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Old 02-19-2010, 03:17 AM   #1
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Low hot pressure to power shower


Last year I installed a shower cubicle. The water pressure wasn't sufficient for the new unit so I fitted a pump which has been fine for a year. Now I seem to have lost a lot of pressure on the hot feed to the shower. If I set the valve to cold i can hear the pump driving hard, however, switching the v/v to hot the pump either runs very lightly or comes to a halt.

I have a boiler supplying a hot water storage cylinder with an F&E tank above in the attic.

At first I had wondered if the particularly cold weather was affecting the supply of sufficient hot water but that can't be the case with a storage cylinder. I am also starting to think that it can't relly be asupply issue as the pump should still run on opening the valve but I would expect supply to be intermittent if the feed was not sufficient. These are my suspicions but I am a novice on plumbing.

My final thoughts were perhaps a blockage in the pump or pipes to the shower. I cant recall having filters in the fittings for the feed to the pump.

Any ideas folks?


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Old 02-21-2010, 04:52 AM   #2
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I still need help if anyone can?


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Old 02-21-2010, 09:35 AM   #3
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The expansion tank may be saturated i.e. have lost all of its air cushion inside. An expansion tank should be somewhere between the pump and the faucets.

Although there are more precise ways of calibrating it, the tank can usually be emptied with the water turned off, the air valve closed, and the water turned back on to achieve reasonable performance. If the tank does not have a bladder or has a damaged bladder, recalibrate it every few months since the water will absorb the air little by little.

A water pump is not supposed to go on the instant you turn on the water and go off the instant you turn off the water. Should it do so regularly, your expansion tank needs calibration.
The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 02-21-2010 at 09:44 AM.
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