The Ideal Heating 50 Litre Buffer Tank (AH700437, BT50) is a compact thermal storage vessel that increases system water volume to improve heat pump performance, reduce cycling, and smooth hydraulic operation. It provides a larger reserve of heated water than the 25L variant, making it well suited to larger properties or systems with multiple heating circuits.
Like the smaller BT25, the tank offers flexible horizontal or vertical wall-hung installation and is compatible with Ideal Logic Air and HP290 air source heat pumps, as well as biomass and conventional gas or oil boilers. Its insulated construction reduces standing losses, helping stabilise flow temperature, improve defrost recovery, and protect the compressor from excessive short-cycling.
6 bar
Max Working Pressure
-10 to +110°C
Operating Temperature
Class C
Energy Efficiency
Important: Wall Loading & Expansion Vessel Sizing
The tank must be fixed to a load-bearing wall of adequate strength — this is the installer's responsibility. The system's expansion vessel must also be sized to account for the buffer tank's water content, in addition to the rest of the heating circuit.
Please Note: 50L vs 25L — Check System Sizing
This is the 50 litre (BT50, AH700437) variant, which is physically larger than the 25L (BT25, AH700436) model. Confirm the buffer volume required by the heat pump manufacturer's system design guidance, particularly for larger or multi-zone installations, before ordering.
Good to Know: Compatible Heat Sources
Suitable for use with Ideal Logic Air and HP290 heat pumps, biomass boilers, and traditional gas or oil boilers — making it a versatile addition to renewable and conventional heating systems alike.
Greater Buffer Capacity
The 50L water volume suits larger properties or systems with multiple heating zones, giving a bigger thermal reserve than the 25L model.
Reduces Short-Cycling
Added system volume stops the heat source switching on and off too frequently, improving efficiency and extending compressor or burner lifespan.
Flexible Wall Mounting
Can be installed horizontally or vertically on a wall bracket, suiting plant rooms, airing cupboards, or garages where floor space is limited.
Insulated Shell
The tank body is insulated to minimise standing heat loss, so stored thermal energy isn't wasted between heating demand cycles.
Improves Defrost Performance
The larger stored water reserve helps maintain heat output to the property during an air source heat pump's defrost cycle.
Dual Connection Sizing
Fitted with both 1″ and 1¼″ connections, giving installers flexibility to match existing pipework without extra reducers.
| Product Identification |
| Manufacturer |
Ideal Heating |
| Product |
50 Litre Buffer Tank (BT50) |
| Manufacturer Part Number (MPN) |
AH700437 |
| Compatible With |
Ideal Logic Air and HP290 air source heat pumps; biomass and conventional gas/oil boilers |
| Technical Specification |
| Storage Capacity |
50 litres |
| Energy Efficiency Class |
C |
| Waste Heat Loss |
48 W |
| Maximum Working Pressure |
6 bar |
| Operating Temperature Range |
-10°C to +110°C |
| Connections |
1″ and 1″¼ |
| Mounting Orientation |
Horizontal or vertical, wall-hung |
| Colour |
Blue |
| Dimensions |
| Diameter (ØA) |
273 mm |
| Overall Height (I) |
1000 mm |
| Body Height (H) |
192 mm |
| Width (E) |
600 mm |
| Depth (F) |
343 mm |
| Wall Bracket Centres (J) |
40 mm |
What's the difference between the 50L and 25L buffer tanks?
The 50L (BT50, AH700437) and 25L (BT25, AH700436) share the same connection sizes and pressure/temperature ratings, but the 50L is taller and wider to accommodate its larger water volume, with a slightly higher waste heat figure. Choose based on the heat pump manufacturer's minimum system volume requirement.
Which heat pumps is this buffer tank compatible with?
It's designed for use with the Ideal Logic Air range and the Ideal HP290, and is also suitable alongside biomass boilers and traditional gas or oil boiler systems.
Can the buffer tank be mounted horizontally?
Yes, the tank supports both horizontal and vertical wall-hung installation, giving installers flexibility depending on available plant room space.
Do I need to resize my expansion vessel when adding a buffer tank?
Yes. The additional water volume of the buffer tank must be included when calculating the system's total expansion vessel requirement, in line with the manufacturer's installation guidance.
What connection sizes does the buffer tank use?
The BT50 is fitted with 1″ and 1¼″ connections, matching the smaller BT25 model, allowing it to be plumbed into most domestic and light-commercial heat pump and boiler circuits.
