I am sure the image is exhaustively tested but my experience of downloading from
http://files.openenergymonitor.org/emonSD-03May16.img.zip
and writing to SD card using instructions in
(which I did using another Pi (my server which is a Pi3))
resulted in an SD card that, when put in the oldish Pi1 supplied by yourselves, did not boot.
I did no checks so need to go back and do that with md5 and copying the image back to the Pi3 and comparing it with the download.
Maybe also try another power supply.
Can somebody please confirm that this image works in Pi’s 1,2 and 3?