Hi

I found myself in a similar situation when I wanted to change from
Nationals to Modified Commercials and wasn't too keen on cutting combs
and fixing them to new frames.  Fortunately for me the only major
difference in the external dimensions of the two brood chambers was the
increased height of the Commercials.

I found a couple of articles in a booklet called Beekeeping in a
Nutshell, Manipulations by Matthew Allan (I think it's available through
the British Beekeepers Association), which worked for me:-

The two relevant chapters were "Getting Bees into New Brood Boxes" and
"Changing to a different type of brood box".

If you want a word for word copy of the text I will gladly mail it to
you directly, however the abbreviated version is:

a) Put the new Dadant brood box on top of the old National brood box, as
the boxes are of differing dimensions you will need to block the gaps (I
did something similar with a Nuc on top of a Commercial brood chamber by
using a thin sheet of Plywood, cutting a large square hole(slightly
smaller than the Nuc) in the middle of it to allow the bees access to
the two chambers).

b)  Let the bees work up into the Dadant top box.  If this is filled
with foundation, syrup feeds will speed up the process of comb building.

c)  When the queen is laying in the Dadant top box then the queen has to
be found, a queen excluder inserted between the two boxes and the queen
put for sure in the top box.

d)  24 days later, all the brood in the National bottom box will have
emerged.  There is unlikely to be much honey left in the frames, so the
National and excluder can be removed, leaving the colony in the new
frames in the Dadant box.

Good luck whichever method you choose.


Regards


Tony Bloor

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