Underfloor Heating Installation Guide

1. Pipe Laying

Layout Patterns

Key Rules

• Max loop length: 100m (16mm), 120m (17mm), 80m (12mm)
• Min bend radius: 5×OD (80mm for 16mm, 85mm for 17mm)
• Clip spacing: 300mm (PEX), 600–800mm (Alu-PEX), 200mm on bends
• Expansion joints: every 30m² or 6m max dimension — pipe conduit required
• Doorways: conduit sleeve, pipe not in screed across threshold
• Manifold tails: minimum 300mm free pipe for connection

Fixings by Floor Type

2. Manifold Connection

Pipe Preparation

1. Cut pipe square with pipe cutters (not hacksaw)
2. Remove burrs internally and externally
3. Check pipe ovality — reject if >0.5mm
4. Mark insertion depth on pipe (fitting depth + 2mm)

Fitting Types

• Eurokonus (3/4″): Compression, reusable, 16×2mm & 17×2mm
• Soft-Seal (1″): O-ring seal, push-fit, 16×2mm only
• Press-Fit (16/20mm): Permanent, requires press tool, Alu-PEX compatible

Labelling

Label BOTH ends of every loop: zone number, room name, loop length. Use cable ties with printed tags or permanent marker on heat-shrink.

3. Pressure Testing

Procedure

1. Close all manifold flow/return valves
2. Connect test pump to manifold fill/drain valve
3. Pressurise to 1.5× design pressure (min 6 bar, max 10 bar)
4. Hold for 30 minutes — no visible pressure drop
5. Inspect every joint, fitting, manifold connection
6. Record: date, time, pressure, duration, tester name, witness
7. Photo every manifold, every joint cluster
8. Leave system pressurised until screed poured (min 24hr)

Test Certificate Must Include

• Project address & plot number
• System type (screed/timber/overlay)
• Pipe type & size
• Test pressure & duration
• Pass/Fail + any remedial actions
• Installer signature + company stamp

4. Commissioning

Flushing & Filling

1. Remove all actuator heads (if fitted)
2. Open all flow & return valves
3. Connect mains to fill valve, hose from drain valve to waste
4. Flush each loop individually — min 2 minutes clear water
5. Fill system slowly — vent air at manifold air vents
6. Check pressure: 1.5–2.0 bar cold

Air Removal

Run pump at max speed. Open air vents until water flows steadily. Repeat daily for 3 days. Automatic air vents: check weekly.

5. Balancing

Flow Meter Method (Combimix/Standard with flow meters)

1. Calculate target flow per loop: Q = (Heat load × 0.86) / ΔT (litres/hour)
2. Set all flow meters to calculated values
3. Run system 30 mins, verify return temps within 2°C of design
4. Fine-tune: reduce flow on hot loops, increase on cold
5. Record final flow meter readings

Temperature Method (No flow meters)

1. Run system to steady state (1+ hours)
2. Measure flow & return temp at manifold per loop
3. Target ΔT: 5–10°C (heat pump), 10–15°C (boiler)
4. Adjust return valves: close on low ΔT, open on high ΔT
5. Iterate until all loops within 1–2°C of target

6. Startup & Screed Drying

Gradual Warm-Up Protocol (BS EN 1264 / CIBSE)

Critical Rules

• Do NOT exceed 35°C flow for first 28 days (screed curing)
• Do NOT force-dry with high temps — causes cracking
• Keep rooms ventilated — moisture must escape
• Record daily flow/return temps for warranty

Client Handover Checklist

• As-built drawings (pipe layouts, manifold schedules)
• Commissioning & balancing records
• Pressure test certificate
• Thermostat programming guide
• Maintenance schedule (annual: air vents, inhibitor check, pump)
• Warranty registration