12v spdt relay, with 120v coil.

I'd like to set up a small (12v 2 amp) circulation pump to engage when my engine block heater is switched on via timer. In order to do this I think I need a relay which switches on/off a 12v DC circuit but is "triggered" by 110v household (U.S) AC current. I'd like a dual throw so that as I connect one 12v supply, I can disconnect the normal voltage supply to the pump and not have to deal with any issues of feeding power back to the ignition switch and possibly damaging electronics. Does this type of relay exist? Any suggestions on a make/model? Thanks for the help

Would it work to just buy a 120v SPDT relay, and power the coil with 120, but run 12v through the common and NO/NC contacts?

If the current rating of the relay is sufficient for what you are using, then yes you can run 12volts through the Common / NO / NC

I'm thinking about thie relay: http://www.radioshack.com/product/index.jsp?productid=2049721&filterName=Type&filterValue=DPDT I realized I need to go with the DPDT for my application with one NC connecting directly to my battery to power the pump when block heater is pluged in and the other NO to make the connection between the ignition switch power supply which normally powers the pump (when ignition is on). The relay will be switching power to a small 12v motor (2 amp max). Do I need to take any precautions to avoid inductive loads created by the motor when relay switches motor off?