Air in hot and cold water system

[zubaer]

Hi There,

Can anyone help with the following:

I live on the 4th floor of a large victorian house and constantly have problems with air in the hot and cold water system. When I run the taps water may come out for a short while (if at all) and then after a few moments completely stop!!

Does anyone know of how I can remedy this problem as it only appears to be on my floor and will the solution be expensive.

Thanks,

zubaer.

 

[Onetap]

I live on the 4th floor of a large victorian house and constantly have problems with air in the hot and cold water system. When I run the taps water may come out for a short while (if at all) and then after a few moments completely stop!!

I had to investigate a similar problem about 20 years ago, involving a 4 storey Victorian house, but it only affected the hot water. Is there one hot water system serving all floors?

It was an open vented system. When the water flows from tank to cylinder to hot water cylinder outlet (where the open vent is connected) there is a pressure loss due to friction in the pipe. When you open a tap, the pressure at all points along the pipe drops. The pressure loss is greater for faster water flow, smaller pipes, for restrictions (elbows, valves, etc) and for points further along the pipe.


The problem was the bathrooms on the ground floor got a huge flow of water from all the taps, because they were 5 storeys below the tank, hence high head/pressure. The pressure loss at the open vent was so great that the pressure fell below atmospheric and it sucked air in through the open vent pipe. The simple fix would be to fit flow restrictors to the ground floor taps to reduce the flow, whilst keeping it at an acceptable level.

I don't know how this would affect the cold system. It could be other things (pipes too small, valve partially closed, etc..). It could be dissolved air, if the system is inadequately vented or if it's an unvented system. A survey would be needed by someone who knows what they're looking for.