Problem with Power Shower Hot Water Supply

[MartinWig]

Hi
The supply of hot water through the power shower in our ensuite keeps stopping. This is an intermittent fault and I think we are getting an air lock in the system.

We can force the hot water through by turning the hot water on full, this somtetimes takes a while. I'm woried this will damage the pump.

The pipe routes up from the cylinder into the loft, passing under the main tank and then down to the pump.

Any ideas? Is there an air vent that could be fitted to relase the air pressure, say at the high point in the loft? I hope someone can help, thanks. Martin

 

[Hugh Jaleak]

Where is the hot supply for the shower connected? A wrongly positioned hot connection, can cause the pump to draw air back from the vent as opposed to water from the cylinder.

 

[MartinWig]

There is a 19mm main riser that suplies the main hot water network and rises into the loft as the vent. The supply to the pump is connected about 8" below the feed from the cylinder and is 12mm.
If this is the problem is there a way of venting the pipe?

 

[mcmoby69]

the spec for the pump will give you precise instructions on how and where to fit the necessary pipes. it should also tell you how big the tank should be to stop it running out.
bear in mind a power shower will be using water from the cylinder which is replaced by the header tank in the loft, plus it will also be using water from the same header tank to achieve the correct temperature. if it isnt big enough then it will run dry.
a 1.5 bar pump will move 16litres of water per minute
a 2 bar will shift 25litres (approx)

 

[Hugh Jaleak]

Might be better connected to the cylinder with a 'Surrey Flange'. Once the pipe is full of water it shouldn't draw air in. If the pump cant get enough water from the cylinder then it'll draw the water then air back from the vent.