ASHP related, Underfloor Heating General
🏡 Using an Air Source Heat Pump with Underfloor Heating: How Much Heat Output Can You Expect?
Apr
🏡 Using an Air Source Heat Pump with Underfloor Heating: How Much Heat Output Can You Expect?
Air source heat pumps (ASHPs) are becoming a go-to solution for low-carbon heating, especially when paired with underfloor heating (UFH). If you’re planning a setup with 16mm underfloor pipes and a fl
ow temperature of 45°C, you might be wondering: how much
heat output per square meter can I actually expect?
Let’s break it down in simple terms.
🌡️ What Determines Heat Output?
When using underfloor heating with an ASHP, the heat output (measured in watts per square meter, or W/m²) depends on a few key factors:
Flow and return temperatures – These affect the average water temperature.
Pipe spacing – The closer the pipes, the more even and higher the heat output.
Floor construction – Screed depth, insulation, and surface materials (like tile, wood, or carpet) all impact performance.
Room temperature – The bigger the difference between the floor and the room, the more heat is transferred.
🔧 A Typical Setup: The Numbers
Let’s assume a fairly standard UFH installation with the following specs:
Pipe size: 16mm (common for UFH)
Flow temperature: 45°C
Return temperature: 35°C (typical for ASHP setups)
Pipe spacing: 150mm
Floor surface temperature: Around 27–29°C
Room temperature: 20°C
This gives us an average water temperature of 40°C, and a temperature difference (ΔT) betwee
n the floor and the room of roughly 7–8°C.
👉 Estimated heat output: 70–90 W/m²
This is usually sufficient for well-insulated homes built to modern standards, especially in living spaces and bedrooms.
💡 A Few Quick Examples
| Avg Water Temp | Room Temp | ΔT | Estimated Output |
|---|---|---|---|
| 40°C | 20°C | 7–8K | 70–90 W/m² |
| 35°C | 20°C | 5–6K | 50–70 W/m² |
| 30°C | 20°C | ~5K | 30–50 W/m² |
The lower the flow temperature, the less heat you’ll get—but the more efficient your heat pump becomes. It’s all about finding the sweet spot between comfort and efficiency.
🧰 Pro Tips for Better Efficiency
Insulate properly – Floors, walls, and especially under the screed.
Use tight pipe spacing in high-demand areas (like 100mm in bathrooms).
Choose the right floor finish – Tiles and stone transfer heat better than carpet or thick wood.
Zone your system – Independent control for rooms improves comfort and efficiency.
✅ So, Is 45°C Good for Underfloor Heating?
Yes! A 45°C flow temperature is ideal for combining an ASHP with underfloor heating. It provides good heat output without overworking the heat pump, maintaining excellent system efficiency.
If your home is well insulated, you might even get away with lower temperatures, which means even more savings and a greener footprint.
📦 Wrapping Up
Underfloor heating paired with an air source heat pump offers a low-energy, comfortable heating solution. With a 16mm pipe and 45°C flow temp, expect around 70–90 W/m², enough to keep your space cozy while keeping running costs down.
Want to get the best out of your setup? Focus on insulation, pipe layout, and smart temperature control—and your ASHP + UFH system will serve you well for years to come.
