Heat loads
Room-by-room sizing
Size each zone based on calculated heat loss, including glazing, insulation, orientation and outdoor design conditions.
Hydronic heating
Hydronic Heating Systems
Hydronic heating in Sydney and across NSW, with water-based systems designed around the building, the heat source and the way each space is used.
Water-based heating systems
Underfloor, radiators and towel rails
Heat pump and boiler compatibility
Design, supply and installation across NSW
Hydronic heating overview
What is hydronic heating?
This type of system uses heated water to carry warmth through a building. The water is heated by a central heat source, then distributed to underfloor pipework, radiators, heated towel rails or a combination of these heating methods.
Its strength is that it can be designed around the project rather than treated as a standalone appliance. Floor build-up, room loads, heat source selection, controls and construction timing all shape the final recommendation.
How does hydronic heating work?
Water-Based Heating
Hydronic heating works by moving warm water from a central heat source through a closed pipework network. The heat is released into the room by the selected emitters, commonly underfloor pipework, wall-mounted radiators, heated towel rails or a combination of these.
The system needs to be designed as one connected whole. Heat loads, water temperature, emitter sizing, manifolds, valves, thermostats and plant space all affect how comfortably and efficiently the system operates.
What are the main hydronic heating system types?
System Types
The main hydronic heating options are underfloor heating, radiators and towel rails, supported by a heat source such as an air-to-water heat pump or boiler. Underfloor systems suit projects where radiant warmth can be built into the floor, while radiators and towel rails can suit rooms where floor heating is not practical.
In-slab underfloor heating is planned before a new concrete slab is poured. In-screed systems sit above the structural slab and closer to the finished floor, which can suit renovations, tiled areas or projects needing a more responsive floor system.
For underfloor heating, insulation boards can be installed above the structural slab before the pipework and screed are laid. This helps reduce downward heat loss, allowing the floor to warm more efficiently and improving heat retention. Where suitable for the project, insulation can support faster response times and lower overall heating demand.
What are the main benefits and considerations?
Comfort & Design
Hydronic heating provides quiet, even warmth without relying on forced airflow. A single system can combine underfloor heating, radiators and towel rails, while zoning allows different areas to operate according to occupancy and comfort needs.
The system should be planned around the building from an early stage. Floor construction, insulation, available wall space, plant location and the selected heat source all influence which hydronic option will suit the project.
Hydronic systems
Compare hydronic systems by floor construction and project stage.
Start with the system type, then move into the detail page that best matches the project stage and construction method.
01
Hydronic Underfloor Heating
Concealed radiant floor heating for new builds, renovations and projects where comfort should come through the floor.
02
Hydronic Underfloor Heating In-Slab
Pipework embedded into a new concrete slab for steady background radiant heating and strong thermal mass.
03
Hydronic Underfloor Heating In-Screed
Pipework installed above the structural slab within a screed layer for a more responsive radiant floor system.
Design considerations
Hydronic heating is a complete system, not a single product.
Heat emitters, heat source, pipework, controls and water temperatures must be engineered as one system.
Heat source
Temperature and capacity matching
Match heat pumps or boilers to the building load, flow temperature and required emitter output.
Hydraulics
Flow and pipe sizing
Coordinate pipe sizes, circuit lengths, manifolds and pumps to maintain design flow rates.
Controls
Zoning and temperature control
Coordinate thermostats, actuators, valves and weather compensation for stable, efficient zoning.
Construction
Build-up and sequencing
Plan pipe layouts, floor build-ups and trade sequencing before in-slab, in-screed or radiator installation.
Commissioning
Testing and balancing
Pressure test, flush and balance the system, then verify controls, zones and heat-source operation.
System choices
Choose the heating system and heat source together.
| System type | Best suited to | Planning notes |
|---|---|---|
| Hydronic underfloor heating | New homes, major renovations and projects wanting concealed whole-floor radiant warmth. | Choose in-slab for new concrete slabs, or in-screed where heating sits above the structural slab. |
| Panel radiators & towel rails | Renovations, bedrooms, bathrooms and rooms where underfloor heating is not practical. | Panel radiator sizing, available wall space, bathroom layout and system water temperature should be coordinated early. |
| Hydronic heat pumps | Projects seeking efficient all-electric heat generation for underfloor systems or radiators. | Flow temperature, buffer tanks, controls and heat loads should be matched to the building. |
Related system decisions
Plan the supporting parts of the system.
These related elements help shape the final system specification and are useful next steps during design.
FAQ
Common questions.
Is hydronic heating expensive to run?
Running cost depends on the building heat load, insulation, zoning, water temperature and heat source. A system designed around suitable water temperatures and controls can operate efficiently, especially when paired with a correctly selected hydronic heat pump.
Can hydronic heating be installed in an existing home?
It depends on the building and available construction depth. When installing hydronic heating in an existing home, floor build-up, pipe routes, wall space and plant location should be reviewed first. Radiators, towel rails and some in-screed systems may suit renovations, while in-slab heating is generally planned for new concrete slabs.
Can hydronic heating be zoned?
Yes. Thermostats, manifolds, valves and controls can help different rooms or areas operate separately, so lightly used spaces do not need to be heated the same way as primary living areas.
Should I choose a heat pump or boiler?
That depends on the heat load, required water temperature, emitter sizing, available power, plant space and project goals. Air-to-water heat pumps can be a strong all-electric source when the full hydronic system is designed around them.
How quickly does hydronic heating warm up?
Response time depends on the emitter and floor construction. In-slab systems provide steadier background heat through thermal mass, while in-screed systems, radiators and towel rails can respond more quickly when sized and controlled correctly.
Projects
Projects using hydronic heating systems
Hydronic in-screed underfloor heating installed over 10mm Profi Duo boards across a South Bowenfels residence.
South Bowenfels, Central Tablelands, NSW
10mm Profi Duo Board Hydronic Underfloor Heating – South Bowenfels
Hydronic Underfloor Heating - In-Screed
A multi-zone hydronic underfloor heating system installed at a Bar Beach residence.
Bar Beach, Newcastle, NSW
Hydronic Heating System – Bar Beach
Hydronic Underfloor Heating - In-Screed
Hydronic in-screed underfloor heating using 10mm pipe installed across multiple zones of a Bronte residence.
Bronte, Eastern Suburbs, NSW
Hydronic In-Screed Underfloor Heating – Bronte
Hydronic Underfloor Heating - In-Screed
Start with the system
Plan the heating system around the whole building.
Share your drawings and project stage. SmartHeat can compare emitters, heat sources and controls for the proposed building.
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Design, Supply & Installation