A buffer tank for a heat pump: when it is needed

Whether a heat pump needs a buffer tank depends on the specific model and heating system. Some systems require one, others work without it. A tank is not an automatic accessory – it makes sense where it solves a specific problem.

What it is for

• it ensures the minimum water volume in the system required by the manufacturer,
• it reduces the number of compressor starts when the heat demand is low,
• it helps with defrosting – the heat for defrosting is taken from the water in the system,
• it separates circuits in more complex systems with several branches.

When it is usually needed

• the system has a small water volume or many thermostatic heads that can close off the flow,
• there are several heat sources in the system – for example a fireplace with a heat exchanger (A heat pump and a backup heat source: fireplace, boiler or electricity),
• several heating circuits with different temperatures.

When it is often not needed

With a simple underfloor heating system that has sufficient water volume and open circuits, some heat pumps can manage without a tank. The requirement of the manufacturer of the specific model is decisive.

Disadvantages of an unnecessary tank

• it takes up space in the plant room,
• it has heat losses,
• it increases the price of the installation,
• if badly connected, it can reduce efficiency.

Not to be confused with a hot water tank

A buffer tank is part of the heating circuit. A hot water tank provides water for the bathroom and kitchen – Hot water heating with a heat pump: tank, temperature and savings.

We will design the right connection

We will assess whether a tank is needed when designing a Daikin heat pump for your system. Related: Air-to-water heat pump installation: how it works. Contact us.