Turbobike Web Site www.Turborick.com
Graham, I didn't find anything in Grainger, but McMaster-Carr has a couple of 12V miniature pumps that may do the trick. They're about $200 but I can't tell how heavy or big they are. The 1/100 Hp pump flows 4.3 gpm @ 1' head, with a shutoff rating of 7.1' of head. Full load amperage is 1.5 amps. There is also a 1/25 Hp model that flows 5.4 gpm @ 1'; 15' shutoff; 3.8 amps max. These pumps are rated for 250 degrees F. max., use a robust magnetic drive, and have water compatible materials throughout. I couldn't seem to download the page, but just go to www.mcmaster.com, and you'll be able find circulating pumps from there. Good Luck. Bob