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police state

Original Poster:

3,397 posts

108 months

[news] 
Thursday 2nd November 2006 quote quote all
I have a flat which contains no water tanks, but instead draws its hot water from a 'communal supply' via a huge boiler in the block basement. The cold water supply is apparently direct from the mains.

The problem is that I have recently installed a 'thermostatic' shower, but the 'water jet' is useless, I have been told that I should install a shower pump, but when I mention this to the plumbing merchants, they suck their teeth and say their pumps are designed for gravity tanks. So the question is, what pump can I use to improve the 'shower jet'?.

ferg

15,242 posts

145 months

[news] 
Thursday 2nd November 2006 quote quote all
More info needed.

How is the hot fed??

What sort of pressure is there at the cold inlet?

You certainly can't fit a conventional shower pump on a cold main. The seals in the pump will not stand high static pressures. There are showers which work on a venturi process to 'draw' low pressure hot through using decent mains cold pressure. It is ppssible to boost mains pressure, but it's not a simple thing to do, or cheap.

skeggysteve

4,560 posts

105 months

[news] 
Thursday 2nd November 2006 quote quote all
Don't know if this helps but we've just had a pumped shower fitted.

Cold to pump is direct from cold tank in loft.

Hot is direct from hot tank - well via some sort of widget in the top of the tank - no idea what it does!

Apparently both the hot and the cold feed are done that way so if anyone turns a tap on, hot or cold, the pressure/temp from the shower does not alter.

All I know is that it works, very well.

police state

Original Poster:

3,397 posts

108 months

[news] 
Thursday 2nd November 2006 quote quote all
ferg said:
More info needed.

How is the hot fed??

What sort of pressure is there at the cold inlet?

You certainly can't fit a conventional shower pump on a cold main. The seals in the pump will not stand high static pressures. There are showers which work on a venturi process to 'draw' low pressure hot through using decent mains cold pressure. It is ppssible to boost mains pressure, but it's not a simple thing to do, or cheap.


Hello Ferg, (thanks for the reply)

The pressure on the cold inlets can be adjusted via 2 (bath & Kitchen) stopcocks in the flat, from a trickle to a torrent. The Hot supply is also adjustable via a stopcock, but is never a torrent.

The Hot feed comes via a huge (communal) boiler in the basement. It is always hot and generally a continual supply.

ferg

15,242 posts

145 months

[news] 
Thursday 2nd November 2006 quote quote all
OK

If you have no STORED cold water your best bet (in my rarely flawed opinion) is to look at one of the 'venturi' type showers which use mains pressure cold to boost the pressure of the hot.

Here's one:

www.trevishowers.co.uk/builtin_valves/boost_a.html

Edited by ferg on Thursday 2nd November 19:46
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MTv Dave

2,077 posts

144 months

[news] 
Friday 3rd November 2006 quote quote all
I have a shower pump, and I only have a water tank for the hot water - my water pressure upstairs is crap but with the pump it's fine.

jeff m

3,866 posts

146 months

[news] 
Friday 3rd November 2006 quote quote all
In the US we don't have a tank in the loft, in many states it would freeze in the winter.
Our water heater is mains fed so is at the same pressure as the cold.
Our water pressure is in the 45 to 60 psi range.

I'm not a plumber BTW, not even close, for a mult hole all around type shower one does need a pump here so they can be fitted w/o a tank.

There is also supply pipe size to consider. We have lawn and irrigation systems here, if you have a large system you have to increase your meter size from 1/2" to 5/8", and larger for commercial stuff I would imagine.

blueyes

4,799 posts

140 months

[news] 
Friday 3rd November 2006 quote quote all
police state said:
I have a flat which contains no water tanks, but instead draws its hot water from a 'communal supply' via a huge boiler in the block basement. The cold water supply is apparently direct from the mains.

The problem is that I have recently installed a 'thermostatic' shower, but the 'water jet' is useless, I have been told that I should install a shower pump, but when I mention this to the plumbing merchants, they suck their teeth and say their pumps are designed for gravity tanks. So the question is, what pump can I use to improve the 'shower jet'?.


I live in a 4th floor flat with the same sort of communal hot/mains cold supply. I fitted a 2bar(i think) pump without any problems and now have a decent amount of pressure in the shower.

I'll see if I can find a link to the one I bought.

ferg

15,242 posts

145 months

[news] 
Friday 3rd November 2006 quote quote all
jeff m said:
.......for a mult hole all around type shower one does need a pump here so they can be fitted w/o a tank.


Please beware of fitting a 'shower pump' on mains pressure water. With unvented hot water it IS possible to boost the cold and therefore the hot with a pressure set, but this is different.

engineerjim2

1 posts

83 months

[news] 
Wednesday 30th January 2008 quote quote all
I’ve got the same problem with a mixer tap shower I’ve just installed I’ve got lots of main cold water pressure, this is what I’m going to do.
Connect the cold outlet on the pump to the cold inlet looping with say about a meter up from the pump across and back down again at the top put a tee with a stop end nut fill it with water and put the stop in this way the cold side of the pump is circulated on itself and is not running dry so won’t wreck the pump. Then just connect the hot as normal.
If I then get the opposite problem I’ll put a flow restrictor on the hot supply and adjust to balance.
I may have to loop out the flow swich on the cold side of the pump don't know yet.

Edited by engineerjim2 on Wednesday 30th January 15:01

Ferg

15,242 posts

145 months

[news] 
Wednesday 30th January 2008 quote quote all
Why not use a single impeller pump... or take the cold side off a twin impeller? confused
Or, if the hot pressure is good enough, just put a pressure reducing valve on the cold (adjustable, of course)..?

Mattt

15,712 posts

106 months

[news] 
Wednesday 30th January 2008 quote quote all
1st post about plumbing?

Ferg

15,242 posts

145 months

[news] 
Wednesday 30th January 2008 quote quote all
Mattt said:
1st post about plumbing?
AquaHeads - Bathing Matters

minimoog

2,824 posts

107 months

[news] 
Wednesday 30th January 2008 quote quote all
Been reading up on shower pumps as I need one myself. It's illegal to fit a pump to a mains water supply (water regs) so combi boilers and other pressurised systems with mains cold are a no-no (but perhaps shouldn't need a pump anyway). Hence the sucking of teeth at the plumber's merchants?

Pumps are intended for gravity systems i.e. cold storage tank in loft, hot water in a tank in the airing cupboard.

If anyone has any experience of Techflow pumps I'd like to hear what you think btw wink


Edited by minimoog on Wednesday 30th January 19:04

jeff m

3,866 posts

146 months

[news] 
Wednesday 30th January 2008 quote quote all
minimoog said:
Been reading up on shower pumps as I need one myself. It's illegal to fit a pump to a mains water supply (water regs) so combi boilers and other pressurised systems with mains cold are a no-no (but perhaps shouldn't need a pump anyway). Hence the sucking of teeth at the plumber's merchants?

Pumps are intended for gravity systems i.e. cold storage tank in loft, hot water in a tank in the airing cupboard.

If anyone has any experience of Techflow pumps I'd like to hear what you think btw wink


Edited by minimoog on Wednesday 30th January 19:04
I'm suprised it's against regs and ilegal, I'm not questioning you, just suprised.
Most countries don't have storage tanks like UK, so most countries fit pumps to mains. Need to check flow specs for pump input of course to prevent cavitation but apart from that they work fine.

Do you think it's been made ilegal because it will expose low delivery rates by Water Cos. Or, what is the reason.
God forbid one should actually the same pressure in the the taps.



minimoog

2,824 posts

107 months

[news] 
Wednesday 30th January 2008 quote quote all
jeff m said:
Do you think it's been made ilegal because it will expose low delivery rates by Water Cos. Or, what is the reason.
Pretty much what you said I guess. Presumably it's to remove the risk of people pumping water from their houses back into the public main, or demanding more than the main can normally supply thereby robbing someone else of pressure. Or summat wobble

Also all the pumps I've looked at recently have had a max supply pressure of 1 bar. Mains pressure is usually more than this, so presumably a pump fed with mains mightn't last long.

Edited by minimoog on Wednesday 30th January 19:59

ff5317

444 posts

113 months

[news] 
Wednesday 30th January 2008 quote quote all

Ferg

15,242 posts

145 months

[news] 
Wednesday 30th January 2008 quote quote all
minimoog said:
Also all the pumps I've looked at recently have had a max supply pressure of 1 bar.
Earlier in the thread Ferg said:
You certainly can't fit a conventional shower pump on a cold main. The seals in the pump will not stand high static pressures. .... It is possible to boost mains pressure, but it's not a simple thing to do, or cheap.
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