hot water only warm?

Possiblly hot water diaphragm. They're cheap enough and easy to replace. You can get one here cheap:

http://cgi.ebay.co.uk/Baxi-248838-80e-105e-HE-INSTANT-Hot-Water-Diaphragm_W0QQitemZ200287408319QQcmdZViewItemQQptZUK_Home_Garden_Hearing_Cooling_Air?hash=item200287408319&_trksid=p3286.c0.m14&_trkparms=72%3A1301|66%3A2|65%3A12|39%3A2|240%3A1318

Joe
January 2009