My HOTBIN will not go above 40c any more

5 February 2014  |  HOTBIN Composting

I can't get my HOTBIN above 40°c any more!

Here at HOTBIN we are passionate about our brand promise that given the right volume and mix of waste everyone can hot compost at 40-60°c. We have a few rare situations where customers have been composting successfully at 60°c for a while, nothing obvious has changed and yet the HOTBIN sticks persistently at 30-40°c. We have termed this a stalled HOTBIN.

Who is affected by stalling?

A stalled HOTBINs are where it has been working perfectly for months at 40-60°c then suddenly it will not rise above 40°c. (Not to be confused with customers who have never reached 60°c). Stalling is not a common occurrence and there are only a handful of reported cases.

Why does it happen?

It is caused by restricted airflow through the base layer. (Think of the HOTBIN as a fire in the chimney, you add new waste onto the fire to fuel it. As the heat rises fresh cold air is drawn in at the base. This air is drawn up through the base layer. If not enough air flows, the bacteria are restricted and hence the heat produced is restricted.

What causes restricted airflow?

The HOTBIN works under many different waste conditions. However, we have identified the causes that can tip the balance and create restricted airflow: dense, compressed, wet layer of either paper or grass.

Top tips for fixing a stalled HOTBIN

  • Empty out the base layer at least every 6 months. Longer and it will lead to ultra compression of the base layer and possibly build up a sticky humus gloop. If you have been using the HOTBIN for more than 6 months without emptying, check to see if your base plate is plugged. The plates are designed to work with the holes covered in compost – plugged means they are filled with a sticky humus gloop If blocked with gloop - rinse the plate with water. After each emptying, to reduce the chance of plugging, sprinkle a 1 cm layer of wood chip on the base plate.
  • Always add bulking agent – this is critical with Food waste, but it will also help prevent compression of any waste. Stir the top half of bin to help aerate and break up any dense layers.
  • Check the base layer for thick dense layers. eg a solid layer of wet grass or compressed wet paper.
  • Check the mesh plate for leakage of water/leachate. If lots of leachate cross check to see if your real issues is that your waste is too wet.

Remember: In hot composting, paper fixes wetness, wood chip helps aeration. You cannot balance wet waste by adding wood chip bulking agent, nor can you fix poor aeration by adding paper. You need to check how much bulking agent has been added.