Topband: AC line bypass capacitors

[Roger Graves]

My 160 TX is causing RFI to one of my baseboard heater programmable thermostats (switches modes, temperature, when I transmit). The thermostat has a 2 wire connection to 240VAC in a metal receptacle box that has a third wire common ground wire. I would like to try bypassing the AC line. Can someone suggest an appropriate (safe) capacitor for this purpose, e.g. a Digi-Key or Mouser part number? Should I use one capacitor across the 240VAC or two capacitors, one from each 120VAC line to the common wire? Thanks for the help.