I have a leak from the overflow pipe on my heat pump. 

As the water heats up you may see 4 -5 litres drip out over the course of a day.

Is the dripping all the time, or just when the unit is heating up? It’s normal to see water dripping from the overflow pipe while the unit is heating up. The dripping is a reflection of the temperature in the air, so you should expect to see more dripping in summer than during the cooler months.

The overflow pipe shouldn’t be a steady flow like you see from a tap – that’s not normal and should be looked at by a professional.

If you can take photos or video of where the leak is coming from it can help to diagnose the issue remotely.