A heat pump is chosen by water temperature, not by floor area.

Underfloor heating runs at 35 °C, existing radiators need 55 °C. That one number decides the configuration, its efficiency and the work involved. Answer four questions and we'll name it.

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Leaving water temperature — where our data actually exists

Setting range 20–80 °C · declared performance at 35 and 55 °C

20 °CLower limit of the setting range
35 °CUnderfloor heating
COP up to 5.50 at A7/W35 · SCOP up to 5.20 at 35 °C
55 °CExisting radiators
COP 3.05–3.40 at A7/W55 · SCOP up to 3.85 at 55 °C
80 °CUpper limit of the setting range — not a performance point
No performance is declared above 55 °C

Declared performance data

Setting range only — ask before you design around it

  • 4 – 35.3 kW

    Across the range: 4–16 kW monoblock, 6.5–24 kW split, up to 35.3 kW for pools

  • A+++

    Seasonal space heating class for the Hamme monoblock line, average climate — declared at both 35 and 55 °C leaving water. Split units are A++ at 55 °C

  • R290 · natural refrigerant

    Natural refrigerant in the Hamme monoblock line. Split and pool units use R32

  • −25 °C

    Declared heating operating range to −25 °C. Output falls as it gets colder — confirm capacity at your design temperature

Figures declared at A7/W35 (air 7 °C, leaving water 35 °C) and A7/W55.

Situations

Find the one that sounds like your house

Every situation below maps to a configuration we can name today, for Germany. The last card is the one where a heat pump is the wrong answer — we'd rather you knew now.

Germany

Replacing a gas or oil boiler, keeping the radiators

The house is from the eighties or nineties, the radiators are fine, and you have no intention of lifting the floors.

Fits
Monoblock, or outdoor unit with hydrobox, running at 55 °C. Dual-zone control if some rooms already have underfloor.
Accept
Around 3.05–3.40 COP at 55 °C instead of 5.50 at 35 °C. If a radiator can only heat its room at 70 °C, we declare no data up there — that room needs a bigger radiator, or the boiler stays as backup.

Hamme monoblock · Hamme Hydro + Hydrobox

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Germany

Night-storage electric heating

Storage heaters, an expensive night tariff, and no water pipework anywhere in the house.

Fits
Any configuration — but this is a full wet system installed from scratch, so treat it as new build rather than a swap.
Accept
The heat pump is the smaller half of this project. Pipework and emitters are the rest of it.

Hamme All-in-One · Hamme monoblock

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Germany

Keep the boiler for the coldest days

Full replacement doesn't fit the budget, or the radiators need more than 55 °C on the worst nights.

Fits
A smaller heat pump for the base load with the boiler on peaks. The control box drives the auxiliary heat source directly.
Accept
Two systems to service, and the boiler still needs its fuel supply.

Hamme + Control Box

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Germany

Underfloor heating throughout

New build, or a renovation deep enough that the floors are coming up anyway.

Fits
Any configuration at 35 °C — where the equipment does its best work: COP up to 5.50 at A7/W35 and SCOP up to 5.20 at 35 °C.
Accept
Underfloor is slow to respond. Room-by-room control matters more than it does with radiators.

Hamme All-in-One · Hamme monoblock

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Germany

Underfloor downstairs, radiators upstairs

A half-renovated house where the two floors want two different water temperatures.

Fits
Dual-zone control runs both circuits at their own design temperature from one machine.
Accept
The radiator zone sets the efficiency ceiling for the hours it is calling for heat.

Hamme + Control Box · All-in-One

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Germany

No plant room to put anything in

No garage, no utility room, nowhere to stand a cylinder next to a hydraulic module.

Fits
All-in-One: cylinder, backup heater and expansion vessel in one indoor tower.
Accept
It is 1780 mm tall, or 1985 mm with the 240 L tank, and 115–121 kg before it holds any water. Measure the door and the ceiling first.

Hamme All-in-One 200 / 240 L

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Germany

You already have a good hot-water cylinder

The cylinder was replaced recently and there is no reason to throw it away.

Fits
Outdoor unit plus hydrobox — a compact wall module with the 3-way valve and backup heater.
Accept
BAUF does not sell a standalone cylinder, and the hydrobox has no expansion vessel. Both come from your installer.

Hamme Hydro + Hamme Hydrobox

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Germany

More than 16 kW of heat needed

A large or poorly insulated house where one residential unit won't cover the load.

Fits
Sauer split reaches 23.98 kW in a single system; alternatively up to eight units cascade over Modbus through the control box.
Accept
Sauer runs on R32 and tops out at 60 °C flow. Cascade means more outdoor units and more places to put them.

Sauer R32 · Hamme + Control Box

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Germany

The outdoor unit has to go a long way from the plant room

The only sensible place for the outdoor unit is at the other end of the property.

Fits
Split: the refrigerant line runs outside and only the hydraulic module sits indoors.
Accept
Refrigerant work on site, R32 instead of R290, and 60 °C maximum flow — which rules out the hottest radiator systems.

Sauer R32

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Limits

When we'd tell you not to

Three situations where the answer is no, or not yet.

Nowhere outside to put the unit — an apartment or a protected facade leaves no compliant position for an R290 monoblock. A neighbour a few metres from the only mounting position, where 55–66 dB(A) of sound power at night is a real problem. Not enough electrical supply — a 16 kW single-phase unit draws up to 34.8 A, and there is no three-phase version below 10 kW.

Talk to us before spending anything

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None of these is quite your house?

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The decisions behind the choice

Four forks. Everything else is detail.

Monoblock or split?

Hamme monoblock heat pump mounted on wall brackets on the outside of a house
Hamme monoblock — hydraulics and expansion vessel sealed inside the outdoor unit.

Monoblock — Hamme, R290

Everything refrigerant-related is sealed in the outdoor unit, so no refrigerant circuit has to be connected on site. Expansion vessel already inside (4.5 L up to 10 kW, 8 L above), water up to the full 20–80 °C setting range. 4–16 kW.

Sauer split heat pump outdoor compressor unit standing beside a house
Sauer split — the outdoor half. The hydraulic unit goes indoors, connected by a refrigerant line.

Split — Sauer, R32

Indoor hydraulic unit, outdoor compressor unit, refrigerant line between them. Reaches 23.98 kW without cascading and suits long distances to the plant room. Water tops out at 60 °C, and the refrigerant is R32, not R290.

The trade: Monoblock keeps the installation simpler and the refrigerant natural; split buys you distance and capacity, at 60 °C maximum flow.

All-in-One, or outdoor unit plus hydrobox?

All-in-One indoor tower standing in a utility room beside a doorway
All-in-One — 1780 mm (1985 mm for 240 L), 115–121 kg empty. Measure the doorway.

All-in-One — tank built in

200 or 240 L cylinder, 3 kW immersion heater, 1+2 or 2+4 kW backup heater and an 8 L expansion vessel in one indoor tower. One supplier, one delivery. It stands 1780 mm tall (1985 mm for the 240 L version) and weighs 115–121 kg empty — measure the doorway.

Wall-mounted hydrobox module next to an existing hot water cylinder in a utility room
Hydrobox — wall module plus the cylinder you already own.

Outdoor unit + Hydrobox

A compact wall module with a 3-way valve and backup heater, connected to your own cylinder. The right answer when a good cylinder is already installed. Two things are on you: the expansion vessel, and the cylinder itself — BAUF does not sell a standalone tank.

The trade: All-in-One removes decisions and suppliers; the hydrobox route keeps a cylinder you already own and costs you two components BAUF won't be supplying.

Replace the boiler, or keep it for the coldest days?

Full replacement

The heat pump covers the whole load. One heating system instead of two. It needs the emitters to work at 55 °C or below, and it needs the electrical supply to carry the largest unit you might need.

Bivalent

The heat pump carries the base load, the existing boiler takes the peaks. The control box integrates an auxiliary heat source directly. Lower electrical demand, smaller unit, and a fallback on the worst night of the year — but you keep two systems and two service visits.

The trade: If your radiators need more than 55 °C, bivalent is not a compromise — it is the honest answer, because we declare no performance above 55 °C.

Underfloor heating, or the radiators you already have?

Underfloor — 35 °C

Where a heat pump does its best work: COP up to 5.50 at A7/W35 and a seasonal SCOP up to 5.20 at 35 °C. If you're building or stripping floors anyway, this is the version worth designing for.

Existing radiators — 55 °C

Still works, and no floors come up. COP around 3.05–3.40 at A7/W55 — roughly a third less heat per unit of electricity than underfloor. Oversized radiators or a couple of replacements close much of that gap.

The trade: Mixed emitters don't force a choice — dual-zone control runs two circuits at two different temperatures from one machine.

Still deciding between two of these?

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The range

Every product, one line each

ProductWhat it isOutputRefrigerant
Hamme
HammeMonoblock with hydraulics and expansion vessel on board. No backup heater.Output4–16 kWRefrigerantR290
Hamme Hydro
Hamme HydroThe same outdoor unit prepared for a separate indoor module.Output4–16 kWRefrigerantR290
Hamme Hydrobox
Hamme HydroboxIndoor module with 3-way valve and 3 / 6 kW backup heater. Needs your cylinder.Outputto 10 / to 16 kWRefrigerant—
Hamme Hydro All-in-One
Hamme Hydro All-in-OneIndoor tower with a 160, 200 or 240 L cylinder and a built-in backup heater.Output10 / 16 kWRefrigerant—
Hamme Control Box
Hamme Control BoxCascade of up to 8 units over Modbus, dual-zone, bivalent boiler, pool, solar thermal, scheduling.Output—Refrigerant—
Sauer R32
Sauer R32Split system: indoor hydraulic unit plus outdoor unit. Water to 60 °C.Output6.46–23.98 kWRefrigerantR32

Full specifications, drawings and manuals live in the catalogue.

Open the catalogue
Budget

We don't publish prices. Here's what moves them.

BAUF sells through installers and distributors, and they price the whole job, not the box. These are the six lines that decide what you'll be quoted.

The unit

Capacity class and configuration. All-in-One costs more than a bare monoblock and saves you buying a cylinder.

Hydraulics

Buffer tank if the system volume is low, expansion vessel on hydrobox installs, safety group, filter, glycol.

Hot water

A cylinder, unless it's built in or you already own one.

Electrical

Breaker, RCD, cable run. A 16 kW single-phase unit draws up to 34.8 A — sometimes the supply itself has to be upgraded.

Emitters

Nothing, if the radiators cope at 55 °C. A few replaced radiators, if they don't.

Installation

Mounting, drainage, pipework, commissioning. Installation must comply with local regulations and be carried out by a suitably qualified installer.

Heat pump plant room with buffer tank, cylinder, manifold, safety group and electrical connections
Most of a quote is what surrounds the unit — hydraulics, cylinder, electrical work, labour.

Only a seller can quote the whole job. We can tell you which one to ask.

Find a sellerAsk on WhatsApp
Behind the product

What we can show you

January 2026

European hub in Lisbon

Showroom, training centre and warehouse under one roof — spare parts held in Europe and installers trained on the equipment they fit.

Heat pumps and air conditioners on display in the BAUF showroom in Lisbon
The showroom at the Lisbon hub.
Warranty

5 years on the unit, 7 on the compressor

As published in the 2026 catalogue for the monoblock range. Terms may vary by market.

The compressor of a BAUF heat pump
The compressor — the part the seven-year term is written for.
March 2026

MCE, Milan

Shown at Mostra Convegno Expocomfort, after C&R Madrid in 2025.

BAUF stand at Mostra Convegno Expocomfort in Milan
MCE Milan, March 2026 — the stand on the show floor.
Channel

Professionals only

BAUF sells through installers and distributors and controls distribution, training and service. We don't sell direct — the finder ends with a seller near you.

A BAUF specialist explaining the equipment to visiting installers at an exhibition stand
C&R Madrid, 2025 — talking to the people who fit the equipment.
Before you ask us

The questions people actually have

Sound power across the monoblock range is 55–66 dB(A) and sound pressure 44–55 dB(A), rising with capacity. A 4 kW unit is at the quiet end, a 16 kW unit is not. Siting matters more than the number: distance to the boundary, what the sound reflects off, and whether the bedroom window faces it. There's a silent mode; we don't publish how many decibels it saves, so ask your installer to model the actual position rather than trusting a single figure.

It runs. Declared heating operation goes down to −25 °C. But output falls as the air gets colder, and the figures on this page are declared at +7 °C air. That's the single most important sentence here: the capacity you need on the coldest night is not the capacity in the brochure, which is exactly why a heat-loss calculation isn't optional.

We won't give you a number, because an honest one needs your tariff, your heat demand and your flow temperature — and a dishonest one is easy to write. What we can give you is the physics: at 35 °C flow the seasonal figure reaches 5.20, at 55 °C it's around 3.85. Your installer can turn that into euros once the heat loss is known.

Five years on the unit, seven on the compressor, as published for the monoblock range in the 2026 catalogue. Spare parts are held at the Lisbon hub rather than shipped from Asia per order. Service goes through the installer who fitted it.

Sometimes. It depends on the water volume in your system and how much of it stays open when thermostats close — a small underfloor loop behind closed zone valves will make any inverter cycle. It's a question for the installation manual and the installer, not for a web page.

We don't publish a figure, and any brand that gives you one hasn't seen your house. What changes it: whether the pipework is already there, whether the cylinder is being replaced, and whether the electrical supply needs work.

No. Wi-Fi and Modbus are there for remote control and building management, and there's a smart-grid function. The heating works from the controller regardless.

Asked something we haven't answered here?

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Configuration finder

Four questions

You'll get a configuration, a capacity class and the efficiency figure that matches your emitters. Not a quote, and not an engineering design.

Step 1 of 4

What are you heating?

Pick the closest one.

Prefer to talk about price first?Find a seller
Where to buy

We sell through people who install

Find a seller or distributor

Pick your country and see the partners listed for it.

Still not sure which one is yours?

Send us the room count and what you're heating with now. That's usually enough for a first answer.

Ask on WhatsApp

Monday to Friday, 09:00–18:00

Brusseler Strasse 1-3, 60327 Frankfurt am Main, Germany

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