- The boiler
- Cv-ketel
- Hot-water class
- CW-klasse, on the Gaskeur label
- Filling valve
- Vulkraan
- Call-out charge
- Voorrijkosten
The boiler itself
| Dutch | What it means |
|---|---|
| Cv-ketel | The boiler. Cv stands for centrale verwarming, central heating. People often just say “de ketel”. |
| Combiketel | A combi boiler: one appliance for both the heating and the hot water. |
| HR-ketel | A high-efficiency (hoog rendement) condensing boiler. It gets extra heat out of the flue gases by letting the water vapour condense on the heat exchanger. |
| HR107 | The old name on the label. Since September 2015 it just says HR. The 107 stood for at least 107% efficiency at low output. |
| Gaskeur | The Dutch quality label on gas boilers, issued by the testing institute Kiwa. |
The HR details come from Consumentenbond. An HR boiler is most efficient when it runs on a low flame, which is why the thermostat matters.
CW-klasse: how much hot water
The CW class on a combi boiler’s Gaskeur label tells you how much hot water it delivers. A higher number means more hot water, faster. Consumentenbond describes the classes like this:
| Class | Hot water |
|---|---|
| CW3 | At least 6 litres a minute at 60°C, or 10 litres at 40°C. Enough for a normal shower, not a big rain shower. |
| CW4 | At least 7.5 litres a minute at 60°C, equal to 12.5 litres at 40°C. Fills a 120-litre bath within 11 minutes. |
| CW5 | Fills a 150-litre bath at 40°C in 10 minutes. Two water-saving showers at once are no problem. |
| CW6 | As CW5, and you can also run two hot taps fully at the same time. Has a built-in storage tank, so it is bigger and uses more energy. |
Bigger isn’t automatically better. Consumentenbond notes that a lower class often has a lower minimum output, so it heats more evenly. When I quote for a new boiler, I match the class to your shower, bath and household.
Parts you’ll hear about
| Dutch | What it means |
|---|---|
| Vulkraan | The filling valve you use to top up the heating water when the pressure drops. My pressure guide shows how. |
| Expansievat | The expansion vessel. Heating water expands as it warms up, and this vessel takes up the extra. A faulty one can make the pressure rise and fall. |
| Warmtewisselaar | The heat exchanger, where the heat of the burning gas passes into the water. |
| Rookgasafvoer | The flue that takes the combustion gases outside. An HR boiler is a closed appliance, with a separate pipe bringing in outside air. |
| Druk | Pressure, shown in bar on the boiler’s gauge or display. |
Look, don’t open: the casing stays on. Anything inside is work for an engineer.
Thermostat words
| Dutch | What it means |
|---|---|
| Kamerthermostaat | The room thermostat. |
| Klokthermostaat | A programmable clock thermostat. |
| Aan/uit | On/off control: the boiler burns fully or not at all. |
| Modulerend | Modulating: the thermostat tells the boiler how hard to burn. |
| OpenTherm | A cross-brand standard that lets a boiler and thermostat talk, so the boiler can modulate. See the OpenTherm Association. |
| Thermostaatknop | A thermostatic radiator valve. |
More in my guide to choosing a thermostat.
Other ways to heat a home and its water
Warmtenet or stadsverwarming is district heating. Hot water flows from a central source through underground pipes. In your home, an afleverset (delivery set) with a heat exchanger passes that heat to your radiators and taps. Milieu Centraal says it usually sits in the meterkast, where the gas meter used to be, and that you nearly always rent it with maintenance included. So faults go to your heat supplier first.
Geiser is a gas water heater that heats tap water as it flows, often in the kitchen. It burns gas like a boiler, so the same rules apply. The government says installation, maintenance and repair must be done by a certified company, and advises a CO alarm.
Warmwaterboiler is a hot-water cylinder: a tank that stores heated water. To a Dutch speaker, “boiler” means this, not the cv-ketel.
Around the house
Meterkast is the meter cupboard, usually near the front door. It holds the electricity meter and fuse box, and in most homes the gas meter too, with the main gas tap.
Hoofdkraan is the main water stop tap, usually by the water meter. Find it before you need it: it’s the first thing to close in a leak.
On a quote or invoice
| Dutch | What it means |
|---|---|
| Offerte | A quote. My guide to reading a Dutch quote covers the rest of the words on one. |
| Voorrijkosten | The call-out or travel charge. I don’t charge one: it’s €114.95 incl. BTW per hour from the start. |
| Onderhoudsbeurt | A service visit. My boiler service is €145 incl. BTW plus materials. |
| Storing | A fault or breakdown. A storingscode is the fault code on the display. |
| BTW | Dutch VAT. Check whether a price is inclusief (including) or exclusief (excluding) BTW. All my prices include it. |
Need a hand with yours?
Not sure what you’ve got? Send me on WhatsApp a photo of the boiler’s label, your question and your postcode. For a fault, see boiler repair.
If you smell gas, leave the property and call 0800 9009 from outside. If a CO alarm sounds or you suspect carbon monoxide poisoning, get everyone outside and call 112.
Common questions
It is the hot-water class of a combi boiler. Consumentenbond says a CW4 gives at least 7.5 litres a minute of 60°C water at the kitchen tap, equal to 12.5 litres at 40°C, and fills a 120-litre bath within 11 minutes.
They mean the same kind of boiler. Since September 2015 the Gaskeur label says HR instead of HR107. The 107 stood for at least 107% efficiency at low output, under the old way of calculating.
A geiser is a gas appliance that heats tap water as it flows. A warmwaterboiler stores hot water in a tank. Neither heats your radiators; that is the cv-ketel's job.
The call-out or travel charge. I don't charge one; my rate is €114.95 incl. BTW per hour.
