The fundamental difference between wet (hydronic) and dry (electric) underfloor heating lies in their heat source and distribution method: wet systems circulate heated water through pipes, while dry systems use electric cables or mats to generate heat. Both types offer precise thermostatic control, but they differ significantly in installation, running costs, and how zones or circuits are managed. Wet systems excel in room-by-room zoning, while dry systems offer individual control of each cable circuit, allowing for highly bespoke heating configurations.
Wet Underfloor Heating (Hydronic Systems)
Wet underfloor heating, also known as hydronic underfloor heating, involves circulating warm water through a network of pipes installed beneath the floor. This water is typically heated by a boiler, heat pump, or solar thermal system.
How it Works:
- A manifold distributes heated water from the heat source into a series of loops of piping laid within the floor construction.
- The warm water heats the floor structure, which then radiates heat upwards, warming the room.
- The water eventually returns to the manifold and then to the heat source for reheating.
Key Characteristics:
- Heat Source: Boiler (gas, oil, LPG), air-source heat pump, ground-source heat pump, or solar thermal.
- Installation: More complex and invasive, typically integrated into the floor screed during new builds or major renovations.
- Running Costs: Generally lower for larger areas, especially when connected to efficient heat sources like heat pumps.
- Response Time: Slower to heat up and cool down due to the thermal mass of the water and floor screed, providing a consistent, gentle warmth.
- Zoning: Allows for effective room-by-room zoning, enabling different temperatures in various parts of the home, which enhances comfort and energy efficiency.
- Ideal For: New builds, large extensions, and properties where underfloor heating is the primary heat source.
Dry Underfloor Heating (Electric Systems)
Dry underfloor heating systems utilize electric heating cables or mats installed directly beneath the floor finish. These systems convert electricity into heat, offering a simpler and quicker installation process.
How it Works:
- Electric heating cables, often pre-spaced on a mesh mat, are laid directly onto the subfloor or insulation.
- When electricity passes through the cables, they heat up, radiating warmth through the floor covering into the room.
- Connected to a thermostat, the system maintains the desired floor and room temperature.
Key Characteristics:
- Heat Source: Electricity directly.
- Installation: Simpler and less invasive, often laid directly under tiles, laminate, or engineered wood. Suitable for renovations and individual room projects.
- Running Costs: Can be higher for large areas or if used as the primary heating source due to electricity prices, but efficient for smaller, intermittently used spaces.
- Response Time: Faster to heat up and cool down compared to wet systems, offering quick warmth on demand.
- Control: Offers individual control of each cable circuit, allowing for bespoke heating configurations where specific areas within a room can be heated separately.
- Ideal For: Renovations, conservatories, bathrooms, or as a secondary heating source for warmth and comfort.
Key Differences at a Glance
| Feature | Wet Underfloor Heating (Hydronic) | Dry Underfloor Heating (Electric) |
|---|---|---|
| Heat Source | Heated water via boiler, heat pump, or solar. | Electricity via heating cables/mats. |
| Installation | More complex, pipes embedded in screed. Best for new builds/major renovations. | Simpler, mats/cables laid under floor finish. Ideal for renovations/single rooms. |
| Running Costs | Lower for large areas, especially with efficient heat sources. | Higher for large areas; efficient for small, intermittent use. |
| Response Time | Slower to heat up and cool down (high thermal mass). | Faster to heat up and cool down (low thermal mass). |
| Control | Both types offer thermostatic control. Wet allows room-by-room zoning. | Both types offer thermostatic control. Dry has individual control of each cable circuit, allowing bespoke heating configurations. |
| Floor Height | Typically raises floor height more significantly. | Minimal impact on floor height. |
| Maintenance | Requires occasional boiler/heat pump service. | Generally maintenance-free. |
| Environmental | Can be highly efficient with renewable heat sources. | Depends on the source of electricity; can be eco-friendly if using green energy. |
Choosing the Right System
The choice between wet and dry underfloor heating depends on several factors:
- Project Type: For new builds or extensive renovations, wet systems are often preferred due to their efficiency and lower running costs over large areas. For smaller renovations, single rooms, or spaces where quick installation is key, dry systems are more suitable.
- Budget: Dry systems typically have a lower initial purchase and installation cost. Wet systems have a higher upfront cost but often lower long-term running costs.
- Primary vs. Secondary Heating: If underfloor heating is your primary heating system for the entire home, a wet system is usually more cost-effective in the long run. For supplemental heat or heating specific zones like a bathroom, an electric system might be sufficient.
- Floor Construction: Both systems are compatible with various floor finishes, but wet systems usually require a thicker floor build-up due to the screed.
Ultimately, both wet and dry underfloor heating systems provide comfortable, radiant warmth. Your decision should align with your project's specific requirements, budget, and long-term heating goals. Consulting with a qualified heating engineer can help determine the best solution for your home.
