Philco made [many] types of electric combinations...
Tom, this is partially correct. Focusing on the 27" platform, Philco-Bendix had three drying systems for their electric Duomatics:
1959 - 1966: cold water condensing, no blower, dubbed "air re-circulation"
1961 - 1966: "one pass system", forced air, via blower and exhaust, dubbed "Hi-Speed", CFU output ranging from 165-180 depending on model year
1967 only (H line): cold water condensing with blower, no exhaust, dubbed "Hi-Speed"
Between '59 and '66 the air-recirculated condensing system remained relatively the same, with the last gasp for the Duo in '67 being a full departure for Ford, going back to the Duomatic roots of the 36" models with the blower circulating air throughout the condensing process. I imagine the cry from dealers and consumers forced the hand at Philco to introduce the blower/exhaust Hi-Speed version of the Duo in '61 (CE-716 and CE-714). I'd love to try one of these out at some point.
Of the dozen or so loads I've dried in the '67 Duo, my experience would say that the blower system on the condensing platform didn't make a huge difference as a load of towels would easily take over an hour to dry, and well over 30 gallons of water consumed.
The '59 through '67 gas Duomatics used the same principle as the one pass blower set-up as their electric cousins, with the blower arrangement changing upon each major revision (59-60, 61-63, 65-67).
Ben