ok a bit of an update from the weekend. First picture you can see I've added foam to the back beween the condensing and evaporation coil. I also closed off the compressor pump.
Next up the string supporting the evaporation coil was cut and the coil was then supported using several screws, 2 either side of the tub at various locations. Also you can see the other side now has foam.
and then the roof of the tardis...
As you can see here in the door I used 2 layers of foam staggered to limit air gaps between the foam. The picture was taken looking upwards.
This took up a lot of time due to the rebate/recess cut into the edge of the foam. Here you can see this piece was ready to be split more or less into half, with the top bit to fit in at the top of the door
and the fully enclosed tardis. I added some aluminium foil to the front door panels which does three things. 1) makes it more aesthetically pleasing with it's *ahem* shinyness
2) it seals any airgaps between the foam layers 3) helps to hold the foam in place.
Notice the ATC-800 on the floor. I unplugged the fridge thermostat and noticed it works like a simple switch. I.e when closed the fridge is on, when open the fridge is off. Simple really. So this meant to use the ATC-800 it was a simple case of bridging the live and switched live that used to go to the thermostat. Then plugging the fridge power into the cooling circuit off the ATC-800. I set this to 5'C as the air temp was around 12'C (and it's the lowest the ATC-800 can go. PS - I've got a ATC-800+ waiting in a box ready to swap it over (with a quick re-wire))
I also threw in my "lucky-reptile TR-1 thermo data logger" to record the temp over 8 ish hours.
The next morning I went to recover the datalogger. Here you can see what I was expecting...condensation from the air inside had frozen onto the coils (remember the ice crystals in one of the earlier photos from the test run)
and the resultant drops of water that had run off
So as I predicted a long time ago (see Kev's post on his fermenter fridge build IIRC) I will need to put a plastic sheet on the back wall and direct the drips downwards. I reckon then something like a piece of capped guttering with a hole in the centre and a drain pipe leading to the tray that sits on top of the compressor should work a treat.
Finally the upload of the data shows again exactly what I was expecting...
A sine type wave of heating and cooling. The max temp inside seems to rise to approx 6.2'C and down to 3.6 but the air average is 4.9'C (compared to the 5'C set point of the ATC-800)
As you can see this is fine apart from when I connect up the heater the overshoot, i.e. when the temp goes below 4'C would cause the heater to kick in. So to prevent this a simple damping to cause a small lag/stabilisation of the temp is required. i.e. either lagging the temperature probe or sticking it in a small volume of water is required. I'll do this sometime in the future to show the difference.
It's also interesting to notice the peak to trough (cooling period) to the peak to peak (full cycle of cooling followed by natural rise in temperature). The fridge seems to run for about 9 minutes each time it cools all through the night - fairly consistent as expected.
In terms of the temp rising back towards the normal air temp before the cooler kicks back in it starts off at about 9 minute intervals and gradually ends up at about 30 min intervals. This could be that the fridge over the night has cooled all of the internal objects (foam/wood etc) so by later in the morning it has less to cool, and thus stays cooler for longer. It could also be that the external temperature has dropped throughout the night (but I couldn't measure this :' )
The aim of the game is to try and extend this rise to take as long as possible - as this would mean the fridge has to come on less often to save energy. The cause of the rise is obviously heat gain (or cool air loss!) to the outside. So more insulation might be the key to fixing this. Obviously in reality No loss is optimal, but there will be loss to the conical and its contents whilst cooling and during the most active period of fermentation to keep the wort at the correct temperature which is acceptable.
admittidly I didn't insulate the floor during the test run (I am still walking around inside it to fit other bits like the heater etc) and I need to aluminium tape all the joints. I reckon this will make a big difference, but I am considering adding a second layer of insulation (seeing as I have it spare
). Funnily enough when stood inside it gets warm very rapidly as my body heat warms the small amount of air and the foil part of the kingspan reflects the infra-red heat back to me.
Jeesh - I better stop wittering on. More to follow in the future
(when I win the lottery)
