worse water pressure than old electric shower

[frustrated1]

I have recently had a very expensive bathroom makeover by a local 'reputable' firm. They had recommended and fitted a power shower which proved incompatable with my water system. ~To cut a long story short after discovering this boob on their part I asked them to fit an electric shower instead. There had been an electric shower which worked perfectly well with adequate pressure installed previously.

A Mira Sport 9.8KW has been put in, but the pressure is dire, much worse than our old electric shower (an old 8.5KW). I think this poor performance is because the new shower is fed from a cold feed pipe tapped into the mains near the cold water tank in the loft. It is actually tapped into a pipe which feeds the top up tank for my central heating system which is the last take off after both my own and my downstairs neighbour's cold water tanks.

Our cold water system is all mains fed. The cold tanks are the last take off after the Kitchen through to Bathroom system, first my downstairs neighbour, then mine, then up to the tanks in the loft.

The old electric shower was fed from the cold feed to the bathroom, tapped into the supply to the bath.

I think they have tried a cheap fix instead of breaking into the pipe cavity at back of shower to access the cold feed to the bathroom, without taking into consideration the impact the extra level up into loft ( and length of run!) would have on water pressure.

There is a pipe there as originally they did not realise it was a mains vented system (which would have damaged the power shower originally installed) and put a cold feed pipe in leading from bathroom feed supply (at first floor level). This was not cut back but just capped. I now have two spare pipes in this cavity behind shower a hot and a cold both capped! The pipe in loft (second floor level) they have used to feed the electric shower was the one they originally tapped into my (much too small) cold water tank for the power shower.

Help and advice please from proper instead of mickey mouse plumbers would be greatly appreciated.

 

[Slugbabydotcom]

I think this poor performance is because the new shower is fed from a cold feed pipe tapped into the mains near the cold water tank in the loft.

Are you 100% sure they tapped into the mains

without taking into consideration the impact the extra level up into loft ( and length of run!)

Shouldn't make much difference to mains pressure!

More likely that there is a restriction in the pipe caused by fitting an isolation valve or maybe not fully opening an isolation valve.
Could be something as daft as not having opened the mains stop tap enough

Another thing is that the mains water temperature has dropped recently with the onset of winter. This means that more energy is needed to get the same amount of hot water Ok you have an extra 1.3KW but this will be more than soaked up by the extra energy demand caused by the colder water.

they did not realise it was a mains vented system (which would have damaged the power shower originally installed)

This is confusing.

If you have a mains unvented hot water system A pump could not be used and a thermostatic mixer with a balanced supply should have been fitted.
If you have a vented hot water system fed through a tank supplied by mains water then that is what shower pumps are designed for so why couldn't they fit it.
Is there something lost in the translation here perhaps? To 'vent the mains' would require a pipe that goes up at least 30metres into the air and would serve no useful purpose in providing hot water.

 

[frustrated1]

Maybe I have got the term wrong? The mains vented system is the cold water system (see what you mean about venting the mains!!) which is supplied to all cold water outlets directly from the mains. The only thing supplied by the cold water tank in the loft is the hot water cylinder (which has a coil inside it for central heating system and an expansion tank in the loft).

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The water board does state that mains pressure declines with each floor level. It also depends on the altitude of the property in comparison to the water supply ie up the hill or down the hill. Not every one's mains water pressure is good enough to push it up a hill and then up to second floor or above level leaving sufficient pressure to run a shower. Other properties in a street also compete for the supply. Second floor flats (and higher) in this area are warned that showers may give poor performance.

However, my complaint is the reduction in water pressure since the changes were made to the plumbing. This route for the cold pipe feed to the shower has also added about an extra 20 feet and several bends to the original shower set up in addition to the extra height.

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The pipe for shower could technically be said to be attached to the feed pipe for the expansion tank rather than the main cold pipe which branches into 3 - one to my cold water tank, one to my downstairs neighbour's, one to the expansion tank.

 

[Slugbabydotcom]

The water board does state that mains pressure declines with each floor level. It also depends on the altitude of the property in comparison to the water supply ie up the hill or down the hill. Not every one's mains water pressure is good enough to push it up a hill and then up to second floor or above level leaving sufficient pressure to run a shower. Other properties in a street also compete for the supply. Second floor flats (and higher) in this area are warned that showers may give poor performance.

However, my complaint is the reduction in water pressure since the changes were made to the plumbing. This route for the cold pipe feed to the shower has also added about an extra 20 feet and several bends to the original shower set up in addition to the extra height.

So the valid part of the point you are making is that of the frictional resistance caused by this extra 20' of pipe and few extra bends.
What you lose in height because the pipe runs higher you get back in pressure from the column of water above the outlet so long as the shower outlet is at the same height as it was before.
My opinion is that it will make a difference but not much of one. Perhaps someone elses opinion could differ If it does I'm sure they will add a post


Now to the bit thats still leaving me confused

The only thing supplied by the cold water tank in the loft is the hot water cylinder .

Ok I understand that bit

The pipe for shower could technically be said to be attached to the feed pipe for the expansion tank

Thats the mains going into the expansion tank ... Yes or No?

rather than the main cold pipe which branches into 3 - one to my cold water tank, one to my downstairs neighbour's, one to the expansion tank.

So it doesn't connect into the mains then! If it did this pipe would branch into 4

1 The cold tank
2 The expansion tank
3 Next door
4 The shower

This leaves the frightening possibility that your shower is connected to the expansion tank. This would explain a really poor flow as you could only have about one metre head.