If set at 100 degrees and staying 6 inches away with air contact you prob. will be hitting the surface at 80? guestimate but that shouldnt warp the vinyl, 100 on contact may warp, seen many PVC boards like AZAK buckle at high temps near 100 just due to ambient heat or UV from the sun hitting the surface and heating it up.
-- Edited by Maverick Contracting on Sunday 21st of October 2012 07:39:21 PM
I tell my customers that me and the soaps do the cleaning and the water does the rinsing, no need for hot water there. But I think adding hot water may aid in a gutter mix to boost it a little as it's applied straight from a pump sprayer or dip brush, but as far as ds'ing a house wash mix, I don't think it aids much in siding cleaning. At some point you just have to stop and wait for Spring.
Mike, I think it would be negligible if it was being applied ds'ing. Siding mold isn't near as hard to make disappear as roof mold, so temp isn't as much a factor anyhow.