Tom J
Organiser: South Wales
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Registered: 8th Sep 03
Location: Bridgend
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I've got a back boiler, a hot water cylinder in the airing cupboard, and two cold water tanks in loft, one for hot water and one for heating.
The problem i have got is the shower will only give hot water at bath level, so you have to sit in the bath to have a hot shower, its a thermostatic manual mixer shower. Just wondering if there is any way i can make it so it will come out hot whilst held up on the rail or am i going to need to put an electric shower in instead? 
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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the larger of the 2 tanks in the loft needs to be lifted higher up, if you have a tank and cylinder system you really need to put a pump in for the shower, you will never get acceptable pressure from just a mixer unless its on the mains
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Tom J
Organiser: South Wales
Premium Member
Registered: 8th Sep 03
Location: Bridgend
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just want it so it will work when on the rail as moving soon anyway, how high do you think it will need to be lifted up?
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x14xe sport
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Registered: 27th Apr 09
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sounds like you'l need to have a pump fitted to the hotwater side, not a massive job but will cost you around £300 depending on pump fitted, either that or get a decent electric shower that heats the water up and runs off a cold water feed only.
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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cant put a pump just on the hot side, the hot and cold are fed from the same tank and there fore have the same pressure, you need equilibrium to work with a mixer valve, adding a pump on the hot and cold will sort the problem but as said the pump can be £300 before its even been plumbed in or wired up
the building regs state that the bottom of the tank has to be 1000mm above the shower rose in order for it to work properly
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Tom J
Organiser: South Wales
Premium Member
Registered: 8th Sep 03
Location: Bridgend
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i'll have a go raising the tank up, hopefully that will sort it 
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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The hot water is fed from the cylnder not the tanks in the loft and the cold directl from the mains. a pump on the hot to the shower would work fine.
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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the cylinder is fed from the tank in the loft
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John
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Registered: 30th Jun 03
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Cold won't be from mains either if he has a tank in the loft.
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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Time for a quick paint drawing
The Big Tank will have 2 pipes comming out of it, one will go into the bottom of the cylinder and one will go to the cold outlets in your bathroom
the cold water from the tank fills the cylinder up where it is heated by either a coil connected to a boiler or a immersion heater (or both)
because hot and cold are both fed from the same tank they both have the same pressure, the mixer valve needs equal pressures, you cant pump one side because then it wont mix.
it wont work now because the tank isnt high enough, note the pipe that comes off the top of the cylinder and goes over the top into the tank...
this is the vent, water finds its own level, that pipe only fills up to where ever the water level is in the tank, its the same with your shower, if the tank isnt high enough, it doesnt have enough pressure to force the water as high as the shower head, in tank fed systems the key factor in water pressure is how high the tank is
Im shit at explaining things in writing
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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cylinder is already full and a small pump would not drain the cylinder fast enough for there not to be enough pressure
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John
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Registered: 30th Jun 03
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Cold doesn't come from the mains though, you still need to pump both sides.
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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I know that the higher the tank the better but a pump on just the hot Would work.
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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and even if you raise the tank up so water will come out the shower head the pressure will still be piss poor, when our pump broke I had to order the one I wanted and wait a week for it, so I just bypassed the pump so I could still have a shower, while it did work it wasnt worth getting under
if you just want it to work for when you sell just raise the tank or put an electric one in, but a pump will be the best option
if you are buying a pump 2 bar is plenty enough, we have a 4 bar one and it rips the skin off your back, currently got it turned down to 2 bar
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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quote:
Originally posted by Tom J
I've got a back boiler, a hot water cylinder in the airing cupboard, and two cold water tanks in loft, one for hot water and one for heating.
The problem i have got is the shower will only give hot water at bath level, so you have to sit in the bath to have a hot shower, its a thermostatic manual mixer shower. Just wondering if there is any way i can make it so it will come out hot whilst held up on the rail or am i going to need to put an electric shower in instead?
Meaning the cold pressure is fine!
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mattk
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Registered: 27th Feb 06
Location: St. Helens
User status: Offline
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you cant pump one side of a mixer, they need equal pressure
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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Even though currently the pressures are not equal?
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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well if they arnt equal and it isnt working doesnt that prove me right of saying it has to be equal to work?
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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No because that's not the reason it doesn't work. What happens when its a mixer on a combi system when the hot pressure is lower than the cold pressure?
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John
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Registered: 30th Jun 03
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Combis give mains pressure hot water.
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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No mate they don't.
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deanmcreynolds26
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Registered: 15th Sep 03
Location: E46 //M3
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quote:
Originally posted by Rickavo
No mate they don't.
how does a combi not give mains pressure hot water? it is not by any means pumped at all,
heating is pumped, primary water is pumped through the secondary plate exchanger but it is mains water that comes through the taps on a combi boiler,
and also the only time when u will have mains water into the cylinder with not tank in loft is an unvented cylinder
[Edited on 22-10-2009 by deanmcreynolds26]
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John
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Registered: 30th Jun 03
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I must have imagined the shower I had just after posting that last night at mains pressure, from a combi 
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deanmcreynolds26
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Registered: 15th Sep 03
Location: E46 //M3
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quote:
Originally posted by John
I must have imagined the shower I had just after posting that last night at mains pressure, from a combi
ehh lol
combis do run mains pressure water mate, not pumped... uve confused me
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John
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Registered: 30th Jun 03
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I know, was aimed at the rickster there, he must be a plumber.
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