 The hot bin, is it an overpriced compost bin or is it a brilliant piece of design? After having one for three years, I can tell you. So the question to start with is why would I need a hot bin? What are they doing? And for us, one of the key things was that we were producing a lot of vegetable waste, food waste from the kitchen, not edible stuff of course, all the stuff that the peelings and greens and so on that come off. And we wanted to put it somewhere that wouldn't attract rodents. We know we have bowls here and there's almost certainly rats around and we didn't want to put those things directly on an open compost heap. So we looked at some options and having had this recommended by a neighbour, we thought we'd take a crack and we'd buy one and see how we got on. Now the key thing to know is how this works. So it's not just a case of shoving things in and seeing, you know, just letting it get on with it. There's some very deliberate design involved here and there's flows. So we need to think about a flow and flow goes, there's two different flows, different directions. So if we take the lid off, obviously the compost, the food waste goes in the top and that makes its way down gradually over time. And eventually we access it by taking this front panel off here. That's the door, we'll do that in a moment. And so over time the material is going down, it's going down under gravity. Now there's another important flow which helps to keep this aerobic because the difference between anaerobic and aerobic is that anaerobic smells bad, aerobic smells nice like soil should. And so we want to keep this aerobic and the way this works is that because this is an insulated bin which allows it to be smaller than a normal compost heap because it's able to retain more of the heat that's being generated because this compost is being broken down. The food waste is decomposed initially and primarily by bacteria and through that process the bacteria generate heat and by keeping the heat in that increases the heat of the material. Obviously that's why I'm putting the lid back on again. And as it gets hotter then more bacteria become active and different kinds of bacteria kick in to the point where we could be up to 70 degrees centigrade and still have a really good process there. And then what happens over time is that that gets hotter and that goes down and in order to keep it aerobic you need a flow of air and now this is obviously very well insulated. Where does the air come from? Well it comes from the bottom here. This vent is designed to allow air through and because this is generating heat that warming air is gradually rising because warm air rises and we open this tiny little vent on the top here just a millimeter or two and that allows that warm air to escape and draw fresh cool air in from underneath. So that's the general physics. And so what goes in has to work in terms of allowing that air to flow up and not to become too stodgy. So that's all about the recipe. So the recipe is that when we put our food waste in so here's a caddy that we have at the moment. So there's a caddy of food waste and you'll notice there's a little bit of shredded paper in the bottom there and also to say not great to do on a windy day like today but this is the day I've got to make the video. So that goes in and in order to allow a good flow we also have a couple of other ingredients. So one of them is some bark chippings and the bark chippings this could just be stuff that you buy or you might have access to it from somewhere nearby I would normally put a bit more than that in with one caddy but the idea of this is that it doesn't break down because this is quite hard carbon lignin that doesn't break down quickly so that retains its structure all the way through so when we take the bottom door off and we see what's in there there's still quite a lot of this in it and the purpose of that is not to break down and become part of the compost but to stop the whole thing from becoming too stodgy and create some airflow pathways up and through and then the other thing we'll add there is some shredded paper now I tend to put in half a bin's worth but because this is really good to have in the bottom of a compost bin for the batch I would measure half one of these bins or caddies and then put most of it in just leave a little bit in the bottom for this next batch to soak up any moisture that there is in the compost and then we have a stirrer which is obviously from, they give you this it's obviously from a roller for putting paint on or something but it's perfect because it has this sort of hooking thing on the end and you can just stir this up loosely you don't want to be stirring much more deeply than just this top layer that you've put on just to mix that up a little bit like that and that's fine and you'll see at the moment perhaps you'll see that there's quite a few worms compost worms that are active and busy up here and lots of little eggs and so on it's that time of year so it's March now hot bin is the design is to generate heat or to retain heat from the bacteria in order to get it hot because then it breaks down quickly now this does come with what's called a sort of hot water bottle it's a plastic bottle you put hot water in it and then you put it inside in order to generate some heat to get the bacteria going we did that when we first got one we haven't done it since I'm much more in favour of just going with the seas nor changes in the bin so what happens what you'll see when you work with one of these is that obviously what's going in on the top is quite, well it's the temperature it comes out the caddy but as it starts to descend through the system it becomes warmer because it's getting a bit more insulation on top from the new material that's going in and it's starting to break down and so this gets hotter and hotter and then as it's broken down it then cools down so when you get to the bottom here this is warm but it's not hot down here so you have this temperature gradient so it's quite warm here then the hot bit is in the middle and then you get cooler on top now in the summer months when it's really hot the worms can't tolerate the heat in the middle here so they just hang out in the bottom and they do their thing and that's where they like to be and this heat is generated by bacteria but it breaks down very quickly which is reflected to some degree by the little thermometer that's in the lid here but if you look at the thermometer probe it's only here so all it's doing is measuring the temperature of the air directly above just in the top of the bin there so that's not an accurate representation of the heat inside so the bin comes with another little thermometer you can put in or if you've got a long compost one you can go further and that will help you to also notice the difference in temperature as you go down through so we're coming into the spring it's been quite cool over the winter but that's fine we don't really have many visitors this time of year there's only the two of us this by the way is the big, the large size bin of the two you can buy a smaller one as well a bit more compact but we find this works well for us we have quite a lot of visitors in the summer months so more than just two people's worth of material goes in here and it gets good and hot it gets good and hot but as we're coming out of winter and into spring what we do is to add a little bit of grass cutting it's just a kind of time of year when we're starting to need to mow the bits of grass around the place and you don't need very much but a little bit of fresh grass cuttings just sort of sprinkles throughout mixed in a little bit lots of nitrogen really gets it going it's amazing so in terms of what we get from this primarily it was about dealing with the compost in a safe way that gave us compost at the end and that comes out of here and whilst I thought initially we would have compost that would be able to go straight onto beds because of the bark because of the recipe we end up using it mostly around trees and shrubs but it's great stuff and it generates quite a lot and we're looking at a moment when we take the door off digging it out but the other two things that we get which were less expected is a liquid that comes out at the bottom here and you'll see that we keep a container there because it comes with a cap that you can screw on and the idea is you unscrew the cap and then you just pour it out and one of the challenges with this is this is right at the bottom of the bin so we've raised this up on a few bricks and a slab to get it a little bit higher it's still probably a little bit lower than we would want it but at the same time we also want to be able to reach to put things in the top of the bin so we couldn't lift it too high you can actually buy a base from hot bin that will lift it up but if you don't really need to you can just make up something of your own so we have this liquid and we've just been storing that in this container and it's a great plant food and this one today is a little bit more dilute than usual and that's because it's been raining quite a lot overnight you can see the water being collected in here as well but we just tuck that underneath there and then that goes well if we're thinking about the placement if we just jump a little bit ahead to where would you put your bin where have we put our bin well this is the outside of the kitchen so it's on what we call a desire line a route through to the gate here so we walk past this quite regularly and then we notice what's going on so there's a tub here with an open top white inside dark liquid it's much easier for us to notice that and not have it overflow obviously the seed tray is to catch any overflows so it's a backup so we have the liquid that comes out and the other thing we get a lot of is worms particularly at this time of year and I don't know if you can see how much this door is starting to bulge out because that would normally be flush this has got straps to hold it on around the side here as well it's starting to bulge and that's just the pressure of material inside but also there's a lot of worms in here if I lift up this it might be a bit messy whoops you can see how many worms there are underneath and they're coming out of the airhole and also through here as well so put that back on top of those for a moment protect them from the birds so yes, so place it somewhere that you'll see it also it's not too far to take out material to put it in the other thing to note is that when you've got your nice liquid feed you're going to want to not carry that too far so we found that the beds around the courtyard here are getting much more fertility they're getting fed much more often so they're much more productive as a result let's take the front off and see what it's like inside as you can see there's a lot of worms so the straps come off okay the front off and as you can see they're quite well packed in here oops a lot of worms and these are great to put in our other compost heaps because these are compost worms so that's a good addition let's put them in there your local birds are going to enjoy some of these as well it is amazing how many worms come out of here and this is obviously quite solid so this is a look by a degradable plastic not properly by a degradable it seems that was supposed to be potato starch so as you can see the material that's coming out it's still got quite a lot of bits of carbon little bits of wood and so on in it but it's perfect for going around trees and shrubs and so on and what I'll do now is I'll just finish off cutting into this one of the slight design challenges of the hot bin is that you have to sort of dig it out and by doing so of course the material on top then potentially starts to fall down although if you've got enough material in here it tends to hold itself and then once I've got enough of this out I'll put the front back on, put the straps on again and then I'll use a broom handle or something to just push down and make some holes, some air holes in the top so that it can naturally start to fall down and fill the space underneath in a way that's fairly loose and compacted. So then your next question might be how much does it cost? Well, ours was about £200 but that was three years ago and I know the price has gone up quite a bit since then that might seem like a lot of money for a compost bin and on one level it is although it does a really fantastic job of what it does and it's part of our composting system that also includes other bins so only our food waste and similar things go through here. You can make your own and there's a guy on YouTube who's got a video, a series of videos about how to build one of these this stuff is the same stuff they make car bumpers out of these days so it's quite tough even though it looks like polystyrene and it should fall apart very easily and so you could go that route what you wouldn't get with that or what you would have to work into it different aspects of the design that facilitate this flow and make it work so well you could probably fudge up a hinge for a lid quite easily but having a way of directing the liquid through from one place into one place, having air flow in these are things that might be a bit more complicated but you could be creative and that's a possibility is to do it like that so should you buy a hot bin we already did three years ago and I would definitely do it again with knowing what I know yes, it is pricey it's really good at what it does and if this is something that will meet your needs and you can afford it then I would definitely recommend buying one or if the cost seems expensive then maybe have a go at the DIY method