HEAT PUMP & MULTI-CIRCUIT SYSTEM COMPONENT — HYDRAULIC SEPARATOR WITH AIR & DIRT SEPARATION
The Spirotech SpiroCross AX100J is a Rp 1" brass low-loss header
(hydraulic separator) that combines three essential functions in a single compact unit:
hydraulic balancing between a primary heat source circuit and a secondary distribution circuit,
continuous microbubble air deaeration, and neodymium magnetic dirt separation.
Developed using Computational Fluid Dynamics (CFD) modelling and validated on a
TÜV-certified test rig, it is specifically engineered for heat pump installations,
underfloor heating systems, and any multi-circuit HVAC arrangement where hydraulic independence
between the primary pump and secondary distribution pumps is essential for stable, efficient operation.
3-in-1
Hydraulic + Air + Dirt
INSTALLATION — ORIENTATION AND PIPEWORK
The AX100J must be mounted in horizontal pipework with the integral air vent on top. The unit has no directional arrow — either connection may be used as inlet or outlet, and flow may be directed to either side. To ensure the best air separation efficiency, connect the higher-temperature circuit to the upper connections. Allow at least 100mm straight pipe before and after the unit. The piping normally supports the unit weight (6.5 kg dry).
PRIMARY / SECONDARY CIRCUIT REQUIREMENT
The SpiroCross AX100J is designed for systems with a separate primary circuit (heat source) and secondary circuit (distribution), each with its own circulating pump. If your system has only a single circuit with one pump, a standard SpiroTrap MB3 and SpiroVent RV2 combination is the appropriate specification. The AX100J is not a single-circuit filter.
THREE FUNCTIONS IN ONE — COST AND SPACE SAVING
By replacing a separate low-loss header, dirt separator, and air deaerator with a single unit, the AX100J reduces the number of system connections from eight to four, saving installation time, reducing potential leak points, and significantly reducing plantroom footprint. The SpiroTube technology ensures minimal fluid mixing between the primary and secondary loops — maintaining the temperature differential that heat pump COP depends upon.
Hydraulic Balancing — SpiroTube Technology
The internal SpiroTube element creates a low-velocity central zone that prevents direct short-circuiting between primary and secondary flows. This compensates for flow differences between the primary heat pump pump and multiple secondary zone pumps, ensuring each secondary zone receives stable, correctly tempered water regardless of how many zones are active simultaneously — essential for heat pump COP stability.
Neodymium Magnetic Dirt Separation
A powerful neodymium magnet captures magnetite and magnetic debris in a large collection chamber that can be drained while the system remains fully operational. The large chamber capacity means infrequent draining is needed. Collected dirt is discharged quickly under system pressure — no system shutdown, no tools required.
Factory-Fitted Integral Air Vent
The factory-installed automatic air vent continuously removes circulating air and microbubbles without manual intervention. Unlike add-on vents, this is positioned at the natural high point of the SpiroTube's collection zone — the most effective location for bubble coalescence and release in a low-loss header format.
CFD-Developed & TÜV-Validated
Spirotech used Computational Fluid Dynamics to optimise internal flow geometry and validated the design on a TÜV-certified test and measurement rig as well as real-world installations. The AX-J series is not an adapted off-the-shelf product — it is a purpose-engineered heat pump and multi-circuit component.
Technical Specification — SpiroCross AX100J (Rp 1")
| Connection & Hydraulics |
|---|
| Article Number |
AX100J |
| Product Type |
SpiroCross AX-J Hydraulic Separator — Rp 1" threaded fitting |
| Connection |
Rp 1" BSP internal thread |
| Max Flow Rate |
2.0 m³/h |
| Max Flow Velocity |
1.0 m/s |
| Operating Limits |
|---|
| Max Operating Pressure |
10 bar (bar-g) |
| Max Temperature |
110 °C |
| Medium |
Water / glycol (max 50% v/v) |
| Design Standard |
EN 13445 |
| CE Marking |
2014/68/EU (Pressure Equipment Directive) |
| Construction Materials |
|---|
| Body |
Brass |
| Connections |
Brass |
| Fittings |
Brass |
| Deaeration Cap |
Brass |
| Valve Sealing |
Viton |
| Float |
Polypropylene (PP) |
| Drain Valve |
Brass |
| Spirotube Tube |
S235 JRG2 (structural steel) |
| Spirotube Wire |
Copper |
| Spirotube Solder |
Tin (SnCu3) |
| Magnet |
Neodymium |
| Physical Dimensions |
|---|
| Total Height (H) |
462 mm |
| Lower Height (h) |
135 mm |
| Connection Height (h1) |
144 mm |
| Upper Height (h2) |
183 mm |
| Length (L) |
236 mm |
| Body Diameter (D) |
84 mm |
| Width (b) |
53 mm |
| Min clearance above (x) |
>100 mm |
| Min clearance below (y) |
>50 mm |
| Air Vent Port (e) |
G 3/4" |
| Drain Port (e2) |
R 1/2" |
| Internal Volume |
1.3 litres |
| Dry Weight |
6.5 kg |
| Testing & Certification |
|---|
| Leakage Test |
Yes — test medium: air |
| Design & Manufacturing |
2014/68/EU compliant |
| Warranty |
|---|
| Warranty |
20 years — SpiroLIFE |
Frequently Asked Questions
Why does a heat pump installation need a low-loss header / hydraulic separator?
Heat pumps are variable-output devices that modulate flow to maintain efficiency. If the heat pump primary circuit and the secondary distribution circuit share the same pump, flow changes in one circuit directly affect the other — zone valves opening and closing cause pressure fluctuations that destabilise the heat pump refrigerant circuit. A low-loss header like the AX100J hydraulically decouples the two circuits, allowing each pump to operate independently — essential for stable COP and heat pump longevity.
Can the AX100J be used for both heating and cooling systems?
Yes. The AX100J is suitable for both heating and cooling applications with water or glycol up to 50% v/v. For cooling, connect the cooler (chiller or heat pump evaporator side) to the upper connections to ensure the coldest water is where the SpiroTube collects dissolved gas most effectively.
What is the maximum heat pump size the AX100J can support?
With a maximum flow rate of 2.0 m³/h at up to 1 m/s, the AX100J suits heat pump primary circuits typically up to approximately 10–14 kW output at a standard Δt of 5–7 K (typical heat pump primary ΔT). For larger systems, the AX125J (Rp 1¼", 3.6 m³/h) is the appropriate step up.
Does the AX100J replace the need for separate SpiroTrap MB3 and SpiroVent units?
Yes — for a dual-circuit system, the AX100J performs the hydraulic separation, air deaeration, and magnetic dirt separation that would otherwise require three separate devices and eight connection points. For a single-circuit combi-boiler system without hydraulic separation requirements, a separate MB3 and SpiroVent RV2 pairing remains the correct specification.
How should the expansion vessel be connected relative to the AX100J?
Spirotech recommends connecting the expansion vessel on the suction side of the pump or circulator, as with all hydronic system piping. The AX100J installation diagram (available from Spirotech) shows the expansion vessel connected to the secondary circuit suction point, not directly to the separator.
Is the AX100J suitable for retrofit into an existing heat pump installation?
Yes — the AX100J is designed for new build, refurbishment, and retrofit applications. The Rp 1" BSP threading suits standard plant room pipework. On a retrofit, the primary and secondary circuits will need to be temporarily disconnected and the existing header removed. Spirotech recommends a system power-flush before fitting to ensure the new separator begins with clean system water.
