switching the electric also only shuts off one line. I think the manual shutoff is the better solution. besides these leak a little so it should not allow the heater core to stagnate. timer relays are expensive and wont stand up to under hood auto use, and they usually only delay up to a minute

__________________

1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)