You do not replace a central heating boiler every year, and that is why the question often comes unexpectedly: during a service the engineer says the boiler is on its last legs, or the boiler breaks down on a cold morning. Then you have to choose at short notice between a new HR boiler, a hybrid heat pump alongside the boiler or going fully electric straight away. This article helps you at that moment: how to recognise that the boiler is due for replacement, what is currently allowed, which options there are, who is allowed to do the work and what a good heating engineer or installer checks. If you want to look into the heat pump itself in detail, also read Having a heat pump installed: hybrid or all-electric.
When is a central heating boiler due for replacement?
There is no fixed age at which a boiler must be replaced, and legally a working boiler never has to go. According to the Rijksoverheid (Dutch central government), a central heating boiler lasts about fifteen years, and according to Milieu Centraal (the Dutch independent information centre on energy and environment), a well-maintained boiler lasts longer and has fewer breakdowns. Milieu Centraal recommends that with a boiler of twelve years or older you already start looking at its successor, so that you do not have to choose under time pressure. Signs that the moment is approaching:
- Age. The boiler is fifteen years or older, or is approaching that age.
- More frequent breakdowns. The boiler regularly cuts out, often has to be reset or keeps losing pressure, and every engineer's visit turns up a new fault.
- Parts. The engineer reports that parts for your model are no longer available or hard to get. A repair can then take a long time, or no longer be possible.
- Hot water. The hot water fluctuates in temperature or takes longer and longer, while nothing has changed in your usage.
- Efficiency. An old boiler, and certainly a VR (improved efficiency) or conventional boiler without condensation, gets less heat out of the same gas than a modern HR boiler. HR stands for hoog rendement (high efficiency): the boiler also uses the heat from the water vapour in the flue gases.
- Safety. If you see soot, a yellow or orange flame on an open-flued appliance, or your CO detector goes off, switch the appliance off, ventilate and have it checked immediately. You can read what else you need to know about detectors and servicing in CO detectors and boiler servicing: what is mandatory and what is sensible.
A sensible rule of thumb: at the next service, have the engineer give an honest assessment of the condition of the boiler and whether a major repair is still sensible at this age. Preferably ask for that in writing, so that you can fall back on it later.
Plan it before the boiler breaks down
Milieu Centraal recommends not waiting until the boiler has broken down: you are then left in the cold, you want a new one immediately and you have no time to compare the options properly. That applies all the more in winter, when installers are handling the most breakdowns and their schedules are full. A new HR boiler can often be fitted quickly in an emergency, but a hybrid or fully electric heat pump requires a home visit, a calculation, sometimes changes to the electrics and a delivery time. If you start in spring or summer, you can calmly compare quotes and still have all the options open.
While you are looking into it, also check what your municipality is planning for your neighbourhood. If a heat network is coming in the next few years, a large investment in your own heat pump may not be the most logical step. Milieu Centraal mentions the municipality's heat plan as something to check in advance.
Can you still buy a new central heating boiler?
Yes. In 2022 the Dutch government announced that from 2026, at least a hybrid heat pump would become the standard when the central heating boiler is replaced, if the home is suitable for it. That standard never materialised: the new coalition scrapped the plans in 2024 in its outline coalition agreement (hoofdlijnenakkoord), and the government then opted for incentives instead of an obligation. Fitting a new HR boiler is therefore simply allowed at the time of writing.
On 7 October 2026, however, the current government announced a new intention: from 2029, a smart hybrid heat pump should become the standard when the central heating boiler is replaced, for homes that are not or will not be connected to a heat network. According to the letter to parliament (Kamerbrief), blocks of flats and listed buildings are excluded for the time being. That plan is still being worked out and has not yet been laid down in legislation. If you fit a new boiler now, it is sensible to take a later hybrid heat pump into account, for example by choosing a boiler that can work together with a heat pump and keeping space free for an outdoor unit. Check the current state of affairs on rijksoverheid.nl.
Option 1: a new HR boiler
The simplest replacement is a new HR boiler in the same place. You keep your radiators, your gas connection and your way of heating. A few choices determine whether the new boiler suits you well.
Combi boiler or boiler with a hot water cylinder
A combi boiler provides both the heating and the hot tap water. If you currently have a separate water heater next to a central heating boiler that only heats, Milieu Centraal advises replacing both in one go with a combi boiler; that saves energy and is simpler to maintain. A boiler with a separate hot water cylinder keeps a supply of hot water in store and can be convenient for a large household, several bathrooms or a bath that needs to fill quickly. If you want to move to a hybrid heat pump later, the choice of hot water supply can also make a difference; discuss this with the installer.
Hot water class: no bigger than necessary
The energy label of a central heating boiler uses the letters S, M, L and XL to indicate how much hot water the boiler can deliver. In addition, many manufacturers and installers use the Dutch Gaskeur CW label, with classes from CW1 to CW6: the higher the class, the more the boiler can handle: from just a kitchen tap at CW1 to filling a bath or two taps at the same time at CW6. According to Milieu Centraal, a boiler that delivers a lot of water usually has a lower efficiency for hot water and therefore uses more gas. A large class is mainly needed if you use two showers at the same time or often fill a bath. Tell the installer how your household uses hot water, instead of taking the largest version as standard.
Modulating thermostat and smart controls
A modern HR boiler can turn down its output when little heat is needed. That only works properly with a modulating thermostat, which tells the boiler how much heat is needed instead of just switching it on and off; Milieu Centraal explicitly recommends such a thermostat. Weather-compensated control with an outdoor sensor adjusts the flow temperature to the outside temperature, so that on mild days the boiler works with cooler water and condenses more. Also ask the installer to set the maximum flow temperature as low as your home allows: in a reasonably to well insulated house, according to Milieu Centraal, 50 or 60 degrees is often enough.
Flats with a shared flue
In some blocks of flats the appliances are connected to a shared flue duct that is not suitable for an HR boiler. If that flue cannot be adapted, according to Milieu Centraal a VR boiler, which is less economical, may still be fitted there. Whether your duct is suitable and which appliance may be connected to it is decided by the installer in consultation with the vereniging van eigenaren (VvE, owners' association) or the landlord responsible for the duct.
Option 2: a hybrid heat pump alongside the boiler
A hybrid heat pump works together with a central heating boiler. The heat pump takes over most of the heating and the boiler steps in when it is very cold and for the hot tap water. According to Milieu Centraal, this lets you use around 60 to 70 percent less gas for heating, less in a poorly insulated home. According to Milieu Centraal, the hybrid heat pump is suitable for homes with moderate insulation, and can be connected to the boiler you have now or fitted at the same time as a new boiler. Milieu Centraal even advises: if you opt for a new HR boiler, get a hybrid heat pump straight away.
If your boiler is only a few years old, the heat pump can be placed alongside it and the boiler does not have to go. If the boiler is old, it often makes sense to replace boiler and heat pump in one go, so that they are properly matched and you only have the installer in once. Not every boiler works with every heat pump; have the installer check whether the combination is supported and how the controls work. Also pay attention to the location of the outdoor unit, the noise and the electrics; this is covered in detail in the heat pump guide.
Option 3: fully electric
With a fully electric heat pump, the central heating boiler disappears, and with it, as a rule, the gas for heating and hot water. That requires a reasonably to well insulated home, a heat emission system that works with lower water temperatures and space for an indoor unit with a hot water cylinder. You can test whether that suits you with Milieu Centraal's heating test and a heat loss calculation by the installer. For that, read Having a heat pump installed and, on radiators and underfloor heating, Underfloor heating or radiators: what suits your home and heat source. If your boiler has broken down suddenly and the home is not yet ready for fully electric, a new boiler with a hybrid heat pump is often a realistic intermediate step.
Subsidy: yes for the heat pump, no for the boiler
The Investeringssubsidie duurzame energie en energiebesparing (ISDE, investment subsidy for sustainable energy and energy saving) from RVO (the Netherlands Enterprise Agency) applies to, among other things, a hybrid or fully electric heat pump. The scheme for homeowners is intended for owner-occupiers: you own the home and live in it yourself. An ordinary central heating boiler is not on the list of measures and therefore does not qualify. If you fit a new boiler together with a hybrid heat pump, the subsidy amount depends only on the heat pump, namely on its capacity and energy label; the boiler does not count. Check in advance whether the appliance is on RVO's meldcode list (list of eligible appliances) and read the current conditions on rvo.nl, because they change regularly. You can read which other schemes exist in Sustainable renovation: subsidies and options.
Who is allowed to replace the boiler?
Since 1 April 2023, only a company with a CO-vrij certificate (carbon monoxide certification) may install a central heating boiler, connect it to the flue and commission it (article 6.45 of the Besluit bouwwerken leefomgeving, Bbl, the Dutch Building Decree). That also applies to you as the client: if you have a handyman without a certificate work on the boiler, you are in breach yourself. The reason is carbon monoxide: an incorrectly connected flue or a badly adjusted burner can bring odourless and invisible CO into the house. You can read what you may and may not do yourself with gas in May I install a gas pipe or central heating boiler myself? What the law says.
Check the company in the public register of gas combustion installations of the Toelatingsorganisatie Kwaliteitsborging Bouw (TloKB, the admissions body for quality assurance in construction) and look for the CO-vrij logo on the quote and the company van. If the company also fits a heat pump with an F-gas as refrigerant, separate certificates are required for that. Membership of a trade association such as Techniek Nederland is voluntary and no substitute for the statutory certification. You can read whom to call for which part of the work in Plumber, installer or heating engineer: whom do you call for what.
What the installer checks and does
Replacing a boiler is more than swapping a box. A careful installer looks at the whole installation:
- Flue gas outlet and air supply. Is the existing flue suitable and leak-tight for the new boiler, or does it need replacing? With a shared duct in a block of flats: is the new appliance suitable for it?
- Gas pipe. Is the pipe to the boiler wide enough for the output of the new appliance, especially if you switch to a combi boiler with a higher hot water class? After changes, the pipe should be pressure-tested for leaks.
- Condensate drain. An HR boiler produces condensate that must drain to the sewer via a trap. In a place where it can freeze, that drain must be frost-free.
- Location and space. Does the new boiler fit in the old spot, is there space for a hot water cylinder or a heat pump indoor unit, and does the boiler remain accessible for servicing?
- Commissioning. After fitting, the engineer measures the combustion, adjusts the boiler and records the results. Ask for that commissioning report; it is your proof for the insurer and a future buyer.
- Balancing. Have the system hydraulically balanced, so that each radiator gets the right amount of water and all rooms heat up evenly. That is only possible if every radiator has a balancing valve. In addition, the installer should set the flow temperature, the thermostat and any weather-compensated control correctly.
- Explanation and servicing. Have it explained to you how to check the pressure, top up and bleed the system, and agree who will do the servicing. For modern boilers, according to Milieu Centraal, servicing once every two years is often enough, in consultation with the installer; for older boilers, once a year.
Buying, renting or leasing
Besides buying, some installers and energy companies offer a central heating boiler or heat pump on a rental or lease basis, where you pay a fixed amount per month and servicing and repairs are often included. That spreads the cost, but you do not become the owner and you are often tied in for years. With such a contract, read carefully what happens if you move house, if you cancel early and at the end of the term, and whether you can still apply for a subsidy. Check with RVO whether an ISDE application is possible for a rented or leased appliance. If you rent the home yourself, the boiler is the landlord's responsibility.
What belongs in the quote?
Preferably ask for two or three quotes based on a home visit, and compare whether they contain the same things:
- make, model and output of the boiler, the hot water class and whether it is a combi boiler or a boiler with a hot water cylinder;
- for a hybrid or fully electric heat pump: the type, the meldcode for the ISDE and a calculation of the required capacity;
- what will be adapted to the flue, the gas pipe and the condensate drain;
- the thermostat and the controls: modulating, and if necessary an outdoor sensor;
- whether hydraulic balancing and replacing radiator valves or balancing valves are included;
- removal of the old boiler and finishing the spot;
- the company's CO-vrij certificate and the commissioning report afterwards;
- the guarantee on the appliance and labour, the servicing arrangements and the schedule, including what happens if the old boiler breaks down in the meantime.
You can read how to compare quotes fairly in Comparing quotes: how to read a building quote.
In short: start looking into it when your boiler is around twelve years old, not only when it has broken down. A new HR boiler is simply allowed at the moment, but a hybrid heat pump alongside it saves a lot of gas and qualifies for ISDE, and in a well-insulated home going fully electric may be the better step. Always have the work done by a CO-vrij certified company. On VerbouwPro you post your job free of charge and heating engineers and plumbers from your area respond.