Underfloor heating manifolds, flow balancing & multi-zone controls
The manifold is the stainless-steel distribution hub of a wet underfloor heating system.
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How many manifold ports does your floor need?
| Manifold size | Floor area covered (16mm pipe @ 150mm) | Floor area covered (12mm overlay @ 125mm) | Typical trade hardware cost (incl. VAT) |
|---|---|---|---|
| 2-Port Manifold | Up to 28 m² (1–2 rooms) | Up to 16 m² (1 room) | €155–€185 |
| 4-Port Manifold | 30 m² – 55 m² (extension / 2–3 rooms) | 18 m² – 32 m² (kitchen extension) | €200–€235 |
| 6-Port Manifold | 55 m² – 85 m² (medium ground floor) | 32 m² – 48 m² (2–3 rooms) | €240–€280 |
| 8-Port Manifold | 85 m² – 115 m² (3-bed semi ground floor) | 48 m² – 65 m² (ground floor) | €285–€330 |
| 10-Port Manifold | 115 m² – 145 m² (4-bed detached floor) | 65 m² – 80 m² | €330–€375 |
| 12-Port Manifold | 145 m² – 175 m² (large open-plan floor) | 80 m² – 96 m² | €375–€425 |
Rule of thumb: with 16mm pipe at 150mm centres, each loop should never exceed 100 linear metres (covering roughly 14 to 15 m² of floor). That means a 45 m² open-plan kitchen/dining/living room is divided into 3 separate pipe loops occupying 3 manifold ports, all linked to a single room thermostat.
How sight-glass flow meters (L/min) are balanced
Water always takes the path of least resistance. If a manifold has a short 35m utility-room loop right beside three 95m kitchen-living loops and all ports are left wide open, hot water will race through the short utility loop and return to the heat source before the living room warms up.
During commissioning, the installer calculates the required flow rate in litres per minute for every loop using its design heat load (W) and a 5°C–7°C Delta-T: Flow (L/min) = Loop Output (W) ÷ (4186 × ΔT × 60). By twisting the transparent sight-glass collar on the top flow bar while the circulation pump runs, a 35m loop is throttled to ~1.1 L/min while a 95m loop is opened to ~2.6 L/min so every room heats at the exact same speed.
Best place to position the manifold cabinet
- Central utility room, under-stairs press or pantry: Mounting the manifold centrally keeps radial supply-and-return tails short so you do not waste pipe length travelling down long corridors.
- Height & access clearance: The bottom manifold rail should sit 300mm to 450mm above finished floor level so 16mm pipes bend up smoothly through 90° conduit bends without kinking, with a clear front door for bleeding air vents and checking sight glasses.
- Conduit sleeving through doorways: Wherever multiple flow/return tails leave the manifold cupboard together, every second pipe is sleeved in flexible corrugated conduit so the narrow doorway screed does not overheat above 29°C.
Get your underfloor heating priced in 4 quick taps
Tell us about your floor and heat source. Your request goes to one vetted underfloor heating installer covering your county, who rings you back to discuss pipe spacing, manifold zones and screed depth before giving a written quote.
Underfloor heating installation guides & specifications
Detailed Irish engineering & cost guides covering pipe spacing, manifold balancing, 15mm retrofit overlays, 35°C heat pump commissioning and floor coverings.
More technical resources: Liquid screed for underfloor heating · All guides & calculator hub · Technical trade glossary (A–Z) · Frequently asked questions · All 26 counties covered
Manifolds & zones: common questions
Why is one room cold when the rest of my underfloor heating is warm?
In 9 out of 10 cases, a single cold room is caused by one of three simple manifold checks: (1) the 230V thermal actuator on that port has failed closed (unclip it to see if the pin pops up), (2) the metal pin beneath the actuator has stuck down after summer and needs gently freeing, or (3) an airlock is trapped in that loop and needs flushing through the manifold drain cock.
How many thermostats do I need for a 6-port manifold?
You need one thermostat per room (zone), not one per manifold port. If a 6-port manifold has 3 loops in an open-plan kitchen-living room, 1 loop in the sitting room, 1 in the hall and 1 in the downstairs bathroom, you have 4 zones (4 thermostats). The 3 kitchen actuators are wired in parallel to the single kitchen thermostat terminal in the wiring centre.
Do smart thermostats like Heatmiser Neo, Salus or Nest work with underfloor heating?
Yes — multi-zone systems typically use dedicated underfloor heating smart hubs (such as Heatmiser NeoStat, Salus Quantum or Drayton Wiser) that support wired or wireless 230V wiring centres AND accept plug-in remote floor temperature probes for bathrooms and timber floors.
Underfloor heating installation across all 26 counties
Every quote request is routed to one vetted underfloor heating installer covering your county — from Dublin, Cork, Galway and Limerick to Kildare, Meath, Wicklow, Wexford, Louth, Kerry, Clare, Waterford and Donegal. Pick your county for local housing, heating and radon figures. View full 26-county directory →
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