From: "wardy" Subject: INSTALL APOWER SHOWER Date: 15 March 2007 09:30
In the next few mounths iam going to install a POWER SHOWER COULD anybody advise me on how easy this is to do + what sort of header tanks are needed and as well where and how to connecet to the hot water cylinder thanks s ward
When you buy a good power shower it will give you all you need to know about minimum requirements etc. However, from my experience I can empty the hot water cylinder in about 6 minutes, and I have upgraded my cold water feed tank to 50 gallons. The cold feed for the power shower whould be taken DIRECTLY from the tank itself and ideally on the hot water side it should come out of a (the name escapes me) device which allows the tank to vent through one orifice while drawing water out of the hot water tank through another orifice. This device screws into the top of th cylinder. The feed to the power shower should tee as closely to the hot water tank as possible to avoid other water users in the house causing the pressure to drop at the shower take off point. The reason the above device is used is because the power shower effectively sucks then the water level of the expansion pipe will drop low enough to create air voids which will cause the pump to cavitate and reduce its pumping efficiency. Both hot and cold feed must be in 22mm pipe. Ideally the pump take off should be positioned lower than bottom of the copper cylinder (dont ask me why it says so in the book!) and the pipework should be as short as practical from the cylinder top to the shower pump. The reason for the latter is that everyone believes water boils at 100C..not so...the temperature at which water boils is dependent on its pressure, and at the inlet to a pump if the pipework is too long the vacuum created can go low enough to cause the water which comes out of the tank at circa 60C to flash to steam in the pump, causing cavitation and if left long enough mechancial damage. I had this problem with a very powerful pump, and the only solution was to turn the temperature of the copper cylinder down (in which case a hot shower lasted even less than 6 minutes) or change the pump for one not quite so powerful, which I did when the original destroyed itself due to the cavitation.
By the way.... one of the best things I did was to instal a base exchange water softener (one which needs salt to regenerate), since this keeps everything very clean and feels great under the shower head.
Best of luck.