Hello, I have replaced my economy 7 water heater after the elements finally packed up at about 20 years. I was unable to remove the elements without destroying the tank, so i waited till another tank came along with the elements fitted (second hand but only about 3 years old).
I piped it into the original position, more or less. The only alteration to the pipe work was made with plastic pipe not copper and that was at the top of the tank where the outlet now comes out about 6 inches upwards as this tank must be slightly shorter than the original, before going off at 90 degrees along the original pipework.
The fill seems all ok and i checked for leaks before connecting the electrics (which were tested prior to any installation by a sparky).
The water heats correctly but when we draw hot water, the flow starts ok then peters off to a trickle, coughing and spluttering.
There appears to be no restriction in any new pipework (very little as there is) and the header tank in the loft seems to fill as it ever did.
The slowing down of flow starts after about 10 seconds and if we close the tap and wait 5 seconds and turn it on again it runs ok again for another 10 seconds or so.
Sounds like an airlock in your hot water system, probably in the cylinder. Try connecting the cold and hot taps on your kitchen sink together with a hose. Then open the hot tap followed by the cold one(slowly). The mains preesure from the cold water should then push the air out of the system up into your cold water storage tank. If you have a mixer tap on the kitchen sink, simply push your thumb over the outlet and open the taps as suggested.
Alternatively, just leave your bath hot tap open and see if it will just carry on spluttering until the flow eventually restores to normal.
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