Everything on the earlier Kenmore systems was built by Whirlpool. The earlier systems used Whirlpool's own tubing and inlets. Because most Kenmore Central vacuums that were sold were sold either through the store or catalog they geared everything toward the do it yourselfer. Most of the connections were done with flexible hose to eliminate the use of elbows to install the system, it was easier but it reduced the airflow and over the years the hose dried out and became perforated and leaked. The original tubing size was 1 1/2", where as the standard of the industry was 2" thin wall, with the exception for VacuFlo and Black & Decker, VacuFlo used 1 13/16" tubing, they felt it was the optimal size for the best airflow and Black & Decker used 1 3/4" tubing. The earlier Kenmore attachments came in a caddy that was basically the top tool caddy of an early 1970's canister vacuum with a 25 foot wire reinforces 1 1/4" hose. When you chose the optional Power Mate it was the same Power Mate as they used on Sears Best canister with the addition of a small adapter pipe that connected into the Power Mates direct plug in connector, the adaptor had a switch on it to turn the Power Mate on and off and it had a 30 foot cord that would drape on the floor that would get plugged into the wall to power the Power Mate. The power units had to be vented outside, on the outside of the house it looked like a hood scoop from a race car, it was filled with fiber glass insulation to quiet the air as it would come out. In the late 70's to early 80's they changed over to 2" tubing and used a universal Beam type inlet, also now the hose end going into the wall was changed from 1' to 1 1/2". They came out with an electric hose in the late 70's also which has the switch on the handle end to turn the Power Mate on and off, it had a 6 foot pigtail at the inlet end to plug into a standard electrical outlet. The tool caddy became a vinyl bag with pockets for the attachments. The attachments over the years pretty much stayed the same, they were all the attachments that were used on the Sears Best canister vacuum. The unit itself was a very well designed unit, it did not use a bag nor a filter, however it had a cyclonic separator that kept the dirt in the container, the design worked well, it maintained full suction all the time because there was no filters or bags to clog, however the separator did need to be cleaned periodically to keep the lint, hair and carpet fibers from clogging it. The early inlet valves had a strip on the inside that you would press to turn the unit on and off, because of the momentary contact the power unit needed a ratcheting relay inside to keep the machine running, over the years it was changed to a set of contacts that when you opened the inlet the machine would turn on and when you closed it, it would shut off thus eliminating the ratchet relay in the system and just using a standard relay like most systems used. The later Beam type valves had 2 contacts inside and when you plugged the hose in a metal band would short the contacts, turning the system on. I hope this answers most of your questions on Kenmore Built In Vacuum Systems.
