows:

• Installation location
Floor-standing Combi Boiler: These units are typically installed outdoors and placed on the ground. (However, gas-fired floor-standing combi boilers can also be installed indoors).
Wall-mounted Combi Boiler: These units are installed inside buildings and mounted on walls. They are smaller in size compared to floor-standing models and are suitable for indoor spaces.

• Heating capacity
Floor-standing Combi Boiler: Due to installation in larger spaces, these units offer higher heating capacity, produce a greater volume of hot water, and are equipped with more powerful circulation pumps. Therefore, they are more suitable for buildings with higher heating demand and larger areas.
Wall-mounted Combi Boiler: These units are suitable for residential spaces up to 200 square meters (depending on the boiler heating capacity).

• Hot water storage tank
Floor-standing Combi Boiler: These models are equipped with a coil-type or storage water tank that serves as a hot water reserve. This tank reduces the impact of water outages or pressure fluctuations and increases heating system stability.
Wall-mounted Combi Boiler: Some wall-mounted models also include a water storage tank; however, due to their compact size, the storage capacity is smaller and heating performance may be affected more quickly in case of water interruption.

Therefore, if higher heating capacity and use in larger spaces are required, a floor-standing combi boiler is the more suitable option. However, for smaller spaces with lower heating requirements, a wall-mounted combi boiler may be the better choice. Additionally, water pressure fluctuations and water outages in the area are important factors, where floor-standing combi boilers provide the highest level of stability.

DamaTajhiz; Guide to Selection and Pricing of HVAC and Building Facilities Equipment (Since 2004)

Prepared and organized by: Heating Equipment and Boiler Room Department – Damatajhiz Group

Dear User;

1. We appreciate your trust in the technical opinions of the Damatajhiz Group sales experts. Please note that the final selection of wall-mounted or floor-standing combi boiler brand is ultimately determined by the buyer, based on brand reputation, service quality, and price. However, many users and buyers choose top-selling brands such as Iran Bosch, Butane, Lorch, Ariston, and Iran Radiator combi boilers due to their quality, pricing, and after-sales services.
2. If you have further questions after reviewing the above information to help you decide on purchasing wall-mounted or floor-standing combi boilers, you may contact the specialized Damatajhiz Group at (021-88822550), extensions 107 - 108 - 121 - 122, and receive consultation from the heating equipment and boiler room sales experts.

You can order any HVAC and MEP products, including different types of air washers, cooling towers, air handling units, chillers, industrial evaporative coolers, air curtains, burners, cast-iron or steel boilers, heat exchangers, gas heaters, unit heaters, circulation pumps, sand filters, water and fuel storage tanks, and more, from countries such as the UAE, Armenia, Tajikistan, Georgia, Azerbaijan, Turkey, Oman, Pakistan, Turkmenistan, Afghanistan, Kuwait, Bahrain, Qatar, Iraq, and others across Asia, the Middle East, and Europe, and have them delivered to your city (Manama, Baghdad, Karachi, Dubai, Sharjah, Muscat, Riyadh, Abu Dhabi, Kuwait City, Jeddah, Sana'a, and Doha Amman, Sulaimaniyah, Sofia, Kirkuk, Islamabad, Mosul, Erbil, Dushanbe, Aleppo, Damascus, Baku, Beirut, and Kabul) in the shortest possible time. So, contact us by phone call or WhatsApp message through the number: +98-930-288-0251.

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