Archive Monthly Archives: January 2011

Induction Cooktop

January 12, 2011
Back in September we took a kitchen design class at the local community college.  One of the things the instructor, Yvonne, mentioned was to be aware of the “power-sharing” and “boost” capabilities of induction cooktops because we can easily be misled about the true maximum power of a given unit from reading promotional literature.  Apparently the underlying assumption is that an user would never use all of the burners on the cooktop at the maximum capacity all at once.  OK, so we need to be wary of the marketing material and ask the right questions to get the facts straight.

The few times we browsed around the big box stores and asked the staff about the limitations of power sharing and power boost on induction cooktops we felt that we didn’t get any satisfactory answer.  Maybe the retail clerk at big box stores lacked the knowledge or were coached to answer in a certain way.  Maybe we didn’t ask the right questions.  Maybe we were confused.  The reality may be a little bit of all of that.

Well, I think I understand induction cooktop a little better today thanks to the wealth of information at http://theinductionsite.com.  This site was recommended by Yvonne in the kitchen design class but I haven’t looked at it closely until now.  I happened to come across it recently while researching and collecting data on various kitchen appliances.  Here is one example of confusing induction cooktop specification I found –
  • The cooktop has 4 burners of different sizes (diameter) and power output 
  • The entire unit has power rating of 7.4KW at 240V
  • The 4 burners are specified as 
  1. 10″ @ 2400W/3200W
  2. 8″ @ 2200W/3000W
  3. 7″ @ 1800W/2300W
  4. 6″ @ 1200W/1500W
So I’m interpreting this to mean a 10″ diameter burner has 2400W power output that can be boosted to 3200W and so on.  Then, if you add up the first set of numbers (2400W + 2200W + 1800W + 1200W) it sums up to 7600W or 7.6KW, which is slightly more than the 7.4KW rating for the entire unit.  If you add up the higher power boost numbers (3200W + 3000W + 2300W + 1500W) then it sums up to 10,000W or 10KW and that is 2600W more than the unit is rated for.  It just doesn’t add up.  The manufacturer must have assumed that you will never use all of the burners at the maximum power output at the same time.  Incidentally, one of the reviews on Consumer Report for this particular cooktop mentioned that there was a burner cycling on/off problem and recommended readers to purchase extended warranty. Maybe this person pushed all the 4 burners to the max?
You might be wondering, “So, what do these numbers mean for the Midori Haus project?”   Well, I learned that depending on the power delivery requirements of the cooktop the kitchen may need to be rewired with wires that can carry higher loads and the house panel will need to be upgraded.  To get a really good understanding of this I encourage you to visit Induction Cooking: Kitchen Electricity 101 page at http://theinductionsite.com/.  They explain the nuts and bolts in detail I really like the water flow and water pressure analogy they use in describing basic electricity principles.
You know, I’ve been cooking on gas range for the last 20 years and like cooking with gas.  We know that induction cooktop is efficient and is better for indoor air quality.  So a happy solution is to have an induction cooktop in the kitchen and have a propane gas grill on the deck for the food we want charred.  By the way, induction cooktop delivers way more power than the gas stove.  The conversion factor for a gas burner (measured in BTU/hour) to induction burner (measured in kW) is BTU/hour = kWx 7185.  Using this conversion factor we can see that the l0″ burner in our example above that delivers 2400W or 2.4kW is equivalent to a gas burner that outputs 17,244 BTU, which is way more than what’s required in wok cooking (the most power hungry cooking) of 12,000 BTU.  For more details on the conversion factor please read the section “How Much Power Is What” in theinductionsite.com.
Right now we are leaning towards the 30″ 4 burner induction cooktop from Miele.