2 showers on same feed won't run simultaneously
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Luke J
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2 showers on same feed won't run simultaneously

by Luke J » Sun Mar 17, 2024 9:31 pm

Hi all- I am not at all proficient at plumbing but have recently swapped out a salamander shower pump after the old one died. I have another shower with its own pump. Both showers are upstairs and I have a gravity fed system. Both showers appear to use the same hot water supply pipe.

Since changing the pump I have noticed that the two showers do not seem to want to operate simultaneously. If one is already running with hot water the pump on the other one does not activate when you turn the shower on (or does so sporadically). I have noticed that if I effectively " throttle" the hot water supply to 1 pump (with the isolation valve) the other one seems to activate more effectively - so my theory is that when both showers are on there is not enough water pressure/flow in the hot water pipe (ie split between the two showers) to activate both pumps?

In case it is relevant I also noticed that the replacement pump says it is 2.1 bar whereas the old pump was 1.9 bar- might that mean that the new pump is using more of the limited hot water supply than the old pump, which I presumed might cause my problem? Having said that, even with the old pump I would sometimes find that both showers did not want to run simultaneously, or would "pulse".

If I am right that the cause is low hot water pressure, is the best solution to have a pump fitted on the hot water pipe coming out of the hot water cylinder (which is downstairs), which would presumeably increase the hot water pressure generally in the house?

Many thanks

stoneyboy
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Re: 2 showers on same feed won't run simultaneously

by stoneyboy » Mon Mar 18, 2024 11:15 pm

Hi lukej,
Yes you can fit the pump so all hot water is pump fed, the problem may be that one pump may not be able to maintain sufficient pressure if both showers are running at the same time. To explain, generally a 2 bar pump will give 2 bar if there is no flow, if the flow is 10 litres per minute the pressure will drop to 1 bar and if 20 litres per minute the pressure will be practically zero.
You may do better to look at ways of improving the flow rate out of the tank, so if both pumps are currently fed through one top tapping on the tank you could fit a Surrey flange or if there is an additional hot feed connection on the tank use this.
Regards S

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