hi my shower used to work fine (ish) but now it doesn't. 
the system is as follows: 50 gal cold storage and there is a 1 foot head of water above the shower head. the top of the cylinder is 2 feet below the bottom of the cold tank.
the water feeds a double ended pump (via 2 gate valves) which feeds the shower which has a thermostatic regulator.
the installation has not actually been correctly installed as the 22mm supply from the cold to the cylinder has a tee into it and this feeds the cold to the pump as well as cold to the cylinder and i know the cold to the pump should have its own supply. there is a secondary error in that the hot outlet from the cylinder is not the correct fitting (it just looks like a simple flange and for a shower pump this should be an essex etc to help reduce airation).
this low head of water meant that when it all worked i needed to lower the auxiliary hand held shower attachment to get sufficient head to trip the pump into life.
the hot supply to the pump and the bathroom tap has always been a significantly lower pressure than the cold supply but as i understand it this should not be the case since they both have the same effective pressure just the hot has a slightly more convoluted route through the hot cylinder. i'm not a plumber and have on occasions wondered why the pressure difference was so great betwen hot and cold at the bathroom tap? this lower water pressure was also evident at the feeds to the shower head as well which is why the pump was installed in the first place.
any way IT ALL DID WORK TILL LAST WEEK! the water pressure coming out of the shower head was very low, the pump was working but the water was not hot. the cylinder was hot and so i assumed the pump was faulty. i switched off the pump and disconnected the shower unit leaving the 15mm plastic pipes hanging. as each of these has a valve just where the plastic pipes join the shower assembly i locked off each in turn to test the pump. both were being pressured by the pump although the hot did look much weaker. i left just the hot one open with the pump pressurising it and then opened the valve for the cold. after 3 seconds the hot reduced to a trickle which suggested that there was a restriction in the hot supply possibly from the teed off connection from the cold to the cylinder reducing the pressure into the cylinder (but then why has this just manifested itself?).
next i disconected the flexi pipes to the pump itself and checked that the in line filters were ok. then i tried swapping the cold and hot ends of the pump to ensure that both sides of the pump were ok. then i replaced the hot gate valve and IT STILL WONT WORK
is it possible that the flange on top of the cylinder may be furred up (the downstairs hot pressure does not seem to have changed even though that is also significantly lower than the cold).
any suggestions / help greatly appreciated - sorry its such an essay.
one other thing - why does the cold tank need to be so big? if the system depends simply on the head of water could you not use a little tank and rely on the mains pressure topping up a little tank. if this is possible i could get a tank in the loft (there is only a small 15inch square loft hatch)
the system is as follows: 50 gal cold storage and there is a 1 foot head of water above the shower head. the top of the cylinder is 2 feet below the bottom of the cold tank.
the water feeds a double ended pump (via 2 gate valves) which feeds the shower which has a thermostatic regulator.
the installation has not actually been correctly installed as the 22mm supply from the cold to the cylinder has a tee into it and this feeds the cold to the pump as well as cold to the cylinder and i know the cold to the pump should have its own supply. there is a secondary error in that the hot outlet from the cylinder is not the correct fitting (it just looks like a simple flange and for a shower pump this should be an essex etc to help reduce airation).
this low head of water meant that when it all worked i needed to lower the auxiliary hand held shower attachment to get sufficient head to trip the pump into life.
the hot supply to the pump and the bathroom tap has always been a significantly lower pressure than the cold supply but as i understand it this should not be the case since they both have the same effective pressure just the hot has a slightly more convoluted route through the hot cylinder. i'm not a plumber and have on occasions wondered why the pressure difference was so great betwen hot and cold at the bathroom tap? this lower water pressure was also evident at the feeds to the shower head as well which is why the pump was installed in the first place.
any way IT ALL DID WORK TILL LAST WEEK! the water pressure coming out of the shower head was very low, the pump was working but the water was not hot. the cylinder was hot and so i assumed the pump was faulty. i switched off the pump and disconnected the shower unit leaving the 15mm plastic pipes hanging. as each of these has a valve just where the plastic pipes join the shower assembly i locked off each in turn to test the pump. both were being pressured by the pump although the hot did look much weaker. i left just the hot one open with the pump pressurising it and then opened the valve for the cold. after 3 seconds the hot reduced to a trickle which suggested that there was a restriction in the hot supply possibly from the teed off connection from the cold to the cylinder reducing the pressure into the cylinder (but then why has this just manifested itself?).
next i disconected the flexi pipes to the pump itself and checked that the in line filters were ok. then i tried swapping the cold and hot ends of the pump to ensure that both sides of the pump were ok. then i replaced the hot gate valve and IT STILL WONT WORK
is it possible that the flange on top of the cylinder may be furred up (the downstairs hot pressure does not seem to have changed even though that is also significantly lower than the cold).
any suggestions / help greatly appreciated - sorry its such an essay.
one other thing - why does the cold tank need to be so big? if the system depends simply on the head of water could you not use a little tank and rely on the mains pressure topping up a little tank. if this is possible i could get a tank in the loft (there is only a small 15inch square loft hatch)
