NJJoe wrote: ...a dryer when fed with hot water from a boiler on site will be limited to 212 degrees at maximum (give or take a few degrees either way). Whereas a gas or electric dryer can produce higher temps since the fuel is burned right there or electric elements are glowing locally. That should translate to higher temperatures in the dryer chamber and shorter clothes drying times than the temps from boiler water.
AFAIK modern dryers limit the operation of the heating elements so that the temperatures they produce in the air entering the drying chamber is comparable to the temperature that could be produced by a coal appliance, either directly or through a coil. On that basis, I wouldn't expect there to be a big difference in the drying times.