Water,
heat,
flow.
A complete Danish reference work on plumbing & HVAC — from water velocity and flow to heat output, pumps, expansion and drinking-water hygiene. Read the articles. Use the calculators. Ask the assistant. Same login as technical insulation.
13
Calculators
26
Articles
∞
Questions
Closed heating circuit: circulation pump → flow 70 °C → heating coil → return 50 °C. Copper arrows show the water's flow direction; the output follows P = q · c · ΔT.
§ 01 — What you can do here
Read, calculate, look up — or ask.
Eight tools from hydraulics to assembly — for apprentices, fitters and installers.
Tools in the trade
§ 02 — About the trade
Plumbing
Plumbing and heating is the trade of water, heat, drainage and gas in buildings — from the drinking water installation and the heating system to the soil stack and the gas pipe. A plumber sizes, joins and tests pipe systems, and the work is governed by standards: drinking water, gas and drainage may only be carried out by authorised companies. The trade covers new build, renovation and service — from the bathroom in a detached house to heat pumps, district heating and ventilation in larger buildings.
Questions about the trade
What does a plumber do?
A plumber installs and maintains water, heating, drainage and gas — pipes, fittings, pumps, cylinders, radiators and valves. The work begins with measuring and sizing: flow, velocity and pressure decide the pipe dimension before the first pipe is joined. The craft itself is joining pipe in the right material — soldering copper, press fittings, threaded joints and drainage — and an installation is only finished once it has been pressure tested, flushed through and commissioned with documentation. The working day moves between the bathroom in a detached house, heating and ventilation plant in larger buildings, and fault finding on systems that do not heat or that leak.
What rules apply to drinking water and drainage?
DS 439 is the Danish standard for water installations and sets out sizing, material selection and backflow prevention in its 2024 edition. DS 432:2020 covers drainage installations — foul water, rainwater, traps and backflow valves — and both are read together with the Danish building regulations, BR18. Backflow prevention is chosen from the fluid category in DS/EN 1717, which Rørcenter-anvisning 015 renders into Danish practice. Against legionella the tool is temperature: the guidance from Statens Serum Institut on hot domestic water points to 60 °C in the cylinder and 50 °C at the furthest tap, because the bacterium thrives in stagnant, lukewarm water.
How do you size pipes and heating systems?
Sizing in plumbing is a calculation between flow, velocity and pressure loss. Velocity follows the continuity equation v = Q/A, where A is the internal cross section of the pipe — choose the dimension too large and the water stands almost still, giving deposits and increased legionella risk; choose it too small and you get noise and erosion. In water-borne heating systems the output comes from the energy balance P = q · c · ΔT, where the specific heat capacity of water is about 4.19 kJ/(kg·K). The system is sized to DS 469, the pressure loss along the run is calculated with Darcy-Weisbach, and the pump is then selected against its duty point on the curve.
When does plumbing work require authorisation?
Work on drinking water, gas and drainage may only be carried out by authorised companies. The requirement follows from the Danish Authorisation Act, and approval is administered by Erhvervsstyrelsen, into which Sikkerhedsstyrelsen was merged in January 2026. The route to company authorisation runs through a journeyman's certificate, work experience and the authorisation training, and every authorised company must have an approved quality management system (KLS) that is reviewed every second year. Sewer work is a separate track with its own master sewer examination and its own KLS — you can be authorised for water and gas without being a sewer master. Gas work is additionally regulated by the gas order, BEK nr. 1702/2025.
How do you become a plumber?
VVS-energiuddannelsen is the Danish vocational programme for the trade: a basic course at a vocational college followed by a main course that alternates between school and an apprenticeship in a plumbing company, with pay during the practical periods. The programme lasts up to 4 years and 9 months and has four specialisms: VVS-energispecialist, VVS-installationstekniker, VVS og blikkenslager and VVS-ventilationstekniker. With the journeyman's certificate you can work as a fitter or service technician and build on towards authorised VVS-installatør. Heat pumps, district heating and ventilation take up more and more room, so a large part of the subject matter today is energy and indoor climate.
Based on: DS 439 · DS 432 · DS 469 · DS/EN 1717 · BR18 · Autorisationsloven · BEK nr. 1702/2025 · SSI's vejledning om legionella · Darcy-Weisbach
§ 03 — Read now
Featured articles
Featured articles
All articles →§ 04 — Tools
Work it out.
Enter the flow and the temperature difference between supply and return — and get the transferred heat output and the mass flow in seconds. The formula P = q · c · ΔT uses the material constants of water near room temperature.
Open calculators→Example · Heat output from water flow
70/50 °C · ΔT 20 K
P = q·c·ΔT
§ 05 — Trade in Action
How it looks craftsmanship.
Three classic procedures from the trade — drawn as blueprint: radiator, floor heating and pipe pressure loss.
Work processes
Radiator is heated
The plumber adjusts the thermostatic valve: hot supply in from the left, cold return out to the right, and heat radiates into the room.
Floor heating is installed
The installer lays 16 mm floor heating pipe in a meander pattern on the insulation slab, secures it and runs the circuits up to the distribution cabinet.
Pipe pressure drop is measured
Two manometers — one before and one after stretch — show how friction and local losses in bends lower pressure through pipe
§ 06 — Next step
One question
in Danish.
The AI assistant can size flow and heating, explain pumps and expansion, and help with drinking water and regulations. Write to it as you would to a colleague.
Ask a questionSafety
Come home in the same state
I VVS-faget har du en flamme i den ene hånd og vand under tryk i den anden. Du lodder tæt op ad træværk, du åbner ventiler på anlæg der er kogende varme, og du stiger ned i brønde hvor luften kan slå dig ihjel på et minut. Faren er sjældent dér hvor du kigger — den er i revnen bag røret, i gassen der ligger i bunden af brønden, og i den gamle isolering du river af.
Safety course
48 modules · 441 min · 4 farer der kan dræbe
§ — Where can you read about Plumbing?
Find a school nær dig.
VVS-energiuddannelsen is offered at 17 places in the country. The list is informational — always check the latest and complete offering on the Education Guide's vocational education map.
Schools offering the programme
Hovedstaden
03- TEC – Technical Education Copenhagen — Frederiksberg
- U/NORD — Hillerød
- TEC — Søborg
Sjælland
04- CELF — Nykøbing Falster
- EUC Sjælland — Køge
- Roskilde Tekniske Skole — Roskilde
- ZBC (Zealand Business College) — Næstved
Syddanmark
05- HANSENBERG — Kolding
- EUC Syd — Sønderborg
- Rybners — Esbjerg
- Syddansk Erhvervsskole (SDE) — Odense
- EUC Syd — Aabenraa
Midtjylland
04- AARHUS TECH — Aarhus
- Learnmark Horsens — Horsens
- Herningsholm Erhvervsskole — Herning
- Mercantec — Viborg
Nordjylland
01- Techcollege — Aalborg