I guess this has been asked before but I can't find a specific answer that fits! We have a shower that is fitted to our first floor ensuite. It is fed by the hot water tank which is downstairs and I think the cold water tank which is in our tiny loft space. We had a pump fitted but in order for it to kick in we have put the shower head on the floor and turn the shower on and then turn the sink hot water tap on and off repeatedly for 1 minute or so! A plumber told us we need to install a neg head pump, will this really solve our problem? Help please!!!!