It is important that the hot pipe entering the pump is connected to something. It sounds like your plumber has just placed a length of copper pipe on show and left you to use it. Please check by placing your tougue over the end to check it is wet, or at least wetter than you.
Hope this helps
Re Tard
Re Tard, February 2011
YOUR HOT WATER PIPE IS CONNECTED WRONG CAUSING AIR TO GET TRAPPED. CONNECT IT HOW IT SHOULD BE TO THE TANK.
HI-SPEC PLUMBING, June 2006
Your pump is producing air, which normally means your pipes have a leak or there isn't enough water in your hot tank to allow the pump to flow continuously.
Check you have enough "header" to allow for the pump to work and that your hot tank is big enough to keep the pump going....also check for air gaps in your seals around the pump.
