Step-by-step installation of the Viking water heater

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Installation of a Viking Tap Step by Step: Complete Practical Guide

Replacing or installing a new tap is one of those tasks that an experienced DIYer can manage without calling a plumber – but only if they know exactly what they're doing. From experience, I know that many unnecessary problems arise with taps not because the installer is clumsy, but because they skip some seemingly trivial step: forgetting to seal the thread, not tightening the flexible hose enough, or confusing the left and right connections. This article therefore goes through the entire installation process in detail, with technical details that are often omitted in brief instructions.

We cover the installation of a wall-mounted lever tap (type with two connections G3/8" or G1/2"), a built-in basin tap, and a shower/bathtub tap – the types you will encounter most often with Viking taps. If you're not yet sure which type of tap you actually need, I recommend reading the article How to choose Viking taps for your bathroom and kitchen in our Knowledge Center, where you will also find an overview of the differences between the various ranges.

What you will need – tools and materials

Before the actual installation, prepare everything within reach. Nothing slows down work more than running to the store in the middle of the job when you have wet hands and the water is turned off.

Tools

Adjustable wrench (spanner) – jaw width at least 35 mm, ideally 45 mm. For tightening the connecting nuts of angle valves and flexible hoses.
Tap wrench (basin tap wrench) – long rod with flat or star-shaped end, designed for tightening the fixing nut of the tap from below. Without it, you won't reach the narrow space under the basin. It is also sold as a "basin wrench" or "tap wrench for narrow spaces".
Combination pliers (Multigrip/Mole grips) – for holding the top part of the tap while tightening the bottom nut, but only with protection (fabric, hose), to avoid scratching the surface.
Flat and cross screwdrivers – for removing covers and sockets.
Knife or utility knife – for removing old silicone and seals.
Bucket or tray – for collecting residual water when disconnecting hoses.
Towels and paper towels – for cleaning the work area.

Materials and consumables

Teflon tape (PTFE tape) – width 12–19 mm, thickness at least 0.075 mm. Cheaper tapes tear and do not provide sufficient sealing.
Flax seal (packing) + paste – an alternative for older types of metal threads with larger tolerances. For new Viking taps with precise threads, PTFE is sufficient.
Flexible connecting hoses G3/8" – G1/2" – length typically 30–50 cm, depending on the distance from the angle valve to the tap. Always buy new – old hoses with cuts or swollen rubber are a potential flood hazard.
Neutral acrylic sealant or sanitary silicone – for sealing the socket against the wall (for shower/bathtub taps).
Flat gaskets – rubber flat gaskets for flexible hoses, diameter 13–15 mm. A set of 10 pieces costs a few euros and will save you from having to run back to the store.

Phase 1: Preparation and turning off the water

It may seem trivial, but errors in this phase cause the most accidents. Turn off the water at the angle valves under the sink or bathtub – turn the valve clockwise until it stops. If the angle valves are missing or rusted and cannot be closed, you must shut off the main shut-off valve of the apartment or house.

After closing the valve, open the tap fully and let the remaining water drain from the pipes. Then hold a bucket under the flexible hoses – when disconnecting them, another 0.5–2 dl of water will still run out, depending on the pressure in the system and the length of the piping.

Check the water pressure in your home – the ideal working pressure for Viking taps is 0.15–0.5 MPa (1.5–5 bar). If you have a higher pressure in the network (typically in apartment buildings around 6–8 bar), install a pressure-reducing valve before the tap. Taps under overpressure suffer from rapid wear of the cartridge and leakage. The topic of selecting a cartridge is also covered in the article Replacing the seal and cartridge in Viking taps.

Phase 2: Removing the old tap

If you are installing a tap in a new location (new build, renovation), skip to Phase 3. If you are replacing an existing tap, proceed as follows:

Unscrew the flexible hoses from the bottom of the tap – turn clockwise from above (from the nut's perspective), which is counter-intuitive from below: turn the wrench to the left. Immediately place a tray under the hoses.
For a basin tap: loosen the fixing nut from below (usually a plastic or brass nut M52 or similar). Use a tap wrench.
Pull the tap upwards through the hole in the basin.
Unscrew the nuts of the flexible hoses from the threads of the angle valves and completely remove the hoses.
With a knife or utility knife, remove the old silicone/seal around the hole in the basin. Clean and dry the surface – the new tap must sit on a clean, flat base.

Phase 3: Sealing of threads and preparation of flexible hoses

Proper sealing of the threads is the most critical step, which determines whether the connection will be tight five minutes after installation and five years later. The most common mistake is applying too little PTFE tape – you save a few seconds and pay for it with a wet stain on your neighbor's ceiling.

How to correctly wrap Teflon tape

Clean the threads of the angle valve (usually G3/8" external) from old remnants of sealing. Place the end of the PTFE tape at the base of the thread and wrap it in the direction of the thread (when looking at the end of the thread, turn the tape clockwise). Wrap 8–12 layers evenly, without gaps. The tape should be taut, not loosely draped – pull it slightly while wrapping. At the end, press the tape firmly against the thread so it does not peel off.

For G1/2" threads (larger connections for bath faucets), wrap 10–15 layers. If you are using hemp sealing rope with paste, apply a thin layer of paste to the thread, then wrap the rope (not too much – excess can clog the faucet filter) and tighten.

Flexible hoses – selection and inspection

I recommend always using new flexible hoses. Check:

Diameter of the fittings: G3/8" – G1/2" (or G3/8" – G3/8", depending on the faucet)
Length: measure the actual distance from the angle valve to the faucet connection; add 5 cm of reserve for a natural curve. Typical ranges: 30, 35, 40, 50 cm.
Flat rubber seals in the fittings: they must be present and undamaged. Flat seals ensure sealing at the nuts (not thread sealing, so PTFE tape is not applied to the hose nuts).
Winding: stainless steel (316L or similar) is more durable than aluminum. For faucets in a wet environment (bath, shower), always choose stainless steel.

Phase 4: Installation of the new Viking faucet – single-lever wall-mounted faucet

I describe the procedure for the most common type – a single-lever wall-mounted sink faucet with one opening in the sink and two lower connections G3/8".

Step 4.1: Mounting the faucet into the opening

Check whether the faucet comes with a rubber seal (washer) – most Viking faucets include it in the packaging. Slide the seal onto the threaded rod of the faucet so that it lies on the bottom of the faucet body. If you have a modern sink made of stone, marble, or thick ceramic, check the height of the threaded rod – it must protrude at least 20 mm below the sink for the washer and nut to be inserted.

Mount the faucet into the opening from above in the correct orientation (the outlet points above the drain, the lever points toward the user). Ask someone to hold the faucet from above while you work from below.

Step 4.2: Sliding the washer and nut from below

From below, slide the plastic mounting washer onto the threaded rod – it has a larger diameter than the sink opening. Then slide on the mounting nut and start tightening it by hand. When you feel resistance, continue with an installation wrench. Tighten evenly, check from above that the faucet is not crooked. The nut must be tightly tightened – the faucet must not rotate or wobble, but do not over-tighten (the plastic nut can crack under excessive force).

Step 4.3: Connecting the flexible hoses

Connect the flexible hoses by hand to the lower connections of the faucet – most Viking faucets have markings H (hot) and C (cold). Traditional layout: left connection = hot water, right connection = cold water. This is the European standard (EN 15091), which applies almost always, but always verify the direction of the angle valves in the wall as well.

Connect the hoses by hand, then tighten them with a wrench by an additional ¾ to 1 turn. Do not over-tighten – the hose nuts are mostly made of brass or plastic and the threads can be stripped. Warning: the hoses must not be sharply bent or twisted into a spiral – there must be a natural curve. A bent hose = restricted flow and rapid failure of the inner rubber.

Apply the same procedure to the other end of the hoses – the connections of the angle valves. Here the thread is external (G3/8" external on the valve), the hose nut is internal. Sealing is ensured by a flat rubber ring in the hose nut, not by PTFE tape on the valve thread itself.

Phase 4B: Installation of the Viking wall-mounted shower/bathtub mixer

Wall-mounted mixers (for bathtubs and showers) have a different installation procedure because the connections are directly in the wall – in the form of two outlets with an external G1/2" thread and an axial distance of 150 mm (standard). Check this before purchasing the mixer – some older installations have a spacing of 100 mm or 120 mm, which is incompatible with standard mixers. For more information on dimensions, see the article Dimensions and connection of Viking mixers: what to check before purchase.

Installation procedure for a wall-mounted mixer

Wrap PTFE tape around the wall outlets (10–15 layers for a G1/2" thread).
Check the even protrusion of both outlets – ideally the same length, at least 8 mm beyond the wall surface to allow for the installation of the gasket and escutcheon. If the outlets are too deeply embedded, you will need to use extension nipples.
Slide the mixer escutcheons onto the outlets. The escutcheons should rest against the wall and cover the tiles around the outlets.
Slide the mixer body onto both outlets simultaneously and tighten the body nuts onto the threads. Tighten alternately on the left and right – a few turns at a time, to prevent the mixer body from twisting.
Tightening: usually hand-tightening followed by an additional 1.5–2 turns with a wrench is sufficient to ensure the escutcheon sits tightly against the wall. Do not over-tighten – the ceramic tile may crack.
If there is a gap between the escutcheon and the wall (e.g., due to uneven tiling), fill the gap with neutral sanitary silicone. Match the color to the tile.
Install the outlet (pipe with a spout), shower hose, and head according to the mixer instructions.

Phase 5: Commissioning and leak check

This is the phase where many DIY plumbers make a mistake: they open the water fully and immediately leave. The correct procedure is slower.

Startup procedure

Open the angle valve slowly, only a quarter turn. Allow the pressure to build up gradually.
Visually inspect all connections – dry or wet? If any moisture is detected, immediately close the valve, identify the location, and reseal or tighten.
If everything is dry, open the valve fully.
Open the mixer – first only for cold water. Let it run for 30 seconds, then switch to hot and let it run for 30 seconds.
Check the flow: if it is weak, the outlet aerator is likely clogged. Remove it, rinse it under water, and reinstall it. The aerator may have PTFE tape residue or rust flakes from the pipe that were blown in during installation.
Let the mixer run for 2–3 minutes and again check all connections for moisture – including underneath the sink.

Specific situations from practice: problems and their solutions during installation

Over the years of practice, I have seen a number of situations that are not covered by standard instructions. Here are the most common ones:

Problem: angle valve leaks or cannot be closed

An old angle valve with hardened sealing rubber or a corroded stem is common in apartments older than 20 years. If the valve cannot be closed tightly, you must shut off the riser or main shut-off valve. Replace the angle valve with a new one – extra work, but necessary. PTFE sealing is also required on the riser branch thread.

Problem: the threads in the wall outlets are dirty or damaged

Remove old PTFE tape and debris with a wooden or plastic stick – never with a metal tool, to avoid damaging the threads. If the thread is partially damaged (stripped), try so-called "thread repair paste" (thread compound). In case of serious thread damage, professional help is required (welding a new nipple).

Problem: the mixer rotates in the hole after tightening the nut

This happens when the hole in the sink is larger than the mixer body diameter. The solution is to add a larger plastic or brass washer (escutcheon) on top and bottom, or use a special adapter escutcheon supplied as an accessory. Some Viking mixers include an anti-rotation washer in the packaging – look for it among the packing materials.

Problem: weak pressure on hot water after installation

Most common cause: during disconnection of the old hose, debris entered the pipe and clogged the boiler's thermostatic valve or the mixer inlet filter. Solution: clean the aerator, check the hot water inlet filter (if you have one). If the problem persists, the cause may be in the mixer cartridge – the filter before the cartridge may be clogged. Details can be found in the article Common Viking mixer faults and how to eliminate them.

Problem: aerator sputters or has low flow

A clogged aerator is extremely common after any installation, as sediment is released from the pipe during work. Unscrew the aerator (usually by hand, or with a coin or flathead screwdriver), remove the filters, and rinse them under water. If it is limescale, soak the filters in white vinegar for 30 minutes.

Thermostatic Viking mixer – differences in installation

Thermostatic Viking mixers have the same connection system (G1/2", axial distance of 150 mm for wall-mounted types), but require a few additional steps. A comparison of lever and thermostatic mixers can be found in the article Lever vs. thermostatic Viking mixer: which is suitable for your case.

Fixed connection position: hot water must always be connected to the left (when viewed from the front of the mixer) and cold water to the right. Reversing them could damage the thermostatic mechanism.
Minimum pressure difference: thermostatic mixers require a minimum operating pressure of 0.1–0.15 MPa (1–1.5 bar) on both branches. If hot water is supplied from a storage heater with low pressure, the thermostat may not regulate properly. Check the pressure at the boiler.
Maximum temperature setting: after installation, set the thermostat's maximum temperature limiter (red stop) to a maximum of 38–42 °C for households with children or seniors. The procedure is described in the instructions for the specific mixer.
Cartridge flushing: before the first startup, open the mixer without the thermostat handle installed and flush the system for at least 2 minutes on each branch – this protects the thermostatic valve from rust contamination.

Installation of the Viking kitchen faucet – specifics

Kitchen faucets are installed into a sink or a sink with a countertop. The procedure is the same as for a lavatory faucet, but with a few practical differences:

Holes in stainless steel sinks are usually 35–40 mm in diameter – check the compatibility of the faucet body (standard is a flange with an outer diameter of 65–80 mm).
Countertops are thicker than ceramic lavatories – the threaded rod of the faucet must be of sufficient length (at least 40 mm protrusion under the countertop for a plastic washer and nut). If the rod is too short, there are extension adapters available.
With faucets featuring a pull-out spray head, make sure that the hose can freely pass through the sink hole even when the head is fully extended. The hose must not be guided through sharp metal edges of the sink – it would gradually get cut over time.
If the faucet includes a magnetic parking system for the head (as part of the faucet), install the magnets exactly according to the instructions – they must be centered relative to the outlet, otherwise the head will not park magnetically.

What to do after installation: first weeks of operation

Immediately after installation, check for leaks again after 24 hours – some leaks may appear only after the seals have hardened and settled under pressure. Gently rub dry paper towels around all connections: a wet towel = a leak.

After 2–4 weeks, you can (and I recommend) clean the aerator again – a second wave of debris from the pipes, released during the first flow, may have settled on the screen. Regular aerator maintenance every 6 months prolongs the life of the faucet and maintains full flow. More on maintenance can be found in the article Cleaning and maintenance of Viking faucets: how to extend their lifespan.

Also check the adjacent silicone or flange seal – if the faucet body slightly rotated during the first intensive use, the silicone seal may have cracked. In such a case, apply a new bead of sanitary silicone after cleaning the surface.

Frequently asked questions (FAQ)

Do I have to replace the flexible hoses when replacing the faucet?

Technically, you are not required to, but from a practical standpoint, I always recommend replacing the hoses together with the faucet. Old hoses have hardened rubber seals and swollen inner rubber, which can cause later leaks. New hoses cost only a few euros and will protect you from costly water damage. Always measure the length and type of hose on-site before purchasing.

How many layers of PTFE tape are enough?

For G3/8" threads (angle valves), 8–12 layers of quality PTFE tape with a thickness of 0.075–0.1 mm is sufficient. For G1/2" threads (bath faucets, wall outlets), wind on 10–15 layers. If in doubt, it is better to add more layers – excess PTFE will not damage the joint, it will only make it stiffer when tightening.

Can I install a Viking faucet myself without an installation license?

Yes, replacing a water faucet (including flexible hoses and angle valves) is a common household maintenance task that does not require a professional license. An installation license is legally required for work on household plumbing (pipes in the wall, risers, supply from a shared pipe). As long as you are working from the angle valve towards the faucet, you are in the safe zone of routine home repair.

Why is water dripping from the outlet after installation when the faucet is closed?

There are two possible causes: either the cartridge is damaged (crack, worn sealing surfaces) – which happens only rarely with a new faucet, or the water pressure in the pipes was too high and damaged the cartridge right at the first start-up. Check the water pressure – it should be no more than 5 bar. If the faucet is new and leaks immediately after installation, contact the seller – it is likely a return case. Cartridges and their replacement are discussed in detail in the article Replacing seals and cartridges in Viking faucets.

What is the difference between G1/2" and G3/8" connections? Can they be mixed?

G3/8" and G1/2" are two different sizes of pipe threads – G3/8" has an outer thread diameter of about 16.7 mm, G1/2" about 20.9 mm. They cannot be physically interchanged (you cannot screw a G3/8" nut onto a G1/2" thread or vice versa), so when buying hoses, just make sure that each end matches the thread size on the faucet and on the angle valve. Most Viking lavatory faucets have bottom connections of G3/8", angle valves also have G3/8" external, bath faucets have G1/2". A detailed overview of dimensions can be found in the article Dimensions and connections of Viking faucets: what to check before purchase.

Do I have to wait any time before first use after installation?

No, with standard installation using PTFE sealing, you can use the faucet immediately. The only exception is if you used sanitary silicone to seal the flange against the wall or around the hole in the lavatory – in that case, wait 24 hours for the silicone to cure before wet operation. Always make sure the surfaces are dry and degreased before applying silicone.

Conclusion: proper installation is the basis for long faucet life

Proper installation of a Viking water faucet is not rocket science, but it is a craft that requires the right procedure, the right materials, and patience. From experience, 80% of faucet problems (leaks, scratches, poor flow) arise directly from installation and could have been avoided. Every step in this guide – from properly winding the PTFE tape, through the natural bend of the hoses, to slow start-up with inspection – will protect you from future problems and extend the life of your faucet for many years.

If you are interested in specific Viking faucet models available for your project, visit the main Viking water faucet category on atria.sk, where you will find the full range – from lavatory lever faucets through shower sets to thermostatic models for the bath.

Do you have a question about this topic?

Not sure or dealing with a specific situation in your home? Write to us – we are happy to help.