Short answer: You need one manifold port for every heating loop, and every loop has its own flow and return. Count loops by dividing each room's pipe (area × pipe per m², plus tails) by 100m for 16mm pipe or 80m for 12mm, rounding up per room. As a guide, plan one 16mm loop per 12 to 14m² at 150mm centres. MaxHeatUFH manifolds go up to 12 ports, so larger floors use two manifolds.
The port count sets the manifold size, the number of actuators, Eurocone connectors and the wiring centre. Get it wrong and you either run out of ports or pay for ports you never use. This guide shows how to count loops, how loops relate to zones and thermostats, and what each port costs to kit out.
How many ports does a UFH manifold need?
A manifold needs exactly one port per loop. Each port has a flow outlet on the top bar and a return on the bottom bar, so a "6 port" manifold serves 6 loops, not 3.
Ports are about loops, not rooms. A small WC may have one loop. A 36m² kitchen-diner may need three. A loop should not pass through a wall into another room, so each room gets at least one loop of its own.
How do I count the loops?
Work room by room: heated area × pipe per m², add the tails, divide by the loop limit and round up.
- Heated area. Measure each room and take off fixed units, baths, showers and WCs.
- Floor pipe. Multiply by 10m/m² at 100mm centres, 6.7m/m² at 150mm, or 5m/m² at 200mm.
- Tails. Add twice the distance from the room to the manifold for each loop.
- Divide. Divide by 100m for 16mm pipe or 80m for 12mm, and round up.
- Add up. The total across all rooms is your port count.
The 100m (16mm) and 80m (12mm) figures match the maximum circuit lengths in maker installation guides. Our guide to how much underfloor heating pipe you need shows the pipe sums in full.
| Heated area | Loops at 150mm | Loops at 100mm |
|---|---|---|
| 10m² | 1 | 2 |
| 15m² | 2 | 2 |
| 20m² | 2 | 3 |
| 30m² | 3 | 4 |
| 40m² | 3 | 5 |
| 50m² | 4 | 6 |
This table assumes 16mm pipe and the manifold 4m from the room (8m of tails per loop). Longer tails use up loop length, so a room far from the manifold may need one more loop.
Worked example: an 8 port ground floor
A 72m² heated ground floor at 150mm centres in 16mm pipe needs 8 ports: 3 for the kitchen-diner, 2 for the lounge, and 1 each for the hall, utility and WC.
- Kitchen-diner, 36m²: 240m floor pipe, so 3 loops of 92m with 6m tails.
- Lounge, 18m²: 120m floor pipe, so 2 loops of 76m with 8m tails.
- Hall 9m² (64m), utility 6m² (46m) and WC 3m² (28m): 1 loop each.
The loops range from 28m to 92m. The short WC loop will take far more flow than the long kitchen loops unless you balance the manifold, which is why loop lengths should be as even as the rooms allow.
What is the difference between a loop, a port and a zone?
A loop is one length of pipe, a port is where it connects, and a zone is an area controlled by one thermostat. One zone can have several loops.
In the example above, the kitchen-diner is one zone with three loops. Its thermostat opens three actuators together through the wiring centre. So that floor has 8 ports but only 5 zones and 5 thermostats.
- Actuators: one per port, so 8.
- Thermostats: one per room or zone, so 5.
- Wiring centre: sized to the number of thermostats. A Heatmiser UH4 takes up to 4 zones, a UH8 up to 8.
With a heat pump, fewer, larger zones often work better at low flow temperatures, for example one thermostat per floor. The port count stays the same, because it depends on loops, not thermostats. See zoning, thermostats and wiring centres for how this is wired.
What does each port cost to kit out?
Each port needs one thermal actuator, two Eurocone connector cores and, as standard in our kits, two pipe support bends. That adds about £16.28 per port on top of the manifold.
| Item per port | Qty | Cost |
|---|---|---|
| 2-wire thermal actuator 230V | 1 | £12 |
| Eurocone connector core | 2 | £2.84 |
| Pipe support bend | 2 | £1.44 |
Prices inc VAT, October 2026. Each manifold also needs a 1" ball valve set (from £22), and in our standard kits a 22mm 2-port zone valve (£57), plus a pump and blending or non-mixing pack to suit the heat source.
Which manifold size should I buy?
Buy the port count your loops need. MaxHeatUFH stainless steel manifolds come in every size from 2 to 12 ports.
| Ports | Dualmix | Auto-balancing |
|---|---|---|
| 4 | £77 | £89 |
| 6 | £105 | £129 |
| 8 | £133 | £166 |
| 10 | £159 | £201 |
| 12 | £197 | £246 |
Prices inc VAT, October 2026. The Dualmix comes assembled with a pressure gauge and automatic air vent. The auto-balancing manifold has pressure-independent return valves and a flow meter on every circuit reading 0 to 4 L/min, so each loop holds its set flow as other zones open and close. That makes it a good fit for heat pumps and for floors with uneven loop lengths.
If you might add a room later, the Dualmix can take a 1 port extension (£25). Unused ports can also be capped off.
When do I need more than one manifold?
Use a second manifold when you need more than 12 loops, or when one manifold would leave tails so long they use up most of each loop.
- More than 12 loops: split the floor between two manifolds. Keep each room's loops on the same manifold where you can.
- Two floors: most homes with UFH upstairs and downstairs use one manifold per floor.
- Long, spread-out floors: if a room is 15m from the manifold, 30m of a 100m loop is tails. A second manifold nearer that end of the house often saves pipe and gives better heat.
- Crossing tails: tails should never cross other loops on the way back. If they would, connect that loop to the other manifold.
Where should the manifold go?
Put the manifold as near the middle of the area it serves as you can, on an internal wall, with space for the pump pack beside it. A central manifold keeps tails short and loops even.
Good spots are a hall cupboard, under the stairs or a utility room. Where many tails converge, the floor near the manifold can run warm, so sleeve tails in pipe conduit where they pass through areas that are already heated by their own loop. Allow room to reach every port for balancing and actuator changes. Our guide to balancing UFH loops covers setting the flows.
Products for this job
- Dualmix Stainless Steel Manifold (2 to 12 Port)
- Auto-Balancing Stainless Steel UFH Manifold
- 2-Wire Thermal Actuator 230V
- Eurocone Connector Cores 3/4"
- Manifold Ball Valve Set 1"
- Heatmiser UH8 8 Zone Wiring Centre
- All manifolds
Related guides: How much underfloor heating pipe do I need?, Balancing UFH loops and Zoning, thermostats and wiring centres.
Size your manifold free with MaxHeatUFH ProLoop. Add your rooms and floor type, and get a loop design with the port count, manifold and full kit list with prices. Start your design
Frequently asked questions
How many loops can a UFH manifold have?
MaxHeatUFH manifolds go from 2 to 12 ports, one loop per port. For more than 12 loops, use two manifolds.
Is a 2 port manifold 2 loops or 1?
2 loops. Each port has a flow and a return connection, one on each bar.
How many m² can one UFH loop heat?
About 12 to 14m² for a 16mm loop at 150mm centres, allowing for tails. At 100mm centres it is about 8 to 9m².
Do I need a thermostat for every loop?
No. You need one thermostat per zone, usually per room. A room with three loops has one thermostat that opens all three actuators.
Can I have unused ports on a manifold?
Yes. Fit a blanking cap and keep that port closed. A spare port is useful if you plan to heat another room later.
Should all loops on a manifold be the same length?
As close as you can. Even lengths balance more easily and heat more evenly. An auto-balancing manifold copes better with uneven loops.
Can two rooms share one loop?
It is better not to. A loop through a wall cannot be controlled per room and the pipe in the wall is at risk. Give each room its own loop.
Sources: Polypipe solid floor UFH installation guide, Polypipe UFH existing floors installation guide, Wavin stainless steel manifold data sheet