Quick Composting FAQs

Quick HOTBIN question and fast answers

Does the lid need to be closed at all times?
YES, unless adding waste, keep the HOTBIN lid closed at all times.
How does air get into the HotBin?
The air inlet mesh is located in the front wall, at the bottom (view schematic). Ensure the inlet is not covered, for example, with snow, soil or buckets.
Where can I get more bulking agent?
Make your own by cutting up twiggy plant material or using your own 'shredder/chipper'. Purchase from the HOTBIN shop or local garden centre; your local council many also shred trees and leave them piled locally.
How do I convert compost (or food waste) volume (litres) to weight (kgs)?
Food waste has a bulk density of roughly 50%, so a full 5 litre kitchen caddy would weigh approximately 2.5 kg. Compost has a bulk density of roughly 50%. A 10 litre bucket would weigh approximately 5 kg.
If the process has stopped, what can I do?
By stopped, let us say the temperature was above 50°C and has fallen back towards 20°C or ambient, Add a caddy (approx 3-5 Kg) of new food waste, stir into top, leave for 24-hours. The internal temperature should start to rise.
Should my compost smell ‘earthy’?
Yes, this is just how it should smell. Mature compost smells "earthy" or a little musty.
Will I need more than one HotBin?
The HOTBIN is designed for a 4 to 5 person house generating 3-5 Kgs of food waste with medium garden generating 40 Litres of grass. Please remember when comparing with traditional ‘cold’ bins sizes, your waste will decompose 32 times faster when its operating at 60°C . Only if you have exceptionally large household, very large garden or lawn would we suggest you consider purchasing two bins.
Is the HOTBIN rat proof?
Vermin control experts indicate rats can and have eaten through almost everything at one time or another including all plastics, metal wires and concrete. It is impossible to state or guarantee the HOTBIN is ‘100% rat proof’. The HOTBIN is designed to minimise the attraction to rats. Read more.
Do I need to layer green and browns in the HOTBIN?
There is no need to layer 'green and browns'. It is important you chop/shred waste (preferably <2cm but always <4 cm) and to mix in both shredded paper and/or torn cardboard and some bulking agent.
Composting weed seeds, weed seeds in the HOTBIN?
Weed seeds may survive being composted in a cool heap, but most will be killed in a hot HOTBIN. Even persistent horrors such as celandine, docks, bulbous buttercup, ground elder and bindweed will not survive sustained exposure to hot composting temperatures of 40-60°c.
I have steam coming out of the valve is this OK?
Steam is good indicator that the temperature is rising and the process is working. Occasionally when the air temperature drops, the steam leaving the compost (via the valve) will condense before it drifts into atmosphere. You might see small drips on the lid and sidewalls as it drains away. This is normal so please do not worry.
What is the HOTBIN made from?
The HOTBIN is made from Expanded Polypropylene (EPP) - A robust engineering material - For more information click here.
What if my compost appears very woody?
It is very easy to add too little bulking agent, so err on the side of caution and ensure you add a couple of handfuls of it each time you add fresh waste. If you have a batch of compost that comes out looking too woody  – just take it out, store and re-use it as bulking agent again.
What should I not add to my HOTBIN?
A brief list of things on the DO NOT add to HOTBIN
  • Liquids such as water, urine, soups, gravy (read why at the 'too wet' post)
  • Hot BBQ/Coal/Wood ashes (leave to cool, see BBQ/Wood/Coal ash posts)
  • Glass, plastic, rubber, paint, metals, solvents, petrol, oil
  • Large frozen items (leave to thaw and cut up)
  • Contents of your vacuum cleaner
Can I disguise my HOTBIN?
  • Use a Wheelie bin type wooded screen to fence it off
  • Add a wheelie bin printed sheet (flowers, leaves etc). These will stick to the HOTBIN
  • Cover it with a green sheet (eg a BBQ cover)  
Is the HOTBIN only available in black?
Yes. Why black - well it just happens to be the default colour of the EPP material. Hundreds of colours are possible however colouring the bead adds signifiant cost.
How long will the HOTBIN last?
The EPP ARPRO material is very durable and weather proof. If looked after it should keep you in fresh compost for upwards of 10 years.
Does the HOTBIN come with a guarantee?
Yes, the HOTBIN comes with a 3-year manufacturing guarantee on the unit itself. The accessories which are supplied with the HOTBIN however come with a 1-year guarantee.
Does the HOTBIN need assembling?
No, your HOTBIN arrives ready assembled. Just secure the cam straps and open the top valve by 2mm.
Is 80°c too HOT?
The maximum temperature bacteria can operate at is 70-75°c, it is rare for the HOTBIN to go much above 60°c. Double check you are reading the Celsius scale and not Fahrenheit (60°C = 140°F).
Should I wrap food waste in newspaper?
No, not in the HOTBIN. In cold composting this is sometimes recommended to try and prevent flies getting to the food waste. Above 40°c, the heat in the HotBin kills flies. The closed lid prevents them getting in and even id they do get in (eg when lid open), as soon as the HOTBIN reaches more than 40°c they are killed off. In the HOTBIN, wrapping food waste has a negative effect - the paper will get moist and act as a barrier to oxygen. The material inside will rot rather than aerobically compost.
Can I add worms to the HOTBIN?
You do not need to add worms into the HotBin. Worms are however beneficial to composting and can be added. Do not add them into the upper active layer (60°C will kill them). Instead, add them into the cooler bottom layer of material via the HOTBIN hatch.
What is the compost I get at the garden centre?
Compost sold at garden centres should be stamped as conforming to the PAS100 standard – it will be stable and mature, and below a set sieve size.
What affect does a cold wind have on my compost?
Cold winds dramatically increase convectional cooling. A heap can lose heat up to 100 times faster in a cool wind over a warm still day. All moving air will cause significant heat loss, HOTBIN is well insulated and does not have this problem.
What is mulching compost?
Mulching compost is not completely mature or stable. If you look carefully, you will see lots of twigs and discernible pieces of plants. It is still decomposing and is not ready to use as a soil improver or growing medium - it will ‘rob’ the soil of oxygen and potentially nitrogen.
This is good if you want to mulch, but not if you're attempting to improve or fertilise your soil!
How much compost will the HOTBIN produce each year?
With typical domestic food and garden waste loading, the HOTBIN produces approximately 2-3 Kg of mature compost for every 10Kg of waste added.
  • The average user will empty the HOTBIN 4 times a year. Each time about 60-70 litres are taken out.
  • When you pull out the compost it will fluff up and become bulkier. It can easily expand and fill a wheel barrow (about 150 litres).
  • Please be aware the figure vary enormously - the more that goes in, the more compost comes out. The higher the temperature achieved the faster it comes out.


11 October 2019  |  HOTBIN Composting

New HOTBIN models have a tap to collect liquid fertiliser but can this be retrofitted to an original HOTBIN?

28 January 2019  |  HOTBIN Composting

The HOTBIN base layer is crucial to begin the production of heat in the HOTBIN. Here are 5 types of waste however that should not be soley used to create a base layer.

27 January 2019  |  HOTBIN Composting

A good base layer provides the foundation of a healthy and happily working HOTBIN. Here are some hints on creating one.

25 January 2019  |  HOTBIN Composting

Will a cold bin go anaerobic? What can you do if the HOTBIN temperature is dropping but you are lacking waste to add into the HOTBIN?

7 December 2018  |  HOTBIN Composting

Here is why you need to keep adding bulking agent as we explain what it is and what role it plays in your compost heap.

6 September 2018  |  HOTBIN Composting

The HOTBIN lid will stay in place when fully opened to ease the feeding process of the HOTBIN.

10 August 2018  |  HOTBIN Composting

Here are the top 5 common mistakes made when hot composting with the HOTBIN.

4 June 2018  |  HOTBIN Composting

Card or paper in the HOTBIN is essential, however pre-soaking it can cause problems with the HOTBIN's operation - here is why we advise against it.

29 March 2018  |  HOTBIN Composting

Unlike other compost bins and heaps, the HOTBIN does not need to be situated in direct sunlight.

14 February 2018  |  HOTBIN Composting

There are a variety of domestic wood based products which you can compost in the HOTBIN. Some are found in the house whilst others are in the garden.

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