I wonder if the heat loss from the lower oven (into the upper one) might cause difficulty for the energy efficiency regulations. Or on the other hand, it might be the case that the heat loss from one oven to another is much like it used to be, but better thermal insulation around the pair of ovens means that the same amount of heat finds it much more difficult to escape from the second oven, so produces a far greater temperature rise.

    - Andy.

Makes sense to me.

In the days of freestanding cookers, the grill cavity was ideal for warming plates when the oven was on.

On the basis that nobody is going to want an oven at less than 100 deg C, I don't really see a problem, but the heat conservation is poor.

Makes sense to me.

In the days of freestanding cookers, the grill cavity was ideal for warming plates when the oven was on.

On the basis that nobody is going to want an oven at less than 100 deg C, I don't really see a problem, but the heat conservation is poor.

Chris the big issue is that any unsuspecting person can get burnt at much lower temperatures, but at 100C the from door to the oven is above 40C and that is an issue for a child.

Oven doors get hot.

What age of child are you thinking of?

A toddler who is just about walking will put his or her hands against a wall in order to climb up it. If that wall is an oven door, there will be trouble. The toddler cannot withdraw because the hands are providing the support, so the palms get burned. Not nice so mothers (and fathers) have to be very careful in the kitchen.

All that said, why is the heat in the upper oven a problem? I see no reason why the two ovens should be insulated from each other.

Is there a hidden agenda here?

Chris - you ask the question " why is the heat in the upper oven a problem?" - the problem is that in a proper heat efficient oven with proper thermal insulation between the ovens -  it should not be there at all.

That is unrealistic.

Of course one could improve the insulation, but then the ovens' capacity would be much reduced. How would that suit you?

Clearly total thermal isolation is unrealistic- 'perfect'  insulation  would also suggest no oven power was needed to maintain an infinite temperature, and as cooling down is as much an essential part of cooking as warming up, there has to be heat loss and so both boxes are coupled to the outside world, and indirectly to each other !
The question we should be asking is how much temperature offset in the 'empty' oven acceptable, and that is related to how much heat transfer causes how much temperature rise, and the equilibrium between heat entering and leaving. 
Meantimes informal thermocouple tests chez MAPJ1 have indicated that our small oven above the main one reaches 80-90 C when the lower oven is used at gas mark 6 for ~ 30 mins for an instrumented meal of fish and chips. It also shows that neither compartment has reached thermal equilibrium over that timescale, the upper unused one was still getting hotter and the lower one was more or less exponentially approaching a plateau. Also there is about 20 degrees slope between the top and bottom of the oven. ~200c at the bottom, ~220C at the top. Testing was truncated after 35 minutes due to dinner being ready and there was a 5 mins or so intermission to experiments when the peas boiled over and had to be mopped up..
I think there is an element of measuring walnuts with a micrometer about this - a different very accurate but largely meaningless result each time.

I also think your oven is actually not that different in behaviour to mine, and may not be as unusual as you think.

Mike.