Installation of the Buderus Logamax Electric Boiler – Procedure and Requirements

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Installing the Buderus Logamax Electric Boiler – Complete Procedure and Technical Requirements

The Buderus Logamax E213 electric boiler is a device that, compared to gas or solid-fuel boilers, requires considerably less construction work – but the electrical part of the installation deserves even greater attention. Installing this boiler is not rocket science, but every detail counts: correct cable dimensioning, correct circuit protection, correct hydraulic connection, and correct placement of the unit all determine whether the boiler will operate reliably for decades, or cause unnecessary failures, excessive costs, and, in the worst case, a safety incident. This article covers the entire process from start to finish – from the first measurement on the wall to the first start-up and handover to the customer.

If you are still wondering what output you need, first read the articles What Output of the Buderus Logamax Electric Boiler Do I Need for My House and How to Choose a Buderus Logamax Electric Boiler – What to Focus On. Installation is much easier when you are confident you have chosen the right model.

Overview of Models and Their Basic Technical Parameters Relevant to Installation

The Logamax E213 series includes five output variants. Each has slightly different electrical requirements, which directly affect the dimensioning of the connection and circuit protection. Before ordering materials, it is essential to know the specific values for your particular model.

Model	Input power [kW]	Rated current [A] (400 V)	Recommended fuse/breaker	Min. cable cross-section (Cu)
Logamax E213-4	4 kW	~5.8 A	3× 10 A / 16 A (B)	3× 1.5 mm²
Logamax E213-6	6 kW	~8.7 A	3× 16 A (B)	3× 2.5 mm²
Logamax E213-8	8 kW	~11.5 A	3× 16 A (B) or C	3× 2.5 mm²
Logamax E213-10	10 kW	~14.4 A	3× 20 A (B/C)	3× 4 mm²
Logamax E213-14	14 kW	~20.2 A	3× 25 A (B/C)	3× 6 mm²

Note: The values shown are based on typical operation at 3×400 V/50 Hz. The actual choice of cable cross-section depends on the length of the run, the installation method, and current standards. Always consult an electrical designer.

Conditions and Prerequisites Before Installation

Construction and Space Requirements

The Logamax E213 is designed for wall mounting. Unlike floor-standing boilers, it does not require a boiler room with a ventilation opening or a flue gas duct – this is one of the main practical advantages. Nevertheless, several rules apply:

Wall load-bearing capacity: Depending on the model, the boiler weighs 18–26 kg. Most masonry, exposed concrete, and plasterboard partition walls with a metal frame can easily bear this load. Never hang anything on plasterboard without a metal support.
Minimum clearances: Buderus recommends at least 100 mm above the boiler (for service access to the expansion tank and air vent), 50 mm on the sides, and at least 400 mm in front of the boiler. Most service work is done from the front, so never place a cabinet directly in front of the unit.
Permissible environment: The boiler is designed for indoor spaces with a temperature of 0–45 °C and relative humidity up to 70%. A damp basement, an uncovered terrace, or an unheated garage are not suitable locations.
Access to the electrical distribution board: The cable should be routed directly from the distribution board – not extended with extension cables, and not through a socket. This is a fixed installation.

Electrical Preparation and Connection Requirements

This is the most frequently underestimated point. Customers buy the boiler and then find out that their electrical connection lacks sufficient capacity. The grid connection and the main circuit breaker must correspond to the total installed appliance load of the house. For example, if your house has a main circuit breaker of 3×25 A and you add an E213-14 boiler (20 A), you may not have enough reserve for other appliances at peak load. This is covered in a separate article, Power Supply and Electrical Requirements of Buderus Logamax Boilers – What You Need to Know.

Practical procedure before installation: call an electrician, have the total installed power calculated, or ask the distributor to increase the main circuit breaker. This process can take 4–8 weeks, so address it in advance, not just before the boiler installation.

Required Tools and Materials

An experienced installer prepares everything before arriving at the job. Experience shows that a forgotten reducing fitting or a missing sealant means a trip to the warehouse and a lost working day.

Hammer drill, drill bits for concrete/brick (typically Ø 10 mm for the relevant anchors)
Spirit level (min. 60 cm) – the boiler must hang level, otherwise it will not vent properly
Torque wrench (recommended torque 30–40 Nm for hydraulic connections)
Thread sealing paste or PTFE tape for threaded joints
Multimeter for checking voltage and phase sequence
Screwdriver for terminal block connections (insulated, 1000 V category)
Cable clips, electrical tape, heat-shrink tubing
Reducers and elbows according to the hydraulic design (usually G¾" or G1" threads)
Expansion tank (if the boiler's built-in capacity is insufficient for the system volume)
Pressure gauge and filling valve with a check valve
Automatic air vent – if not already present elsewhere in the system

Step by Step: The Installation Itself

Step 1 – Unpacking and Checking the Delivery

Before anything else, unpack the boiler and check the contents against the delivery note. The E213 series typically includes: the boiler itself, a mounting bracket (or screws directly), possibly a mounting template, hydraulic and electrical wiring diagrams, a warranty card, and an operating manual. If anything is missing or the boiler has been damaged in transit, file a claim immediately – not three days after installation. Also check the pre-charge pressure of the expansion tank (if included with the boiler), which is typically 0.75–1.0 bar.

Step 2 – Marking the Position and Installing the Mounting Bracket

Using the mounting template or the dimensions given in the manual, drill the holes for the mounting bracket. The bracket must be perfectly horizontal – the boiler hangs on two points, and if it is tilted by 2–3°, the automatic air vent in the boiler will not work correctly. Use a spirit level. Drill into concrete or brick walls with a hammer drill; for aerated concrete (Ytong), use special anchors designed for aerated concrete – ordinary expansion anchors pull out of aerated concrete and the boiler can fall. This is not an exaggeration – it really happens.

Step 3 – Hydraulic Connection

Before connecting, make sure the heating system is empty and drained. The Logamax E213 has hydraulic connections at the bottom of the boiler as standard. The flow (hot water) and return (cold water from the system) are usually marked. Install a ball shut-off valve on each connection – this will later allow you to remove the boiler without draining the entire system. Seal threaded joints with quality thread sealing paste or hemp with paste (not just PTFE tape on larger threads).

A safety valve (set to 3 bar) must be included according to the diagram. The discharge pipe from the safety valve must be routed to a drain or a collection vessel – not onto the boiler room floor. If you leave it hanging freely and the valve opens (which is a normal occurrence), you will flood the equipment. The filling valve with a check valve allows the system to be filled directly with tap water.

Step 4 – Connecting the Expansion Tank

Every closed heating system must have an expansion tank to absorb the expansion of water when heated. The Buderus E213 has a built-in expansion tank with limited capacity (typically 6–8 litres depending on the model). For larger systems (a large house, a multi-storey building, a DHW cylinder), this is not sufficient and an external tank must be installed. Basic rule: expansion tank volume = approx. 10% of the total water volume in the system. For houses with underfloor heating, where the system may contain 150–200 litres of water, the built-in tank is significantly undersized.

Step 5 – Electrical Connection

This may only be carried out by an authorised person – a licensed electrician or an inspection technician. The boiler connects to a three-phase 3×400 V/N/PE network. The terminal block is accessible after removing the front cover. Follow the diagram in the manual (always check the current version of the documentation for the specific serial number). Basic procedure:

Disconnect the entire circuit at the distribution board (breaker off, secure with a label).
Use a multimeter to verify that there is indeed no voltage at the boiler end of the cable.
Phase assignment: L1, L2, L3 + N + PE according to the terminals in the boiler. Check the phase sequence with a phase sequence tester – an incorrect phase sequence does not cause an immediate fault, but it can cause the pump to malfunction in certain configurations.
The PE (protective) conductor must always be connected – never omit the earth connection.
Connect the control terminal block (for the thermostat, outdoor sensor, or eBUS communication) according to the chosen control configuration.

Step 6 – Filling the System and Venting

After completing the hydraulic and electrical connections, but before starting the boiler, the system must be filled with water and vented. Open the filling valve and let the water slowly fill the system – monitor the pressure on the gauge. The target filling pressure with cold water is typically 1.0–1.5 bar (check the system manual). Gradually vent all radiators and the boiler using the air vent valves. If you have underfloor heating in the system, venting is more thorough – air can continue to come out of the underfloor circuit for several hours after filling.

Check all joints and threads for leaks – before switching on. A wet spot at a pressure of 1.5 bar will be considerably worse at the operating pressure of 2.5 bar.

Step 7 – First Start-Up and Setting

Switch on the breaker in the distribution board. The boiler will go through an initialization sequence – the display will show the system status. Check the operating pressure (it should be in the green range of 1.5–2.0 bar during operation). Set the required flow water temperature according to the type of system:

Radiators: 55–75 °C (depending on the radiator size and the designed calculation temperature)
Underfloor heating: max. 45 °C (underfloor safety thermostat)
DHW cylinder (indirect): 55–65 °C for heating the cylinder

Set the thermostat or controller. For advanced control with an outdoor sensor, read the article Control and Output Regulation of the Buderus Logamax E213 Boiler – weather-compensated control significantly saves electricity and increases comfort.

Specific Situations from Practice

Renovating an Older System with Cast-Iron Radiators

One of the most common jobs: a customer replaces an old gas boiler with an electric Buderus. Cast-iron radiators are bulky, have high thermal inertia, and the system may contain 200–300 litres of water. In this case:

Check whether the existing safety valve (usually 3 bar) meets the requirements of the new boiler.
Re-dimension the expansion tank – the old one is likely no longer adequate.
Flushing the system is necessary – old mineral deposits damage the circulation pump and the flow sensor in the boiler. Use chemical flushing agents.
Consider installing a magnetic filter on the return – it captures magnetite (iron oxide) from steel pipes.

New Construction with Underfloor Heating

Here the procedure is cleaner, but watch out for other issues. Underfloor heating (a low-temperature system, max. 45 °C) together with domestic hot water preparation (min. 55 °C for hygienic safety) requires either a separate circuit or a mixing valve. The Logamax E213 does not have a built-in mixer in its standard version – for combined operation (underfloor heating + DHW cylinder), an external hydraulic manifold with a three-way valve is needed. Plan this in the design in advance, not afterwards.

Installation in a Low-Energy House

In a low-energy or passive house with a heat loss under 4 kW, the Logamax E213-4 model is sufficient. This combination makes perfect sense: a small boiler, a small water volume in the system, and a fast response to control. If you have mechanical ventilation with heat recovery (MVHR), the boiler usually only covers supplementary heating – it is not the primary heat source. You can find out more about this topic in the article Buderus Logamax E213 in a Low-Energy and Passive House – Is It Worth It.

Inspection, Handover, and Documentation

After installation, an initial expert assessment of the electrical installation (inspection) must be carried out in accordance with STN 33 1500 and STN EN 60364. The inspection report is essential not only for insurance purposes but also for any warranty claims – Buderus typically requires proof of professional installation. Without an inspection, you may lose the warranty.

Hand over the following to the customer:

The operating manual (in Slovak, if available)
The warranty card with confirmation of installation (date, signature, company stamp)
The electrical installation inspection report
A record of the first start-up with measured values (pressure, temperatures, current load)
The boiler wiring diagram placed directly in the boiler room (laminated sheet above the boiler)

Explain to the customer how to operate the boiler, set the temperature, top up the water pressure, and what to do if a fault occurs. This may seem obvious, but dozens of service call-outs occur every year because the customer did not know how to top up the system pressure and called an emergency service instead of simply refilling it. You can find out more about common faults in the article Common Faults of the Buderus Logamax Electric Boiler and Their Solutions.

Water Quality and System Protection

Electric boilers are more sensitive to water quality than gas boilers – the heating elements are in direct contact with the water, and hard water with a high calcium content forms limescale directly on their surface. A 1 mm layer of limescale reduces the heating element's thermal output by 10–15% and shortens its service life. Practical recommendations:

Water hardness above 20 °dH (German degrees): install a softener or use an inhibitor (for example, phosphate-based).
Closed systems with untreated water: after filling, the system does not need chemical treatment unless the water fails to meet hardness criteria, in which case consider semi-filtration additives.
Never use seawater or recycled wastewater.
For long-term shutdowns (for example, a summer cottage): either leave the system filled and set it to frost protection mode (the boiler has this mode), or drain and preserve the system according to the manual.

Safety Rules – What Must Not Be Done

From our field experience, we know that some customers (or unqualified "installers") do things that directly endanger safety. We explicitly warn against the following:

Never shorten the PE conductor – earthing protects against electric shock in the event of insulation failure.
Never block the safety valve – a blocked safety valve during system overheating = an explosion. This is not an exaggeration.
Never start the boiler without water in the system – dry starting will destroy the heating element within seconds. The Logamax does have a flow sensor, but do not rely on it as protection against improper filling.
Do not use extension cables to power the boiler – this is a fixed installation, not an appliance.
Do not modify the hydraulic connection without knowledge of the system – adding a three-way valve without correctly set hydraulics can cause circulation only in a small loop (short circuit loop) and overheating.

Frequently Asked Questions (FAQ)

Must the installation of the Buderus Logamax E213 electric boiler be carried out by an authorised company?

The hydraulic part can technically be carried out by a skilled DIY enthusiast with relevant experience; however, the electrical connection of the boiler to the 3×400 V network must always be carried out by a qualified electrician. After installation, an inspection of the electrical installation is required. Without proof of professional installation and inspection, the manufacturer may reject a warranty claim.

Can I connect the E213-14 boiler to an existing electrical connection with a 3×25 A main circuit breaker?

This depends on the total load of the house. The Logamax E213-14 model draws approximately 20 A at full output. If your house also has other appliances (stove, water heater, washing machine), the main circuit breaker may become overloaded when they run simultaneously. Have an electrician or designer calculate the diversified power load – this is the only correct approach.

What piping materials are suitable for the boiler's hydraulic connection?

Copper, threaded steel pipe, stainless steel, and multilayer pipes (PEX-Al-PEX, PE-RT) are all commonly used and compatible. Be careful when combining aluminium and copper without inhibitors – electrolytic corrosion can occur. PEX or PE-RT pipes are the standard for underfloor heating. Plastic pipes (PP-R) require professional welding and proper expansion allowance.

What should I do if the boiler shows an error code after installation?

First, look up the error code in the manual (every code is described there). The most common causes after installation are: low water pressure in the system (air in the system, insufficient filling), incorrect phase sequence, or incorrect wiring of the temperature sensor. You can find a more detailed overview in the article Common Faults of the Buderus Logamax Electric Boiler and Their Solutions. If the code persists after checking all the basics, contact an authorised Buderus service centre.

Is it necessary to replace the existing piping in the house when installing the E213-6 or E213-8 boiler?

This depends on the diameter and condition of the existing pipes. Both the Logamax E213-6 and the E213-8 are typically dimensioned for systems with flow rates of around 0.3–0.6 m³/h, which most existing piping in family houses can handle. If the pipes are old and in poor condition, or if the diameters are very small (½" or less), reworking makes sense. Always check the original heating system design.

How long does the installation of a Buderus Logamax electric boiler take in a typical family house?

When replacing an existing boiler (same location, existing piping in good condition): an experienced two-person team (installer + electrician) can complete the entire process, including the first start-up, in 4–6 hours. For a new installation, where new piping and a new electrical cable from the distribution board need to be run, allow 1–2 working days. If the distribution board is also being replaced or the main circuit breaker needs to be increased by the distributor, the whole process can take a week or longer.

Conclusion – Installation Deserves the Same Attention as Product Selection

The Buderus Logamax E213 electric boiler is a technically excellent product with a long service life – but only if it is correctly installed. An undersized cable, a missing expansion tank, a neglected magnetic filter, or a skipped inspection – these are things that may not cause problems in the first year, but three years later they can cause a failure that neither the manufacturer nor the insurance company will pay for. Investing in proper installation is much cheaper than the repairs that result from neglecting it.

If you are considering a specific model, take a look at our products in the Buderus Logamax category – from the compact E213-4 suitable for low-energy houses to the powerful E213-10 and E213-14 for larger buildings or combination with a large hot water cylinder. Every model deserves proper installation – and this guide gives you a solid foundation for it.

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