It works like a charm. Ran the engine for about 1/2 hour to get it all warmed up. Shut off the engine. Fired up my underseat heater with the heater control still closed. Cold air. Fired up the electric pump and opened the heater control---we have HEAT! The pump works. Several people told me this would do little good to get rid of heat in the heads upon shut down because the water would only be running in the heater hoses only. I turned the key back on to get a heat reading. The temp NEVER went up like it always does. After 10 min the temp began to fall. After 30 min I fired up the underseat heater and there was still plenty of heat in the water. I like it when a plan comes together.