Gene Cafe Dimmer Control Mod Stage 2

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This is a simple addition to stage 1 and will allow us to roast in low voltage situations without the use of a Variac and extend the useful voltage range of the Gene from around 227 Volts to 250 volts or higher.1
  • Target Cost = £20
  • Difficulty = easy
  • Time to complete = less than 20 minutes
  • Fully Reversible = yes


  • This would have all the benefits of stage 1
  • Will allow for roasting in low voltage conditions
  • Better roasting in low temperature conditions
  • The ramp up temperature of the gene can be fully controlled, and any desired roast profile achieved.
Risk Risk Assessment
Possible Damage to power PCB in gene Low-Medium, but very cheap component (£9.31) and easy to replace
Damage to Dimmer Low
Bright Blue flash and puff of smoke, ruined Gene Cafe Very Low, assuming competent installer
Risk of Electrocution Very Low, As always precautions should be taken, the roaster should be connected via an RCD and you should be competent to perform the tasks described
Use of a 230V Element Low, slightly shorter life expectancy than 240V element, power consumption needs close monitoring
Doing this project before reading and completing stage 1 High, likely to break something
Not using a Plug-In Power and Energy Monitor High, Likely to blow heating element quite quickly


Warning: a reasonable level of competence is required and no guarantee is given that these guidelines are error free, you undertake all work at your own risk, we take no responsibility for anything that happens

Equipment required

  • 230V heating element
  • RTV High Temperature Sealant (optional)

This project simply involves the replacement of the 240V heating element with a 230V one. The existing heater box is simply removed by loosening 2 screws and if possibly try to remove the heater box whilst leaving a flange of sealant that the new 230V box can mate up to. This may mean you can do this installation without having to reseal the box. However, you should definitely reinstall the roasting chamber and briefly run the gene (with the top cover off) and check around the joint for any hot air leaks. The leaks if left may damage the internal electrical components of your roaster. See


Ebay is a very cheap source of what looks to be suitable sealants for £5 or less delivered….so there should be no reason not to reseal your box, just ensure you use one temperature safe to around 300C. I actually found mine at a local automotive parts store for around £4 for a tube. If you check the shelves, many of these sealants are available that are safe to 250C or higher. The best thing too look for as a RTV Silicone based sealant that is temperature safe in the range 250-300C and remains flexible. Many of the high temperature gasket sealants are suitable.

The 230V heating element is actually shorter than the 240V element, which lowers the overall resistance and allows it to draw more power at lower voltages. This means that to supply the same watts as a 240V element, the shorter 230V element has to actually glow hotter (simply because it's surface area is smaller). This means that these elements will have a slightly shorter life. Had Genesis made the 230V element the same length, but thicker, then the element would have a longer life than a 240V element….but they didn't.

This project is also applicable to those in 230V countries who are having problems with low voltages and you simply have to get yourself a 220V element (if your reseller has one, I am fairly sure they are made). Depending on Genesis strategy for making these (as mentioned above), will also dictate their longevity.


Is the same as for the stage one project, except you can potentially control the ramp up far more as you can over power the Gene element, assuming your voltage is not at the bottom limit of usability. There is an element of care that will need to be taken and YOU MUST ENSURE YOUR WATTAGE DRAW DOES NOT GO ABOVE 1250W, above 1250W and you are outside the design limits of the Gene, if possible it's always best to keep to around 1180W unless it's really cold and you need 1250W to allow roasting (the cold air in will mitigate the effect of the high wattage), OK i admit, if the conditions were 3C in my Garage, I suppose I would be tempted to push 1270W, maybe even slightly higher but then if my heating element or worse broke, I only have myself to blame..

The overall cost of both a stage 1 and stage 2 project is around £40, generally much, much cheaper than a Variac (£80-100), but with the significant advantage of only having a small control box attached to the gene and it being a realistic proposition to use indoors, where a 8-10Kg variac might look a little out of place. In addition this system can do what a variac can't, and that's vary the heating element power WITHOUT affecting the drum motor speed or airflow of the Gene Cafe.

Thanks to Martin (Mole) for working with me on this project and providing the additional help needed to achieve a successful solution.