The Spirotech SpiroTrap MB3 28mm (UE028WJ) extends the proven MB3 magnetic dirt
separation platform to 28mm pipework, making it the direct choice for
larger residential systems, light-commercial plant rooms, and multi-zone underfloor heating
where 28mm flow and return pipework is the norm. Using the same full-flow settling principle
with an external neodymium magnet, it removes particles from 5 μm
without restricting flow or requiring system isolation to service.
5 μm
Min particle removal
Kvs 10.13
Flow coefficient
INSTALLER NOTE — SYSTEM POSITION
As with all SpiroTrap MB3 variants, install vertically on the return pipework with the socket pointing downward. For 28mm systems, ensure pipework is adequately supported — the MB3 28mm weighs more than the 22mm variant. The drain valve must be orientated for clear access.
HIGHER-FLOW SYSTEMS — SIZE SELECTION
The 28mm MB3 handles up to 2.0 m³/h, compared with 1.3 m³/h for the 22mm version. If your system peak flow exceeds 2.0 m³/h, move up to the threaded SpiroTrap MBL UE125WJ (Rp 1¼", up to 3.6 m³/h). For systems below this threshold, the MB3 delivers a constant low pressure drop with no in-line restriction.
SYSTEM PAIR
For maximum protection, pair the UE028WJ with the UA028W SpiroVent RV2 28mm air deaerator on the flow pipe (hottest point of the circuit). Together, this combination eliminates both dissolved air/microbubbles and magnetic and non-magnetic dirt — the root causes of up to 13% gas waste in fouled central heating systems.
28mm Full-Flow Settling
The MB3 28mm widens the internal cross-section to reduce flow velocity, settling particles into the collection chamber by gravity and magnetic attraction. There is no in-line mesh or cartridge to clog, and no pressure spike when the chamber fills.
Larger Collection Chamber
With a filter volume of 0.39 litres (vs 0.36 l on the 22mm), the 28mm unit handles the higher debris volumes typical of larger systems without requiring more frequent service calls.
Slide-Off Magnet Maintenance
The neodymium magnetic jacket slides down and off in seconds. Once removed, opening the drain valve flushes the settled sludge and magnetite under system pressure — no shutdown, no mess. Replace the magnet and the unit is immediately back in service.
Reversible Flow Direction
Flow may enter from either side, giving installers flexibility when pipework routing doesn't align with a fixed-direction unit. The drain valve orientation is also adjustable post-installation via the compression swivel.
Technical Specification — SpiroTrap MB3 28mm (UE028WJ)
| Connection & Hydraulics |
|---|
| Article Number |
UE028WJ |
| Product Type |
SpiroTrap MB3 — 28mm — Magnet — Universal Connection |
| Connection |
28mm compression ring (with couplers) |
| Flow Direction |
Variable (reversible) |
| Max Flow Rate |
2.0 m³/h |
| Kvs Value |
10.13 m³/h |
| Inlet/Outlet Offset |
0 mm (in-line) |
| Operating Limits |
|---|
| Max Operating Pressure |
10 bar (PN 10) |
| Temperature Range |
0 – 110 °C (continuous) |
| Max Glycol (Ethylene) |
50% v/v |
| Suitable for Heating |
Yes |
| Suitable for Cooling |
Yes |
| Closed System |
Yes |
| Open System |
No |
| Solar Applications |
No |
| Physical & Construction |
|---|
| Housing Material |
Brass |
| Magnet Type |
Neodymium (external jacket) |
| Separator Principle |
Full-flow with settling |
| Filter Volume |
0.39 litres |
| Construction Length |
112 mm |
| With Drain Tap |
Yes |
| Compliance & Warranty |
|---|
| Design Standard |
EN 13445 |
| CE Marking |
2014/68/EU (Pressure Equipment Directive) |
| Warranty |
20 years — SpiroLIFE |
Frequently Asked Questions
When should I choose the 28mm MB3 over the 22mm version?
Choose the 28mm UE028WJ when the system flow and return pipework is 28mm. While the hydraulic performance figures are close, using a 28mm-to-22mm reducer to fit the smaller unit introduces turbulence and a small pressure drop at the reducer joints. The 28mm unit's Kvs of 10.13 also supports the higher flow rates typical of larger-boiler, multi-zone, or commercial systems.
Does the 28mm MB3 need any special pipe support?
The MB3 28mm is heavier than the 22mm variant. In horizontal pipework arrangements, ensure pipe clips are positioned within 200mm of each connection. The unit itself should remain vertical with the drain socket at the bottom — pipework angle can be accommodated with standard fittings, but the separator body must be plumb.
Is this product compatible with heat pump systems?
Yes. Spirotech includes a dedicated heat pump installation diagram for the MB3/RV2 combination. Fit the MB3 28mm on the return to the heat pump indoor unit; fit the UA028W SpiroVent RV2 on the flow. For installations requiring hydraulic separation between the heat pump and distribution circuit, use the SpiroCross AX100J or AX125J instead.
How does the MB3 differ from a standard magnetic boiler filter?
A magnetic boiler filter uses a mesh element that must be periodically removed and cleaned — the process is messy and requires system depressurisation. The MB3 uses gravity settling plus a magnetic field; there is no mesh element. Servicing is done under pressure in under two minutes with no dirty spillage, and there is no consumable element to replace.
What is the annual maintenance requirement?
Spirotech recommends draining the collection chamber once a year, typically at the start of the heating season. Remove the magnet sleeve, open the drain valve into a container, flush briefly, close, replace the magnet. If the system is particularly dirty in year one (e.g. after a power-flush or new build commissioning), a mid-season check is advisable.
