Karma BETA 2C vs. BETA 2E – difference between the types and when to choose which
Karma BETA 2C vs. BETA 2E – what's behind the letters and why it matters
When a customer first enters the Karma gas heaters category and starts exploring the model range, the same question almost always comes up: "What is the difference between BETA 2C and BETA 2E? Is it just the price, or is there something more behind it?" The answer is clear – there's much more behind it than just price. These are two technically different construction solutions, each intended for different conditions, a different installation situation, and a different type of user. If you choose the wrong type, you might end up with a device that works, but doesn't work well – or you might hit regulatory limitations that make the installation more expensive and complicated.
In this article we'll go through both types thoroughly: their technical parameters, operating principle, structural differences, installation requirements, typical use, and specific real-life scenarios where one type clearly dominates over the other. If you're looking for a quick comparison of outputs and room sizes, also check out the article What output do I need for a gas heater – calculation based on room area in our Knowledge Center.
What exactly is the Karma BETA gas heater – basic context
The term "gamatka" (German Gamat, derived from "Gas-Mauer-Therme") is a Slovak term for wall-mounted gas air heaters – appliances that draw gas from the network or a cylinder, burn it in a burner, and use the resulting heat to warm the air, which is then distributed into the room. Karma is a Slovak manufacturer with a long tradition, whose products are designed specifically for Slovak and Central European conditions – including the typical quality of gas pipelines, common dimensions of flats and houses, and the regulatory requirements applicable in Slovakia.
The BETA 2 range is the current production line, which replaced older types and brings higher control comfort, better efficiency, and a more modern design. Within this range, there are two basic variants marked by a letter at the end: C and E. These letters are not random – they indicate the method of flue gas discharge and combustion air supply, which is the most important parameter of the whole appliance from a technical and safety point of view.
Technical differences – C-type (conventional flue) versus E-type (sealed combustion chamber)
BETA 2C – open combustion chamber, flue through a chimney
The letter C in the designation BETA 2C means "conventional", or in Slovak terminology, an appliance with an open combustion chamber. What does this mean in practice? The burner and combustion chamber are in direct contact with the air in the room. The appliance draws combustion air directly from the space where it is installed. The flue gases leave through the chimney – either a classic masonry chimney flue or a certified chimney liner.
This principle is simpler, less demanding on the maintenance of the combustion path, and usually cheaper to install – provided the building already has an existing, functional chimney. This is exactly the key condition: a functional chimney with sufficient draught. If the chimney does not work properly – whether due to aging, incorrect sizing, unfavorable weather conditions, or a neighbor building an extension that blocks the prevailing winds – the entire flue gas discharge system fails.
The practical consequence of an open combustion chamber is significant from a safety point of view: if the chimney were to develop negative draught (for example, in strong wind or with a malfunctioning chimney), flue gases including carbon monoxide could start leaking back into the room. That is why the STN EN standard and related regulations require rooms with C-types to have sufficient ventilation – not only technically, but also structurally (permanently open vents, ventilation ducts). A C-type gas heater must not be installed in hermetically sealed spaces (for example, in modern low-energy houses with controlled ventilation and no natural infiltration).
BETA 2E – sealed combustion chamber, double-wall flue
The letter E in the designation BETA 2E refers to "Etage" (floor/apartment), or in modern terminology, an appliance with a sealed (hermetic) combustion chamber, referred to in regulatory language as a type B or C appliance according to the ČSN EN 483/STN EN classification. The combustion chamber is completely separated from the air in the room. Combustion air comes from outside through the outer sleeve of the double-pipe flue (coaxial pipe), and flue gases exit outside through the inner pipe of the same flue.
This means that the appliance draws combustion air from outside, not from the room. The advantages are significant:
- Safety – no risk of flue gases entering the living space in the event of negative draught, because the chamber is hermetically sealed
- Independence from the room's ventilation quality – the appliance works the same way in a tightly sealed modern flat as in an older cottage
- No need for a chimney – the flue is routed directly through the exterior wall or through the roof using coaxial piping
- Higher efficiency – air drawn in from outside is colder in winter, which improves combustion; before the flue gases exit, they preheat the combustion air (counterflow heat exchange in the coaxial flue)
- Usability in flats without a chimney – which today applies to most panel-built flats and modern apartment buildings
The disadvantage of the E-type is the need to route the coaxial flue through the exterior wall or roof. This requires breaking through or drilling an opening with a diameter usually of 100–130 mm, and sometimes also extending the flue if the wall is thicker or if it's necessary to achieve the required distance from a window, corner, or other structural obstacle. For this purpose, accessories such as the Gamat 471 flue extension or the Gamat 473 flue extension, or the VYD60 flue extension are used, depending on specific dimensional requirements. This topic is covered in more detail in the article Gamat flue extension – what diameter and length are suitable for your type.
Comparison of BETA 2C and BETA 2E technical parameters in one table
| Parameter | BETA 2C | BETA 2E |
|---|---|---|
| Combustion chamber type | Open (room air) | Sealed / hermetic |
| Flue gas discharge | Chimney (natural draught) | Coaxial flue through wall/roof |
| Combustion air supply | From the room (infiltration) | From outside via coaxial pipe |
| Need for a chimney | Yes, functional chimney required | No |
| Usability in a flat without a chimney | No | Yes |
| Regulatory ventilation requirements | Strict (permanently ventilated room) | Standard (sealed chamber) |
| Flue installation complexity | Lower (with existing chimney) | Higher (drilling wall, coaxial piping) |
| Typical use | Older houses, cottages, boiler rooms with a chimney | Panel-built flats, new buildings without a chimney |
| Safety in case of chimney draught failure | Risk of flue gas backflow | None (chamber isolated) |
Specific models – what you'll find in our offer
In the current offer at Atria.sk, you'll find specific output variants for both types. For the C-type, these are for example Karma BETA 2C 01 and Karma BETA 2C 02 – both intended for connection to a chimney flue, differing in their output level and therefore in the suitable room area. Output is a key parameter in the selection process – if you're wondering how to correctly size the input for the room area, we recommend reading the article What output do I need for a gas heater – calculation based on room area, where you'll find a specific calculation method with sample values.
The same selection principle applies to the E-type (sealed chamber) – the output must match the heat loss of the space, only the installation and structural requirements differ. For both types, undersizing is a mistake, but oversizing is also unsuitable – the gas heater would only operate in short cycles and would wear out faster.
When to choose BETA 2C – practical scenarios from typical orders
Scenario 1: A holiday cottage with a working chimney
This is the classic case. The customer has a wooden or brick cottage from the 1970s, with a brick chimney flue of 150–180 mm diameter. The cottage's heat losses are higher (older insulation, wooden windows), requiring output somewhere between 4 and 7 kW. The property is used irregularly, mostly on weekends. The chimney is functional and inspected by a chimney sweep every 2 years. In this case, BETA 2C is the optimal choice: simple installation by connecting to the existing chimney flue, lower purchase price, trouble-free operation with open ventilation of the cottage (older-type windows do not provide hermetic sealing).
Scenario 2: A family house from the 1990s, replacing an old appliance
The customer is replacing an old gas heater that was breaking down or reaching the end of its service life. The house has a chimney, and the old appliance was also a C-type. If the chimney is in good condition (verified by inspection), the choice is clear – BETA 2C is a direct replacement, with the same connection requirements and no structural modifications. The advantage is that there's no need to deal with a new wall opening, no coaxial piping, and no extensions.
Scenario 3: Garage or workshop extension
Here you need to be careful. A garage is a room with a high risk of air contamination (exhaust fumes, chemical vapors), which is why the C-type with an open chamber is directly prohibited in garages in several countries. In Slovakia, installing a C-type in garages is very problematic in terms of applicable STN standards and inspectors' decisions. In this case, the E-type is clearly recommended.
When to choose BETA 2E – practical scenarios from typical orders
Scenario 1: A panel-built flat or apartment building without a chimney
The most common case for the E-type. The customer lives in a panel-built building where there has never been an individual gas appliance with a chimney – only central heating. Now they've decided to switch to individual gas heating (either due to a change of heat supplier or for reliability reasons). No chimney is available. The only option is the E-type with a coaxial flue through the exterior wall. Installation requires the building manager's consent and, in some cases, a building permit or a minor construction notification – this must be checked in advance at the local building authority.
Scenario 2: A new building with triple-glazed windows and vapor insulation
Modern low-energy houses are almost hermetically sealed. Air infiltration through windows and doors is minimal – this is intentional, to reduce heat losses. If you installed a C-type in such a house, combustion air would quickly run short, the burner would have combustion problems, and additionally negative pressure would build up in the room, potentially causing the chimney to "reverse" – with flue gases flowing back in. The solution is exclusively the E-type, because it draws air from outside, independent of the interior's degree of airtightness.
Scenario 3: Bathroom renovation or heating a room without a window
Although gas heaters are not primarily designed for bathrooms (gas water heaters are more commonly used there), sometimes there's a need for heating in a space without direct ventilation. The E-type is safer because it doesn't need air for combustion from that space – so it doesn't create negative pressure or contaminate the air with combustion by-products.
Installation and structural requirements – where the types differ in practice
From an installation point of view, BETA 2C is simpler if a chimney already exists. All that's needed is a connection using a flexible stainless steel or aluminum hose to the chimney flue, or a rigid pipe. The standard connection diameter is 100 mm for most medium-output models. The chimney must have a valid inspection – this is not just a formality, it's a requirement of insurance companies and gas suppliers alike. If there's no inspection, the installation is not legal, and in the event of an insurance claim, you may face a refusal of coverage.
For BETA 2E, the situation is different: you need an opening in the exterior wall, coaxial piping, and installation of an outer grille. The standard coaxial diameter is 60/100 mm or 80/125 mm (inner/outer pipe). The flue length depends on the wall thickness – for standard panel-building walls (250–350 mm), the basic length is sufficient, while for thicker walls or when the flue needs to be set back from the façade, extensions are used, such as the VYD60 flue extension. The flue must terminate at least 300 mm from any opening in the building (window, door, ventilation shaft) to prevent recirculation of flue gases – this is one of the parameters the inspector physically measures.
The entire installation procedure – from mounting the appliance to first start-up – is described in the article Installing a Karma gas heater step by step – procedure and requirements. If you're deciding between mechanical vs. electronic thermostat control, that topic is covered in a separate article, Mechanical vs. electronic control of the Karma gas heater – which is better.
Efficiency, operating costs, and energy consumption
In terms of the calorific value of the gas, the C-type and E-type are comparable at the same burner output – both burn gas with the same efficiency, since the difference doesn't lie in the combustion process itself, but in where the combustion air comes from and where the flue gases go. In practice, the E-type has slightly higher efficiency in winter, because the coaxial flue works as a counterflow heat exchanger: cold outside air drawn in to the burner is preheated by the outgoing flue gases. This effect is measurable, but not dramatic – in practice, we're talking about a few percentage points, not tens of percent.
A more significant influence on operating consumption comes from correctly setting the thermostat and using regulation. This topic is covered in the article How to correctly set up and operate a Karma gas heater to save energy.
As for purchase price, the C-type is usually cheaper both to buy and to install (if a chimney exists). The E-type requires coaxial accessories and drilling through the wall – this can add several dozen to several hundred euros to the total installation cost, depending on wall thickness, scaffolding height, and other factors. On the other hand, if the chimney doesn't exist or would require extensive repair and recertification, the E-type may ultimately be the cheaper solution overall.
Standards, regulations, and safety aspects – what to know before choosing
The installation of gas appliances in Slovakia is subject to several regulations. The key ones are the STN EN standards for gas appliances (specifically STN EN 613 for unregulated convection gas heaters and STN EN 483 for boilers), as well as Decree No. 508/2009 Z.z. and related occupational health and safety regulations. From a practical standpoint, the most important thing for the customer is the following:
- A gas heater may only be installed by a person with valid authorization for the installation and repair of gas appliances (a trade license with the corresponding scope, or a certificate from SPP or an equivalent authority)
- After installation, a report on the professional inspection and test must be issued
- The C-type requires a chimney inspection before connection (and subsequently on a regular basis according to regulations – usually every 2 years for appliances with an output up to 50 kW)
- The E-type requires the flue to meet minimum distances from building openings according to the manufacturer's standard and national regulations
- A room with a C-type must have permanently accessible ventilation – a window, ventilation ducts, or grilles with a defined cross-section (usually a minimum of 150 cm² for appliances up to 7 kW)
The consequences of not meeting these requirements are not just theoretical. In our order-fulfilment practice, we encounter cases where old gas heaters were installed "unofficially," and this caused serious problems when selling the property or in the event of an insurance claim. If you've bought a flat or house with an old gas heater and don't know anything about its history, we recommend having an inspection carried out as soon as possible.
Combining with additional accessories and extras
Besides the appliance itself, it's good to think about accessories in advance. For the C-type, chimney adapters and seals for connecting to the flue are essential. For the E-type, coaxial flues and their extensions are essential. If the wall through which the flue passes is thicker than the standard telescopic length of the basic flue, extension pieces are needed. In the Atria offer, you'll find for example the Gamat 471 flue extension and the Gamat 473 flue extension – these components are compatible with the respective models and guarantee correct installation without the need to improvise on site.
Besides the flue, it's also good to consider thermostatic control. Both types (C and E) are available with a mechanical or electronic thermostat. Electronic thermostats allow programmable time zones, night setbacks, and more precise temperature control, which significantly affects gas savings in real operation. A comparison of both types of control can be found in the article Mechanical vs. electronic control of the Karma gas heater – which is better.
Typical selection mistakes and how to avoid them
Over years of experience with orders, the same mistakes in choosing the type of gas heater keep occurring. Here's an overview of the most common ones:
- Choosing a C-type for a space without adequate ventilation – e.g., a modern house with plastic windows and no ventilation grille. Result: incomplete combustion, increased CO production, potential risk of poisoning.
- Underestimating the condition of the chimney – the customer knows a chimney exists but doesn't check whether it's blocked, cracked, or unsuitable for the new appliance (different diameter, different height). A chimney inspection before installation is a necessity, not an unnecessary expense.
- Choosing an E-type without verifying the possibility of a flue through the wall – in some apartment buildings, managers do not allow breaking through the exterior wall, or the wall is protected (e.g., a historic building). This must be checked before purchasing the appliance.
- Ignoring output – buying "whatever we liked" without calculating heat losses. A gas heater with an output of 3.5 kW will not heat a 35 m² room with old windows in winter.
- Attempting DIY installation – gas appliances cannot be legally installed without the appropriate authorization. In such a case, the insurance policy is invalid in the event of fire or explosion.
Frequently Asked Questions (FAQ)
Can I replace an old C-type gas heater with a new E-type?
Yes, but it's not an automatic swap. If you're replacing a C-type with an E-type, you must seal off the chimney flue and set up a new coaxial flue through the exterior wall. This requires a structural modification and a new assessment by an inspector. On the other hand, the advantage is that after installing the E-type, you're free from dependence on the chimney and its maintenance.
Can I connect an E-type to an existing chimney flue?
No. The E-type (sealed chamber) is structurally designed exclusively for a coaxial flue through a wall or roof. Connecting to a chimney would mean the outer sleeve of the coaxial pipe (combustion air supply) would have nowhere to draw fresh outside air from. In addition, this would be in violation of the manufacturer's standard, and the installation would not be legal.
What is the difference between BETA 2C 01 and BETA 2C 02?
These are output variants within the same construction family of the C-type. The numbers 01 and 02 indicate a lower and higher output (or a different output level). Karma BETA 2C 01 is suitable for smaller spaces, while Karma BETA 2C 02 covers larger rooms with higher heat loss. Specific output values and recommended areas can be found in the technical sheets of the individual products.
Is the E-type safer than the C-type?
In terms of the risk of flue gases leaking into the living space, yes – the sealed combustion chamber of the E-type physically prevents flue gases from entering the interior in case of draught failure. The C-type is safe with correct installation and proper ventilation, but it involves a greater number of variables (chimney condition, room ventilation) that can degrade over the years. That's why experts have preferred the E-type over the last decade wherever technically possible.
Can I use a gas heater as the only source of heat for the entire flat?
A gas heater is primarily designed to heat one or two connected rooms. Heating an entire multi-room flat would require several appliances or a special solution with warm air distribution – this is technically possible, but requires a design and calculation. We generally do not recommend using a gas heater as the sole heat source for an entire 3-room flat without prior consultation with a designer.
How long does the installation of a gas heater including the flue take?
For the C-type (connection to an existing chimney in good condition), expect 2–4 hours of work by an experienced installer. For the E-type with wall drilling and coaxial installation, the usual time is 4–6 hours, or more for more complicated flue routing (extensions, corner adapters). You should also add the time needed to wait for the inspector's assessment and the subsequent commissioning and testing of the appliance to the total time.
Conclusion – so how do you decide?
Choosing between BETA 2C and BETA 2E is not just a matter of price or fashion trends. It's a technical decision that depends on the specific conditions of your property. If you have a functional, inspection-verified chimney and a room with sufficient ventilation – the C-type is a logical, proven, and economical choice. If you don't have a chimney, the space is hermetically sealed, or you're installing in a panel-built flat – the E-type is the only correct way to go.
In cases where a chimney exists but its condition is questionable or requires costly repair, the E-type may ultimately be more economical as well. We always recommend consulting with an installer before making a final decision – they will physically inspect the space and assess the actual conditions – what a customer describes over the phone and what an installer sees on site sometimes differ significantly.
For further information on selection, installation, and operation, see the other articles in our Knowledge Center: How to choose the right Karma gas heater for your space, Installing a Karma gas heater step by step, or Common Karma gas heater faults and how to fix them. If you're interested in specific questions, answers to the most frequent ones are summarized in the Frequently Asked Questions about the Karma gas heater section.
Do you have a question on this topic?
Can't decide, or are you dealing with a specific situation in your household? Write to us – we're happy to help.