For the past few years I've been very intrigued about these MicroCHP boilers
that are under development, for example I can see that the so-called "BAXI
Ecogen"
should be coming to market next year:

http://www.baxi.co.uk/baxiecogen

Have any uk.d-i-y ers encountered this technology yet? There must be
hundreds of these on test out there in the field.

I'm especially interested in the noise performance. Surely these things
must produce some kind of 50/100Hz Hum!!!!!!! That would drive me nuts.