Heating replacement cost in Germany: your share by old system and application date
Whether a replacement turns out cheap or dear depends not only on the quote, but on the old system, the day you apply and who lives in the house.
Worked through by Radif Partners · Editorial policy · How we calculate
Your replacement after the grant
You pay
€18,320
| Grant | €15,680 |
| Eligible | €28,000 |
There is no official average price for replacing a heating system in Germany; the cost is whatever the installer quotes. What is official is how much of it the state covers. For new heating that runs on renewable energy, KfW pays at least 30 % of eligible costs, capped at €28,000 for a single-family house. If you live in the house, you get a 16 % climate speed bonus when the old system runs on oil, coal or night storage, is a gas heater serving one flat, or is a gas or biomass boiler at least 20 years old. The income bonus is added for taxable income up to €50,000. An example: a household with €42,000 income replaces an oil boiler with a heat pump for €34,000 in total. The grant is €15,680, leaving €18,320 to pay. Had it been a gas boiler only 12 years old, the grant would be €11,200. Applying on 1 February 2027, the oil case would get €14,170, and from 1 August 2028 €10,000. A new gas boiler gets no grant at all.
What a replacement costs and what counts
The price of a heating replacement covers more than the unit. Under the guideline of 17 August 2026, eligible items are materials, professional installation, commissioning and the necessary preparatory and finishing work the guideline calls ancillary measures (Umfeldmaßnahmen). They include optimising the distribution system with hydraulic balancing, without which there is no grant, as well as specialist planning and site supervision. The minimum investment is €300. Second-hand units, self-built systems and prototypes are excluded. If you do work yourself, only materials are funded, and only when an installer or an energy efficiency expert confirms the work was done properly.
No official statistic shows what a replacement costs on average. KfW’s own examples range from €20,000 for a split unit in a flat to €41,000 for ground source with solar thermal in a two-family house (product page 458). The figures for a heat pump in detail are under heat pump cost.
The old system matters
For the same €34,000 replacement and the same €42,000 income, the grant depends on what is in the basement today:
| Old system | Rate | Grant | You pay |
|---|---|---|---|
| Oil boiler, any age | 56 % | €15,680 | €18,320 |
| Gas boiler, 24 years | 56 % | €15,680 | €18,320 |
| Gas boiler, 12 years | 40 % | €11,200 | €22,800 |
| Gas heater for one flat, 15 years | 56 % | €15,680 | €18,320 |
| Night storage heaters | 56 % | €15,680 | €18,320 |
| Oil boiler, house let out | 30 % | €8,400 | €25,600 |
The difference lies in the climate speed bonus. It has three conditions that many cost estimates leave out. The old system must be in working order. It must be properly removed and disposed of. And afterwards no fossil or gas-fired heating may supply the home, except fuel cells and hydrogen-ready systems. A pellet boiler instead of the heat pump gets the same rate, €15,680 in the example. With a child under 18, KfW counts income €10,000 lower and the grant rises to €19,600. Remember that income is proven with German tax assessments only, and that both bonuses need the house to be your main residence.
The day you apply
Since the new guideline, two figures fall in fixed steps: the cap for the first home and the climate speed bonus. What counts is the day KfW receives the application, not the day of installation. For the oil boiler example:
| Application from | Cap | Grant | You pay |
|---|---|---|---|
| now (19 October 2026) | €28,000 | €15,680 | €18,320 |
| 1 February 2027 | €27,250 | €14,170 | €19,830 |
| 1 August 2027 | €26,500 | €12,720 | €21,280 |
| 1 February 2028 | €25,750 | €11,330 | €22,670 |
| 1 August 2028 | €25,000 | €10,000 | €24,000 |
Between applying today and applying in August 2028, the example loses €5,680. After approval you have 36 months to install, so an early application does not force a rushed job. The top-up loan can cover your own share:
What the loan has to cover
Left to finance after the grant
€32,120
| Grant | €12,880 |
| Loan at most (eligible costs) | €28,000 |
| Left from your own funds | €4,120 |
| Extra interest discount | yes |
Interest discount up to €90,000 taxable income, for the home you live in only.
Multi-unit houses and letting
In a house with several homes the cap grows: €15,000 for each of the second to sixth, €8,000 each from the seventh. A three-unit house reaches €58,000. The basic grant covers the whole building, the bonuses only the share of the home the owner lives in (information sheet 458). With €60,000 of costs, an owner living in one of the three flats gets €22,427; letting all three, €17,400. More under heating grants for landlords.
Replacing right after buying a house
Many systems are replaced soon after a purchase, and the timing decides about the bonuses. For the bonuses, what counts is the situation on the day of the application: an owner-occupier, in the guideline’s terms, is someone entered in the land register (Grundbuch) as owner who lives in the home as their main or only residence, proven by a land register extract and a registration certificate (Meldebescheinigung). If you apply before you have registered your address there, you get the basic grant only, and KfW says the bonuses can generally not be changed afterwards. The building must be at least 5 years old, counted from the planning application. Income comes from the tax assessments for the second and third year before the application, and income earned abroad counts as well.
When a full replacement is not the plan
Not every old system has to go at once. If you improve the existing one, for example new pumps, a reset heating curve or new radiators, BAFA pays a 15 % grant. It applies to buildings with up to 5 homes and systems older than 2 years; fossil boilers may be at most 20 years old (heating optimisation). If you choose a new gas or oil boiler, you pay the full price and from 2029 must prove a growing share of low-carbon fuel under section 43 of the Building Modernisation Act. The programme as a whole is explained under KfW 458; open questions on the guideline are answered in the FAQ of the ministry, KfW and BAFA.