HotBin refurbishment

At the end of last year I found that my Hotbin was not working as well as before - it seemed to have stopped getting up to the 60 C zone despite my feeding it with compostables as before. I dug out the bottom compost and refilled it but it just did not seem to be working as well and would not go above 40 C any more.


 


I chatted to Tony Callaghan at HotBin and he suggested my Hotbin may have "stalled" - an unusual situation only experienced in bins which had been working correctly but had then stopped getting up to 60 C.

He suggested I join in a trial he was running to check out a "fix" for this very unusual situation. I was keen and so was sent a part which needed to be retrofitted to the HotBin. To do this I needed to empty out the Hotbin.


 

 It is quite easy to put the HotBin on its side.

 
 
Lots of compost in the bottom. Compostman dug it out for me and

 


I put it into buckets, waiting to be used for tomato plants.






We took out the base plate and when we looked at it, as expected the holes were clogged up and not letting water drain out or air to move up.

  The holes were plugged with a very gooey sludge like material which sat there and did not drip off.

 The base was very wet and the air mesh was blocked. This bin had definately stalled!

I gave the HotBin a good wash out

The "fix" is a length of perforated pipe, inserted through the Base plate and which sits in the corner of the Hotbin allowing more airflow through the material. Compostman made the hole and inserted the pipe.

HotBin put back togather and refilled with some compost, grass, paper and guinea pig bedding and droppings. Ambient temp was 16 C, HotBin thermometer within a hour of refill read 30C.

I also took the opportunity to have a tidy up behind the lean to and sort out the cold frames and potting area.

At the end of a hard afternoon of work it all looked much tidier.

I will update on how well the HotBin is working later in the week but it is all looking very promising so far.

I can compost anything*, in my marvelous Hot (compost) Bin!

Proof (if proof were needed) that natural fibres rapidly compost to nothing :) These were once a wool sweater and a cotton shirt before going into my HotBin; all that is left is the synthetic thread from the sweater and the lining from the buttonholes now :)

 *In case you were wondering, the title is a play on this very funny song :) Some of you may remember it used to be at the top of my home page :-) I thought it appropriate to put it up, again :-)

Disclaimer: You can't really compost anything in a compost bin, HotBin or not! Just most things (wink)

Hotbin - over winter update.

I have not used my HotBin much over the winter - I have been feeding my wormeries with the household stuff and the chicken stuff has mainly gone into the outside compost bins to keep then going - but the HotBin will be back in full action asap once the grass mowing and weeding starts.

Having said that, I have been putting enough waste in the Hot Bin to keep it ticking over and I have found that the contents stayed consistantly 10 - 15 C hotter than ambient, even though not especially very biologically active - I have seen temperatures inside of around 15 - 20 C rather than the extreme 65 C plus when the HotBin is working at maximum effect. 




I have also noticed that a lot of compost worms have found their way into my HotBin and are happily helping to convert the material inside into compost - so I will have to make sure that I empty out the contents into another compost bin before I start refilling the Hot Bin with a lot of material - I don't want to cook my precious worms at 60 C plus!

I am very happy with my HotBin and if I lived in a small garden I would have no hesitation in getting one to eat most if not all of my waste rather than using a more conventional bin.. Even with the space I have here and lots of compost bins I find it invaluable to use the HotBin to rapidly compost down large volumes of green material so I can transfer a smaller volume into a compost bin.

Hotbin update - a look inside after 90 days.

 So, another Hotbin update:-)

It is now just about three months since I last looked behind the compost hatch of the Hotbin - so I am expecting to find some lovely looking stuff when I open it up

And I was not disappointed at all. The compost is beautiful; a little on the wet side but it will soon dry out if I leave it in the barrow under cover for a day or two.

I got nearly two wheel barrows full of compost from out of the Hotbin , the hens were mad keen to get to it but I managed to shoo them away for long enough to harvest the "black gold"

once I had dug out the finished compost the top surface dropped down into the cavity.

I shall use this compost in the polytunnel to enrich my winter crops and also spread some on the veg raised beds, before I cover them over for the winter.

So, how do I feel about my HotBin, after four months? Well my overriding feeling is one of admiration for the design and the way it works so well. I am impressed at the way it has "eaten" so many refills of material (more than 3 of them a week since the start) of mainly green waste (weeds, potato haulms, grass etc) since I got it. I am impressed , if not surprised, at the temperatures I have seen and even more impressed that I can safely compost bindweed and weed seed heads and roots - nothing much is going to survive cooking in a Hotbin at above 60 C!

  

The Hotbin is easy to use. When I add new material, after a spike in temperature of around 65C on the same day, over the next couple of days the bin surface level drops down to a settled minimum and the internal temperature settles back down to around 40 - 45 C. Lots of steam emerges when you open the lid.

At this point I refill the Hotbin with more waste on the top.  Obviously as time passed over the last three months there was more material building up in the bottom of the HotBin, so I could put less and less in the top, as there was less room.

I stopped measuring all the waste I have put in, but I estimate I have put several thousand l (ish) of waste, by volume, into the HotBin over the last three months (based on my experience after four weeks, ) This has then been worked on by thermophile bacteria and then detrivores to reduce this material down to compost  at the bottom of the HotBin.


As we approach the winter and I have stopped mowing the grass I am finding it difficult to keep the bin well fed, and I may stop altogether and just let what is inside compost down. This is partly becasue I need to divert my waste peelings etc to keep the wormeries going through the winter.

In conclusion, yet again the Hotbin does exactly what it claims; makes compost in 90 days! And that chicken carcass I put in at the end of August, when I took the first sample of compost out after 30 days? No sign of it at all :-)

Hot Bin trial after 4 weeks - first sight behind the compost hatch!

Ok, so I have had the HotBin for just over four weeks. I took these photos on Day 30, first thing in the morning.

So far, I have been very impressed. The HotBin has "eaten"  many refills of material (more than 3 of them a week since the start) of mainly green waste (weeds, potato haulms, grass etc) since I got it.
 

Each time the level dropped down to a settled minimum and the internal temperature settled back down to around 40 C,   I refilled the HotBin to the top.  Obviously as time passed there was more material left in the bottom of the HotBin, so I could put less and less inside as there was less room. But I estimate I have put more than 800 l (ish) of waste, by volume, into the HotBin, which then worked to reduce this material down to coarse mulch consistency at the bottom of the HotBin. In four weeks.


By comparison, the Dalek bin has been refilled once during this period - so has taken roughly 500 l of material ( initial 330 l plus a refill of another 150 ish l)

I have had a bit of a problem with the external thermometer, but as I am getting the internal temperatures and as the material is disappearing at a rate of knots I guess I must be doing it correctly so I am not worried. HotBin are talking to me about this issue and I am getting a replacement soon.

Whenever I open the lid, there is steam and heat! As long as there is a fresh charge of waste to work on the HotBin has kept at a steady 55 - 65 C  inside - it usually takes 3 days for the temperature to drop to around 40 C - by which time the HotBin needs (and gets)  a refill.

But after four weeks the partially composted material was building up inside the HotBin, so I decided to open up the hatch and take a look, with a view to possibly removing any material which had composted enough.

I undid the two ratchet straps which help to hold the front hatch in place

having first put an old, split compost bag down to catch any material which I took out.

hatch open for the first time in 30 days!

I must admit I was surprised to see how well the material had already composted down.

Slugs on the inside of the hatch - they get everywhere!

As always my henny "helpers" appeared to see what was going on

See how much mulch grade compost has been produced! In a month! I removed 3 buckets full of material, it was rather wet and a bit coarse to use as compost just yet, but perfectly acceptable as a mulch and if put in another bin, would make good compost within another few weeks. Which is what I am going to do with it.

I did find it a little difficult to remove the material from the bottom of the bin for two reasons. I found it physically hard to get the stuff out because of the other material above it. I also was concerned about cutting into the bin itself with my spade.

The Hotbin, three quarters empty again, waiting for a refill.

Which it got, of all sorts of stuff including bindweed ( I love watching the bindweed cook and go black inside the HotBin!)

By comparison my (larger!) Dalek compost bin , filled at the same time, under the same conditions and with a mixture of the same material, had produced a very small quantity of mulch quality standard compost. But the rest of the material in the bin was not decomposed very much at all. I removed less than a quarter of a bucket of usable mulch compost in the bottom of the Dalek bin.

Now do not get me wrong, that is very good going for a Dalek compost bin, in high summer I expect to get usable mulch from one of these in around fourteen weeks - but not in four.

So - the HotBin is yet again really impressive. I put the material I removed from the bottom of the HotBin into the Dalek bin, and personally I think that is what I am most likely to use the HotBin for, as a very rapid means to process huge volumes of compostable material and convert it into a much smaller volume of mulch grade compost. This can then be either used or put into a Dalek or other compost bin to complete the process - if you want finer, more mature compost.

And by the end of my afternoon outside, the Hotbin had already reached 55 C internally. And by the next afternoon it was up to 68 C.

Truly a "Hot Bin"

HotBin trial - the first week.

 Ok, so I have had the HotBin in situ for just over a week. I took these photos on Day 9, first thing in the morning.

So far, I have been very impressed. The HotBin has "eaten" 4 refills of mainly green waste (weed, potato haulms, grass) this week. Each time the level had dropped down to about a quarter full - (about 50 L)  I refilled the HotBin to the top.  Which means the HotBin has consumed approx. about 600 ish L of waste, by volume, reducing this material down to coarse mulch ish consistency, now sitting in the bottom of the HotBin. In a week.

Even if I removed this partially composted coarse material from the bottom of the HotBin and left it to continue to compost down in the open (or in another bin!) , the HotBin would still have dealt with a staggering amount of material in a week compared with a conventional composting bin - so on throughput of material alone I am impressed.

Whenever I open the lid, there is steam and heat!

As long as there is a fresh charge of waste to work on The HotBin has kept at a steady 55 - 60 C  - it usually takes 3 days for the temperature to drop to less than 40 C - by which time the HotBin needs  a refill.

The Dalek, by comparison, has about 100 L of waste remaining in the bottom of the composter from the original 330 L of material I put into it a week ago. The temperature has dropped from a hot 65 C,  4 days ago, to a steady 30 C. This is really good work for a Dalek composter - I am impressed!  But it is time for me to refill the Dalek, so it can heat up and get going again.

I am going to transfer the partially composted material from the Hotbin into another, empty, Dalek composter - so I can continue to see exactly how much material the HotBin can eat in a week.

I am enjoying this! But then, I am Compostwoman...

HotBin Trial Day 5 and 6 - with added Dalek!

Day 5, Tues 10th July 2012

12 pm
Ambient Temp 22 C



Hotbin had to be refilled to the brim as it had slumped to less than a quarter full and the internal temp has begun to drop rapidly to  less than 40 C - so I filled it up to the top with a mixture of weeds, grass and card, with a few handfuls of wood chips as bulking agent.

Found a slight issue when I tried to close the lid - if any debris gets on the flat surface...

The lid wont shut!

Easily fixed, though - just clear the debris away :-)

Dalek has slumped by 45 cm from the initial max fill level.

Internal temp in middle of surface layer 56 C - still working on initial charge of material.

Lots of steam.


Day 6
Wed 11 July 2012


Ambient Temp 18 C

Hotbin  has begun to warm up already. Level has significantly decreased since the refill yesterday/

 


 

Internal temp using probe, as before, in middle of surface - 46 C
Lid Temp 35 C


Dalek

Internal Temp in middle of surface layer 60 C
Internal temp at edge of surface layer 50 C

 Material slumped down by 50 cm from initial fill level.
Steaming and bin feels warm to touch from outside


 

HotBin Trial Days 2, 3 and 4

Day 1 (recap) Fri 6th July 2012

HotBin filled with a mixture of week old material from an existing compost bin, fresh weeds, cut nettles, hay and guinea pig droppings and paper scraps.



The ambient temperature was 18 Celsius when I filled the bin mid afternoon on a sunny but cool period during a showery day. After less than an hour the top temperature gauge read 40 Celsius ( reading the air temperature at the top of the HotBin) and the top layer of material inside the HotBin was at 25 Celsius.

Day 2 (recap)  Sat 7th July 2012

After 24 hours it had all slumped as the the material started to decompose.

After 24 hours the top layer of material was at 40 Celsius and the lid thermometer read 50 Celsius with an ambient temperature of 20 Celsius.

According to HotBin, this is a "textbook start"


Day 3 Sun 8th July 2012


Contents now steaming gently and when opening the lid I could feel a blast of warm air on my hands,
When taking readings the ambient temperature a cool 13 Celsius  and it was dull and rainy - not very summery weather!
Lid thermometer reading 45 Celsius.
Internal thermometer ( inserted about 10 -15 cm into material same reading regardless) at 50 Celsius.

Day 4 Mon 9th July 2012

11am.
LOTS of steam on opening the lid! Material slumped even more.

Internal temp at 60 Celsius!Yay!

Ambient temp. 16 C
Lid temp 48 C
Internal temp middle of box @ 10 cm down into material 60 C

(readings taken at 1100)


At 1800 the internal temp. was 65 C in the middle, @10 cm down and the internal temp. 2 cm from the edge, @10 cm down was 62 C.

It's hotting up in there!