Hottop roasting tips and tricks for older model hottop

UNM

I have an older model KN 8828D hottop roaster - the one with the digital display, but limited control (basically you set how long you want it to run) as it is originally configured.

Although it is possible to roast good coffee in these, there are a few hoops to jump through to work around the machines constraints and the easiest way is to have it modified to give more manual control. I shall go into detail on some of the ways to do that in a further post. Thanks to Beanflying for much of this information

The way the standard model behaves is to turn the fan on shortly after it beeps to request loading of beans (this removes moisture), then heat is applied in varying amounts through the roast, with the fan coming on again once the hottop temp sensor detects temps above about 180C. When time is almost up, it is possible to extend the roast time and the beans can be ejected at any point durign the roast.

Trouble is, often the heater element is not at full power when you need it and then often comes on full blast between first and second crack, just when you want it to slacken off. A smaller batch of beans than maximum helps here - no more than 200 grams.

To shorten the roast time, pre warm the roaster for 10 minutes, then use manual eject  and restart to put it in cool down mode. Once it reaches a set temperature, it will start warming and beep to request loading of beans. Wait a further 1 min 30 sec to 2 min and add beans. This gets roaster fully warmed and at a good start temperature.

Press the temperature button to check temperature at intervals during the roast.

Once beans get close to first crack (after a few roasts you will know what temperature this is), lift the rear fan filter  and partially remove the cover for the bean chute - this improves airflow and you can also use a piece of card or plastic to briskly waft air across the top filter further increasing the draft. The goal of this is to reduce temperature rise between first and second crack.


Note - the temperature shown by the hottop is neither bean temp, nor environment temp, but somewhere between the two due to the location of the sensor. It is therefore not an accurate guide to what is happening with the beans if comparign to other roasters, but is useful once you know how your own roaster behaves.

derrilex

Excellent. Thanks UNM & BF. Time to fire it up

derrilex

First roast using new method. First crack at 16.30, opened the top and filter and waved the latest copy of bean scene like a madman across the top. First snaps of 2nd crack just under 2 mins later then pulled. As AM mentioned yesterday the beans are old ish. There is a bit of chaff sticking to some beans ? They are Peru ceja de selva estate

UNM

That is about  the best I managed with the unmodified hottop. I only did a couple of roasts this way. Should give a perfectly drinkable cup after resting a while. The next step for me was to add insulation between the outer casing and the roasting drum on the side where the bean mass sits (directly opposite the heater element). Many types of insulation can be used, but I spotted a silicone pot holder that was perfect for the job. It was a square waffle pattern one and fit the gap between drum and casing perfectly. I shall see if they arv still in stock at The Reject Shop and post a photo if so. This helps retain heat in the bean mass, so when trying to slow the roast between first and second can be an issue if the heater is still on full  (which led to the next mod I shall post later today). I also reduced heat loss from the top during early stages of the roast by covering it with a cloth (DANGEROUS)

derrilex

Looks like a cool mod. Pity it doesn't increase the batch size  :rofl: