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Hot Compost Bins

The Best Hot Composters and How They Work

By Daniel Woodley at DIY Gardening

Home composting has become popular in recent years, and during the Covid-19 lockdowns, many of us have been spending time in our gardens, so if you’re thinking about getting started, go for it!

There are many benefits to composting:

  • Great for the environment as less kitchen waste goes to landfill or recycling centres.
  • Fun and educational for children.
  • It doesn’t take up much space in the garden – most composters are smaller than a wheelie bin.
  • Free compost and fewer trips to the garden centre.
  • Less plastic packaging waste, you might be surprised at how many bags of compost the average gardener buys.

But what about hot composting?

What is it?

How does it differ from regular composting, and do the results live up to the claims?

My name is Daniel Woodley, and welcome to my guide to the best hot composters and how to get the most from them.

Daniel Woodley

Daniel Woodley

Do Hot Composters Work? 

Before I go into how a hot composter works and how it compares to a regular composter, check out the short video below from a small local group called “Norfolk Master Composters”, you can find them on Facebook here.

As you can see from the footage, this hot composter produced good quality compost at the first attempt, and the owner started this pile in January, which is a cold month. 

I would expect the hot composter to deliver results much quicker during warmer months (more about that later).

The bin shown in the video is a HotBin which you can find here.

Comparing a Hot Composter to a Regular Compost Bin 

To put it simply, a compost heap, pile or bin that is warm will produce compost much faster than a cold composter or open heap.

You can expect a hot composter to produce usable compost in 30-90 days, depending on how hot the bin is and what you put into it.

According to the RHS, a regular garden compost pile takes between 6 months and 2 years, while a larger council-run compost heap takes up to 1 year.

Hot composters are designed to hold in the warmth created by the decomposing matter, while an open pile or regular compost bin loses this heat much quicker.

Pros

  • Fast turnaround time. The Berkley Method to hot composting can produce results in 18 days.
  • Less space needed as you can empty the composter more frequently.
  • Sterilisation – the heat kills off pathogens and weeds, which is a common problem with many cold composters.
  • It’s fun. You can control the decay rate by adding fish and bone fertiliser (speeds it up) or sawdust (slows it down).
  • The material inside a hot composter doesn’t reduce in size as much as a slow/cold composter, so you get more compost.
  • Fewer flies, insects and vermin as it’s too hot for them.

Cons

  • The cost – hot composters cost more than regular compost bins.
  • If you live in a cold climate, they don’t work as well during the winter.
  • They require more frequent turning to aerate the contents.
  • Hot composters require lots of attention and adjustments, and it might take a while to get the hang of it.
  • Composting, in general, is easy to get wrong, and hot composting even more so. It’s not simply a case of chucking everything into a bin and leaving it.

The Best Hot Composter For the UK

The HotBin is my #1 choice for the UK.

Here’s why:

The HotBin has more insulation than any of the other hot composters I examined, and given that many parts of the UK get very cold in the winter, I feel this is important.

There are other products on the market that hold in the heat, but after looking at the thickness and quality of the insulation, I don’t feel they would hold well in a cold northern winter.

The HotBin is a sealed unit, and you see how thick the insulation is in these photos:

Hotbin insulation

Also, the HotBin composter looks like a very well-engineered product. It’s airtight, has straps to stop the door from coming loose, has a sloping floor for liquid drainage, has a drainage hole and cap and comes with a carbon filter to capture unwanted odours.

I couldn’t find a better hot composter for sale in the UK despite looking everywhere.

Overview

The HotBin composter comes in two sizes; a 100-litre mini version and the standard 200-litre version, which is about the size of a wheelie bin.

Don’t forget that you don’t need to wait a year to get compost, so the smaller HotBin might be your best option, especially if space is limited or you don’t create much compostable waste in your home/garden.

100-litre HotBin:

115cm high x 45cm wide x 45cm deep.

Height with lid open: 142cm.

Depth with lid open: 53cm.

5cm recyclable polypropylene insulation.

Weight: 4kg unboxed.

Thermometer.

Raking tool.

Aeration valve to control the temperature.

Biofilter to reduce odour.

Sloping internal base so any liquid funnels to the drainage cap. Waste liquid can be used as a fertiliser.

Optional stand.

3-year warranty.

200-litre HotBin:

115cm high x 55cm wide x 55cm deep.

Height with lid open: 142cm.

Depth with lid open: 63cm.

5cm recyclable polypropylene insulation.

Weight: 8kg unboxed.

Thermometer.

Raking tool.

Aeration valve to control the temperature.

Biofilter to reduce odour.

Sloping internal base, so any liquid funnels to the drainage cap. Waste liquid can be used as a fertiliser.

Optional stand.

3-year warranty.

Eco Credentials

There is no doubt that home composting is far more eco-friendly than buying compost from garden centres, but how eco-friendly is the HotBin?

Currently, neither of the HotBins are made from recycled plastic, which is disappointing. However, the ARPRO (expanded polypropylene) used in the construction can be recycled.

It’s also worth noting that the expanded polypropylene found in the HotBins is around 95% air and only ~5% plastic. Hence, there’s actually very little plastic used in the construction, which is evident in the product’s weight. For example, the Mini HotBin weighs only 4kg, including the thermometer, valve and raking stick.

Awards, Reviews and Ratings

The HotBin won product of the year at the Chelsea Flower Show in 2019 (source).

On Amazon, the HotBin Mini currently has a rating of 4.7 out of 5 based on 40 reviewers; the lowest single rating is 3 stars (source).

The Family Grapevine, a website and publication based in Sussex, rated the Hotbin 4.5 stars (source).

Alternatives

The obvious alternative to a hot composter would be a regular compost bin, but these take much longer to produce compost and are notorious for not killing off pathogens and weeds as well as attracting vermin and pests.

The next best hot composter in the UK is the Aerobin. However, I’ve looked at this product and in my opinion, the insulation is far too thin. The company behind the Aerobin is Australian, and while this product may work well in a warmer country, I feel it would struggle in cooler parts of the country in the UK.

It may work well in the far south of the UK, but I believe the Aerobin would get so cold during the winter months that it just wouldn’t work in northern areas.

There are a couple of advantages over the HotBin, so maybe those living in warmer parts of the UK could try it:

  • Cheaper.
  • Larger bin options – up to 600 litres.

The Aerobin installation video is below. As you can see, it’s not as well insulated and is perhaps more suited to a warmer climate:

Conclusion and Summary

Hot composters work very well and can produce usable compost in 30-90 days.

30 days – expect bulky mulch-like compost.

90 days – expect a fine compost for pots, baskets and borders.

If you live in a cooler part of the country, you should choose a very well insulated composter if you want to use it all year round.

Be aware that some foreign products are designed for different climates; they might not work so well in cooler parts of the UK.

Composting is eco-friendly and fun but can also be frustrating. It takes time to learn the correct ratios of green ad brown waste:

Too much brown waste, such as woodchips and larger twigs – cools the composter and can stop the process.

Too much green waste such as grass clipping, soft leaves, annual plants etc. – accelerates the process, but the lack of bulky materials can lead to sludge and slime.

I like that hot composters are sealed units that don’t seem to attract as many pests as open piles and the fact that they produce compost in a fraction of the time.

FAQs

What Produces the Heat Inside the Composter?

As the matter inside the composter decomposes, it produces heat. If the composter is well insulated, the increased temperature will accelerate the process.

In cooler climates, you can chuck in a hot water bottle to get the process started but hot composters don’t use any other form of artificial heat.

Should I Locate the Composter in Direct Sunlight?

Hot composters don’t need to be located in direct sunlight, and if they are, you may need to vent the excess heat to slow down the process or add some bulky brown waste to prevent slime from forming.

Do I Need to Buy Compost Accelerators or Similar Products?

Compost accelerators usually contain nitrogen to speed up or kick start the process; they are beneficial in cold, regular composters, which are notoriously slow to produce compost but are rarely needed in hot composters.

Can I Put All My Food Waste in a Hot Composter?

Unlike a regular cold composter, a hot composter will break down all food waste, including those from animals.

The key is to not overload the composter with too much of one thing as it requires the right ratio of materials to function correctly.

This pdf from HotBin lists everything you can put into a hot composter.

Do I Really Need a Hot Composter?

Regular cold composting works just fine but takes longer, doesn’t kill off all the weeds and pathogens, and you need to be more careful with what you put into a regular composter as it could attract pests before it’s had the chance to breakdown.

Author: Daniel Woodley

This guide to the best hot composters was created by Daniel Woodley at DIY Gardening and was last updated on the 21st of June, 2021.

Discover more of our compost and soil guides here and helpful hints and tips from Daniel over at the blog.

Daniel is a keen amateur gardener who’s trying to become more eco-friendly and is enjoying learning new things.

He also likes growing vegetables and fruits as well as his herbaceous border and container garden.

More About Daniel Woodley

Danny Woodley

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This guide to the best hot composters was created by the team here at DIY Gardening

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