When there’s no room for a standard buffer vessel in your heat pump system, the Aquinox Pancake Buffer Vessel fits where nothing else will.
Starting from just 200mm tall and available in diameters up to 600mm, it’s designed to sit directly above or below a hot water cylinder, turning dead space into functional system volume. Fundamentally, the Pancake Buffer Vessel serves as an ideal solution for siting what can be an essential component when space is very limited.
The PBV‘s ultra-flat profile measures from 200mm tall up to 410mm, and comes in three different diameters; 475mm, 550mm, and 600mm.
Manufactured from stainless steel with fully customisable connections, the Pancake Buffer Vessel is purpose-built for heat pump installations where space is tight, and performance can’t be compromised.
The inclusion of a full-diameter baffle plate reduces distortion, and promotes stratification within the vessel.

| Model Code | Volume (L) | Overall Dimensions (mm) |
|---|---|---|
| 475mm Overall Diameter | ||
| APBV15A | 15 | 200x475 |
| APBV20A | 20 | 230x475 |
| APBV30A | 30 | 320x475 |
| APBV40A | 40 | 410x475 |
| 550mm Overall Diameter | ||
| APBV20B | 20 | 200x550 |
| APBV30B | 30 | 240x550 |
| APBV40B | 40 | 305x550 |
| APBV50B | 50 | 360x550 |
| 600mm Overall Diameter | ||
| APBV30C | 30 | 200x600 |
| APBV40C | 40 | 250x600 |
| APBV50C | 50 | 300x600 |
| APBV60C | 60 | 360x600 |
| APBV70C | 70 | 410x600 |
Ultra-flat buffer vessels, providing a highly effective solution to space-limited heat pump installations that require both a buffer vessel and a cylinder.
The Pancake Buffer Vessel can be positioned above or below a heat pump cylinder.
Yes. It is designed for installations where space is limited, but performance can not be compromised. It allows the system to perform at the standard of a regular buffer vessel.
Yes. As specialists in custom-made cylinders, the Pancake Buffer Vessel can be customised to fit your requirements. This includes the connection sizes, positions, and quantities.
The size of buffer vessel you need depends on your heat pump’s output and your system’s total water volume. Most heat pump manufacturers specify a minimum system volume in their installation manuals. If your heating circuit (radiators, pipework, underfloor heating) doesn’t meet that minimum, a buffer vessel bridges the gap.
As a rough guide, many installers work from 10 to 20 litres per kW of heat pump output, but this varies depending on the system. Underfloor heating circuits tend to hold more water than radiator systems, so they may need a smaller buffer or none at all.