Hehe.... I no longer have the luxury of a basement in the new house, and nor does anyone I know
at the moment... however, the workshop I use over in Castleford has a painting booth that is always a fairly constant temp, and always bitter cold if no spraying has gone on recently... will have words with the relevant folks...
Heatsource.... well I could produce a staggering heatload if I needed to
just over-ride the thermostat in an electric cooker and then undervolt a ring element
should work (?) - just can't pin a figure on that heatload unless someone knows the maths to work it back from the original wattage rating of the element vs 240v pulled down to 100v...