mini one pipe from thermostat to heater

[laserman]

I have just sorted my daughters thermostat housing and the plastic connection in her mini one but made the fatal mistake of removing all the pipework to the heater.Does anyone know if the pipe from the thermostat goes to the top or the bottom of the heater.My head says it goes to the top but I don't want to have to do the job again.
Thanks for any sensible advice