Common Karma boiler faults and how to fix them

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Common Faults of Karma Infrared Heaters and How to Fix Them

Karma infrared heaters are reliable and widely used ceiling-mounted infrared heaters found in garages, workshops, warehouses, fitness centers, as well as recreational areas and terraces. Despite their high structural reliability, operational problems can appear over time in these devices as well – either due to improper installation, neglected maintenance, or normal component wear. This article was created based on experience from real orders and service calls. Here you will find a description of the most common faults, their causes, diagnostics, and specific steps for resolving them – including those you can handle yourself without calling a service technician.

Before you start any diagnostics or repair, keep one fundamental principle in mind: the Karma heater is a gas appliance with an open burner and electric ignition. Any work on gas components (nozzle holder, control valve, gas supply) must be performed exclusively by an authorized service technician with the appropriate certification. Under certain conditions, you can handle the electrical part and cleaning yourself – but always after disconnecting the device from the power supply and closing the gas valve.

How the Karma Heater Works – A Brief Technical Overview

To understand the faults, you need to know the operating principle. The Karma heater is a gas infrared radiant heater with a short or medium wavelength range. Gas (natural gas or propane-butane) flows through a control valve into the burner, where it is ignited by an electric ignition (spark igniter). Combustion takes place on a ceramic or stainless steel grid plate – the emitter, which glows red and radiates infrared radiation directly into the space. Flue gases are discharged through a flue pipe – either directly through the wall or using a flue extension leading outside the building.

The electrical part includes: a thermostat (mechanical or electronic), a control unit (controller), an ignition transformer, an ionization electrode (flame monitoring), and possibly a remote control. The gas is controlled by: a solenoid valve and a pressure regulator. The mechanical part consists of: a reflector, an emitter, the burner body, and the flue pipe.

Diagram of the functional blocks of the Karma heater – from gas supply through the burner to the flue outlet and control

The Heater Won't Ignite – The Most Common and Varied Fault

This is by far the most common reason customers call for service or search for help online. "The heater won't ignite" can mean dozens of different causes, which is why it's important to proceed systematically, starting with the simplest.

Step 1: Check the Gas and Electrical Supply

This may sound too obvious to mention, but experience shows that dozens of service calls turned out to be simply because the customer forgot to open the gas shut-off valve, or a circuit breaker had tripped. Always start here:

Is the ball valve on the gas supply to the heater open?
Is the propane tank empty (in the case of a propane-butane connection)?
Is a circuit breaker tripped or an RCD (residual current device) activated on the distribution board?
Is the heater's power cable physically connected and undamaged?
If the heater is controlled by a thermostat – is the thermostat set to a temperature higher than the current room temperature?

Step 2: Identify Where the Process Stops

Modern Karma heaters have a standard ignition cycle: once the thermostat calls for heat, the control unit opens the solenoid valve, activates the igniter (you'll hear "clicking"), and after a few seconds gas should flow through the burner and be ignited by the igniter. The ionization electrode confirms the presence of a flame, and the control unit stops clicking – the burner burns steadily. If any step fails to occur:

Nothing happens, no clicking: the problem is in the power supply, the thermostat, or the control unit.
Clicking occurs, but no flame forms (the heater goes into a fault state / safety shutdown): the problem is likely in the gas supply, the solenoid valve, the ignition electrode, or the ionization electrode.
A flame briefly forms but goes out immediately: the ionization electrode fails to confirm the flame – either it is dirty, misaligned, or there is a problem with the control unit.

In terms of what you can handle yourself: you can check the electrical part (power supply, thermostat, wiring) after disconnecting from the mains. Cleaning the ionization and ignition electrodes is also usually a task available to a handy owner. The solenoid valve and gas piping – always leave to a technician.

Dirty Ionization Electrode – The Silent Culprit

After years of operation, combustion products – oxides, soot, fine deposits – build up on the ionization electrode. The electrode stops reliably detecting the presence of the flame, and the control unit interprets the situation as "flame not burning" – the valve closes and the heater enters a safety fault mode (usually a flashing LED or an error code on the display). Solution: gently sand the tip of the electrode (contact point) with fine sandpaper (grit 400), or carefully wipe it with acetone, check the gap from the burner plate (typically 3–5 mm depending on the model), and tighten the mounting screw.

Position of the ignition and ionization electrodes relative to the burner plate – the correct gap is key for reliable ignition

The Heater Burns, but Heat Distribution Is Uneven or Output Is Low

This is the second most common category of complaints. Customers say: "The heater burns, it glows, but the room is still cold" or "One part of the space is warm, the other is freezing." There are several causes:

Dirty or Damaged Reflector

The heater's reflector (the shiny parabolic panel above the burner) directs infrared radiation down and forward. If the reflector is covered with dust, greasy vapors (typical in kitchens or car repair shops), or is mechanically deformed, the radiation pattern changes. The result is a "hot spot" directly under the heater, while the surrounding area remains insufficiently heated. Solution: clean the reflector with a soft cloth dampened with soapy water or a special stainless steel surface cleaner (caution – do not use abrasive agents, as they could damage the reflective coating). If the reflector is deformed, it needs to be replaced.

Partially Clogged or Damaged Emitter

The ceramic or stainless steel emitter (burner plate) can crack, break, or have clogged pores (in the case of ceramic). In practice, this means part of the emitter does not heat to the same temperature – some areas are bright (burning), others dark (non-functional). Result: uneven output, lower overall performance, but also an increased risk of incomplete combustion and gas leakage into the room. Solution: visually inspect the emitter after switching on (viewed from below, at a safe distance). If visible damage is found – replace the emitter. This task is possible for a handy owner in the case of the ceramic type, after disconnecting the gas and electricity, but caution is required.

Incorrect Installation Heights and Angles

Karma heaters are not designed to be installed at any height equally. A heater mounted too low "scorches" only a narrow strip of floor directly beneath it, while one mounted too high loses effectiveness. Typical recommended heights are 2.5–6 m depending on output. The tilt angle of the burner also affects the spread – many models can be tilted 15–30° from vertical. If you feel that the heater is not heating evenly, check the documentation for your model regarding the recommended installation height and angle. This topic is covered in more detail in the article Installing the Karma Heater Step by Step – Procedure and Requirements in our Knowledge Center.

The Heater Produces an Irregular or Unpleasant Smell

A smell coming from the heater is always a serious signal that requires an immediate response. There are various types of smell, each with a different cause:

Smell on First Startup (New Heater or After Long Idle Period)

When starting a new heater for the first time, or after a longer seasonal break, a slight smell may be noticeable – this is the burning off of dust, protective coatings, and manufacturing residues on the emitter and reflector. This smell disappears within 15–30 minutes of operation and is harmless. We recommend performing the first start-up with windows open for ventilation.

Persistent Smell of Combustion Products (Sooty Smell)

If the heater continues to smell of combustion or combustion products even after it has warmed up, the causes are:

Incorrect gas-to-air ratio – a mixture that is too rich (insufficient air) causes incomplete combustion and the formation of CO. This is a serious safety situation – switch off the device immediately and call a service technician.
Blocked flue outlet – if the flue pipe is not freely open, exhaust gases cannot escape and partially flow back into the room. Visually check the flue pipe passage, or use the correct workshop component – e.g. Gamat 471 Flue Extension or Gamat 473 Flue Extension – and make sure the outdoor flue outlet is not covered by a snowdrift, a bird's nest, or mechanical damage.
Greasy deposits on the reflector or emitter – in industrial operations, oily vapors can accumulate on the heater's surfaces, which produce a smell under thermal load. Solution: regular cleaning (at least once per season).

Smell of Gas – Immediate Action Required

If you smell raw gas (the characteristic hydrogen sulfide odor added to natural gas for leak detection), immediately:

Do not switch any electrical appliances on or off (a spark could cause an explosion)
Close the gas supply ball valve
Open windows and doors for ventilation
Leave the area and call the gas emergency line or the fire department
Do not return to the area until it has been checked by a professional

Flue and Exhaust Faults

The flue pipe is one of the most frequently underestimated parts of the installation. Experience shows that flue errors are behind many mysterious faults – from unexplained shutdowns to error codes and odors.

Flue Pipe Too Long or Incorrectly Sized

Each heater model has precisely specified maximum flue pipe lengths and diameters. If the pipe is too long, the pressure resistance is too high and the exhaust gases cannot be properly discharged – the result: the heater repeatedly ignites and goes out, or a backflow flap switch (if installed) is activated. If the pipe diameter is too small, the same effect occurs. Always use components sized for your specific model – for example, the VYD60 Flue Extension is intended for a specific diameter, and combining incorrect diameters leads to problems. This topic is covered in detail in the article Gamat Flue Extension – Which Diameter and Length Are Suitable for Your Model.

Condensate in the Flue Pipe

In cold weather and with short cycles (the heater runs briefly and then switches off), condensate – water from the exhaust gases – can form in the flue pipe. If the pipe is installed sloping toward the heater (it should correctly slope away from the heater, i.e. rising toward the outlet), condensate flows back into the heater body, which can cause corrosion and faults. Check the pipe's slope – the minimum slope away from the heater toward the outside should be 1–2% (at least 1 cm per running meter of length).

Mechanical Damage or Leaking Joints

A vibrating or worn clamp on the flue pipe joint can cause the joints to leak. Exhaust gases then escape into the room instead of being discharged outside. Symptoms: odors during operation, black deposits around pipe joints. Visually inspect all joints; if in doubt, hold your hand or a moist finger near them (moisture will reveal air movement at the joints).

Correct (rising) vs. incorrect (falling) flue pipe routing – with an incorrect slope, condensate flows back into the heater

Thermostat and Control – Faults That Aren't Actually a Fault of the Heater

An interesting phenomenon we regularly encounter in service: the customer claims the heater is broken, but in fact it's the thermostat or control panel that's faulty. Since the thermostat and the heater are two separate devices, thermostat faults manifest themselves as heater faults.

Mechanical Thermostat – Most Common Problems

Bimetallic mechanical thermostats are simple and cheap, but have several weak points:

Calibration drift: After years of operation, the bimetallic element may lose its precise calibration – a thermostat set to 18°C may not switch on until 22°C, or vice versa. Verify this with a room thermometer and compare it with the setting. Some mechanical thermostats can be recalibrated (a small adjustment screw under a cap), others need to be replaced.
Oxidized contacts: If the heater stops responding to the thermostat or behaves erratically (sometimes it responds, sometimes it doesn't), the thermostat's contacts may be oxidized. Solution: replace the thermostat.
Incorrect thermostat placement: A thermostat placed near a window, by an entrance door, in the heater's exhaust airflow, or conversely too close to a heat source (stove, computer) measures an unrepresentative temperature and switches the heater on/off incorrectly.

Electronic Controller – Diagnostics

Modern Karma BETA 2C heaters, such as the Karma BETA 2C 01 or Karma BETA 2C 02, may be equipped with an electronic controller with a digital display. Electronic controllers are more precise but have their own error codes and behaviors:

Display flashes or shows an "E" code: each code has a specific meaning – e.g. E1 may indicate an ignition fault, E3 a temperature sensor fault. Always check the manual for your specific controller model.
The heater won't turn on after a restart: Some electronic controllers have a protective delay after a fault shutdown – waiting 3–5 minutes before the next ignition attempt. Simply wait.
Lost settings after a power outage: Some older controllers do not have backup memory. After an outage, the program must be reset. Solution: use a controller with battery backup, or note down your settings.

A more detailed comparison of mechanical and electronic control is covered in the article Mechanical vs. Electronic Control of the Karma Heater – Which Is Better in our Knowledge Center.

Unusual Sounds During Operation

Karma heaters are not devices that should produce loud noises. Slight crackling during start-up (thermal expansion of metal parts) is normal. If other sounds appear, it's a warning sign:

Hissing or Crackling of the Burner

Intermittent crackling, hissing, or "sputtering" of the flame may indicate an unstable gas supply (pressure fluctuations), a partially clogged nozzle, or a dirty emitter. For natural gas, check whether the network pressure is dropping (due to other appliances) – during pressure fluctuations, the heater may burn incorrectly. For propane, check whether the tank is nearly empty.

Resonant Humming

Low-frequency humming or buzzing can come from:

Vibration of a loose reflector or cover – check all mounting screws
Flue pipe resonance – if the pipe is not sufficiently secured and vibrates with the flow of exhaust gases, it can produce a humming sound. Add clamps to secure the pipe.
Solenoid valve – for some valves, a slight buzzing is normal, but intense buzzing may indicate a worn valve diaphragm.

Knocking or Metallic Cracking During Heating and Cooling

This is usually a normal phenomenon – it is the thermal expansion of the metal sheets of the reflector and heater body. If it is too intense or occurs at incorrect moments (not just during start-up/shutdown), check the mounting of the expansion elements according to the installation instructions.

Visual Anomalies of the Burner – Flame Color and Emitter Appearance

Correct flame color (blue to blue-orange) vs. incorrect (yellow, with sooty patches) – visual inspection of the burner is the basis of diagnostics

The color of the burner plate and flame is a good diagnostic tool:

Ceramic emitter – even red glow: normal condition
Dark spots on the emitter: clogged pores or cracks – reduced output, uneven combustion
Blue flame with orange edges: correct combustion of natural gas
Yellow or orange flame without a blue core: mixture too rich (insufficient air), incomplete combustion, formation of CO – switch off immediately, call a technician
Black soot on the reflector or around the heater: long-term incomplete combustion – a serious safety situation

Error Codes and Safety Lockouts

Modern heater control units store fault states and signal them via an LED indicator or a display code. Most models have the following types of safety lockout states:

Ignition fault (Lock-out): After several failed ignition attempts (typically 2–3 attempts), the heater locks out and waits for a manual reset. The reset is usually performed by holding down the reset button (5–10 seconds) or by disconnecting and reconnecting the power supply. Causes: no gas, faulty ignition electrode, faulty ionization electrode.
Thermal cut-out: If the temperature inside the heater exceeds the safety limit (e.g. due to a blocked flue or insufficient minimum distance from combustible materials), the thermal cut-out activates. Some are automatic (they reset once cooled), others are manual (a reset button on the heater body must be pressed).
Temperature sensor fault: On electronically controlled models, there may be a problem with the NTC temperature sensor – either a broken wire or a faulty sensor. Result: the heater fails to start, or starts and immediately switches off.

Always identify and eliminate the cause first after a safety lockout – only then perform a reset. Repeating the reset without eliminating the cause leads to further lockout states and can shorten the lifespan of the control unit.

Fault Prevention – A Practical Service Plan

Prevention is cheaper than repair. Based on experience, we recommend the following annual maintenance cycle, which significantly reduces the occurrence of faults:

Before the Season (September/October)

Visual inspection of the reflector, emitter, and heater body – cracks, corrosion, mechanical damage
Cleaning the reflector with a soft cloth
Checking and cleaning the ignition and ionization electrodes
Checking and cleaning the flue pipe – passage, tightness, slope
Checking the mounting brackets and all pipe joints
First test start-up – monitoring flame color, odors, sounds
Checking the thermostat's settings and function

During the Season (Every 4–6 Weeks)

Visual inspection of the burner during operation (color of the emitter's glow)
Checking that the outdoor flue outlet is not blocked (snow, ice)
Checking the tightness of gas connections with soapy water (once per season)

After the Season (April/May)

Thorough cleaning of the entire device
Closing the gas shut-off valve during the off-season idle period
Noting any unusual behavior during the season for a service technician to check

You can find a more detailed guide to DIY and service maintenance in the article Maintenance and Servicing of the Karma Heater – What You Can Do Yourself and When to Call a Technician in our Knowledge Center.

When to Call a Service Technician – Clear Boundaries

Establishing the boundary between what is DIY and what requires a professional is important not only for safety reasons, but also from the point of view of warranty and legal liability. Here is a clear list:

You can handle this yourself (after disconnecting from the power supply and closing the gas valve):

Cleaning the reflector and the outer surface of the body
Cleaning the ionization and ignition electrodes (without changing their position or adjustment)
Replacing the thermostat (with power disconnected)
Cleaning and visually inspecting the flue pipe
Tightening loose mechanical joints (mounting elements, cladding)
Resetting the device according to the manual (after identifying and eliminating the cause)
Checking and replacing fuses in the electrical connection

This always requires a certified service technician:

Any work on the gas piping system (nozzle, control valve, solenoid valve, gas connections)
Replacing the control unit
Setting the air/gas ratio (flue gas analysis)
Replacing the emitter when it involves access to gas components
Checking the tightness of the gas piping system (gas meter tests)
Any intervention after detecting the smell of gas
The first commissioning after installation

Frequently Asked Questions (FAQ)

The Karma heater is trying to ignite (clicking), but no flame forms. What should I do first?

The first step is to check the gas supply – whether the valve is open and whether there is enough gas in the tank (for propane). If gas is flowing, the next step is to check the ignition electrode – whether it is dirty, cracked, or misaligned. If the electrode is fine and the heater still won't ignite, the problem could be in the solenoid valve (not letting gas through) or in the control unit – it's time to call a technician. Remember that after several failed attempts, the heater may enter lock-out mode and require a manual reset.

The heater ignites, but goes out after a few seconds. Why?

The most common cause is a dirty or misaligned ionization electrode. The electrode fails to detect the flame, and the control unit safely closes the solenoid valve. Clean the tip of the ionization electrode with fine sandpaper (grit 400), check the correct distance from the burner plate (3–5 mm), and tighten the mounting screw. If the problem persists even after cleaning, it may be a problem with the control unit or the ionization wire – call a service technician.

I smell an unpleasant odor from the heater, but it's not a gas smell. What could it be?

After a longer break or in a dusty environment, the usual cause of the smell is burnt dust and grease on the reflector and emitter. This disappears after 15–30 minutes of operation with good ventilation. If the smell persists for a long time and resembles combustion or soot, check whether the flue pipe is unobstructed – a blocked flue causes exhaust gases to flow back into the room. If you notice any smell you cannot identify, it's better to switch off the heater and call a technician.

Can I replace the flue extension on the heater myself?

Yes, replacing the flue extension is accessible to a handy owner in most cases – it is a mechanical connection without any work on gas or electrical components. It is important to use the correctly sized part for your model (the diameter and maximum length are stated in the documentation). For example, the Gamat 471 Flue Extension and the Gamat 473 Flue Extension are intended for different diameters – it depends on the specific heater model. After replacement, always check the tightness of the joints and the correct slope of the pipe (rising outward by at least 1%).

My heater is an older model and I don't have the manual. Where can I find error codes and settings?

Documentation for older Karma models can be obtained directly from the manufacturer (Karma s.r.o.) or from an authorized dealer. When purchasing spare parts via atria.sk, you can ask for technical documentation. For general information about the model and settings, also check the articles How to Properly Set Up and Operate the Karma Heater for Energy Savings and Frequently Asked Questions About the Karma Heater in our Knowledge Center.

My Karma heater works, but I feel it consumes too much gas. Is this a fault?

Not necessarily – increased gas consumption can have several causes that are not a classic fault: improper thermostat placement (measuring an unrepresentative temperature and causing the heater to run too long), heater output too high for the given space (the heater is oversized), insufficient thermal insulation of the space, or incorrect temperature program settings. Before calling a technician, read the articles What Heater Output Do I Need – Calculation Based on Room Area and How to Properly Set Up and Operate the Karma Heater for Energy Savings – you will very likely find the answer without needing a service call.

Conclusion – A Preventive Approach Saves Time and Money

Karma heaters are structurally robust devices that, with proper installation and regular maintenance, can operate reliably for decades. Most of the faults we encounter in practice are directly related either to neglected maintenance (dirty electrodes, blocked flue, dirty emitter) or to installation errors (incorrectly sized flue, wrong pipe slope, improper mounting height). A minority of cases represent actual component wear – of the ionization electrode, control unit, or emitter.

Key conclusion: gas appliances always demand respect. You can handle the electrical part and cleaning yourself under certain conditions, but any work on gas components should always be left to a certified service technician. Safety is not an area where it pays to cut corners. To choose the right heater for your space needs, check out our article How to Choose the Right Karma Heater for Your Space, and for a comparison of specific models

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