Electric shower with low mains pressure - advice please


Postby davo7 » Sun Apr 20, 2008 12:10 am

Hello folks,

I plan to replace my mains-fed electric shower. The water pressure in the area has been measured recently and is low, barely 1 bar.

Can anyone recommend an electric shower with a decent chance of working with a low pressure mains supply? Lots of people recommend Mira showers, so I was looking at the Mira Sport 9kW, which from their blurb requires a minimum 0.7 bar inlet pressure. There's a 5m run of 6mm cable (under floorboards and through hollow partition wall) to the existing 8kW shower, so hopefully it will cope with a 9kW shower.

Another option might be a shower with a built-in pump (eg. the Triton T80si 8.5kW pumped version). However this would need connecting to the mains cold water tank, and the property freeholder wasn't very co-operative when I suggested this (I own a top-floor leasehold flat, one of seven in a converted Victorian house). I've also heard that this type of shower can be noisy and give fairly poor performance. Any opinions on these pumped showers?

I was advised that the best solution would be a proper pumped system with thermostatic shower. However this would be very expensive and there could be issues with the freeholder (he can be really awkward!), eg. depending on position, the pump could be noisy for his tenants, and/or the pump's power supply might have to be from a source outside my flat's circuit.

Basically I'm after a shower that works (most of the time) - and I don't need a really hot shower or strong spray. There would normally be no other draws on the flat's water supply at the same time as the shower.

Any advice would be gratefully received - thanks in advance. :)
davo7
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Postby rosebery » Sun Apr 20, 2008 8:06 am

"I plan to replace my mains-fed electric shower. The water pressure in the area has been measured recently and is low, barely 1 bar."

Where was this measured? At the property boundary? In your flat? Out in the street? The water company has a statutory duty to maintain a minimum pressure at 1 bar per 10 metres head. If it's 3 bar at the boundarey and 1 bar in your flat then I'd be suspicious of the plumbing that was put in when the conversion was done.

"There's a 5m run of 6mm cable (under floorboards and through hollow partition wall) to the existing 8kW shower, so hopefully it will cope with a 9kW shower."

No it probably won't and need upgrading to 10mm.

"However this would need connecting to the mains cold water tank, and the property freeholder wasn't very co-operative when I suggested this (I own a top-floor leasehold flat, one of seven in a converted Victorian house)."

Here's your real minefield. Where is the boundary between his and your responsibilities? If he's not cooperative and there are parts of this work that fall under his umbrella then you've probably got a very long wait.

It almost sounds as though the sensible approach is either put up with what you have or find another flat.

Sorry if that's a bit harsh.

Cheers
rosebery
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Joined: Wed Sep 26, 2007 8:55 pm


Postby chris_on_tour2002 » Sun Apr 20, 2008 9:25 am

if the shower that you are looking at is rated to operate on 0.7bar min and you have that then it should work fine, although the flow rate may not be fantansic. though you do say that its not so important. i would check to see what the minimum rating is for your existing shower, that may well be 0.7bar too. if so, its unlikely that your new shower will give you much better than you currently have. (saying that, you are changing from an 8kw to a 9kw - have a look at the 10.8kw as well, you might find one that will operate on low mains).

the cable feeding the existing shower, if 10mm with a 30amp rcd protecting the circuit (or 45amp for some showers - check the blurb), will do fine.

if you live in the top floor flat it shouldn't be too much of a problem to feed a shower from the cold storage tank (if there is one - you would expect there to be one in a flat but you never know with some of these landlords!) but it does depend on the goodwill of the landlord to permit you to do it and give access to the roof space.

putting in a thermostatic would prove costly and maybe impractical though not necessarily impossible. if you don't have a hot water tank as well as a cold water tank you would have to put one in. you have to pump both the hot and cold from storage tanks to give even pressure from both to your shower. and the pumps can be noisy. even the supposedly quiet running pumps are still not what you would really call quiet. i have seen boxwork around pumps with soundproofing material all round yet still giving good service access. eliminates a good proportion of the sound, not all but reasonably good. location of the pump would be critical in terms of sound travel and of course access and proximity to the tanks. a lot more complex and more to think about, plus lots more kit, ergo more money!

i have no direct experience of pumped electric showers, though i have, like you, heard mixed reviews regarding their performance value. i wouldn't expect them to be much good frankly. better to get a standard electric shower, as many kilowatts as you can to work on as little pressure as you can!

from the sound of it i haven't told you anything that you don't already know, but hope its of some help anyway.

good luck!
chris_on_tour2002
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