Mixer shower to hot !!! help needed

waterloose1 · 2 Oct 2008

Hello first post,

I have a roper rhodes storm shower/mixer tap on the bath this is attached to a shower kit from screwfix via the hose from the tap, the problem i have is it gets very hot even with the cold tap full on and the hot tap only just turned on to low when i use it for a shower ?.The temperature is ok if i turn the hot and cold tap on when using the tap for the bath but as soon as i turn the knob on the tap to shower mode it gets boiling hot when it comes out of the shower ? its like as soon as the water leaves the tap goes up the hose it gets hot and no cold is getting through but as soon as i revert back to running the water into the bath its ok again any help would be much appreciated.

Is this to do with the pressure off the water i have a combi boiler and live in a block of flats if this helps.

seco services · 2 Oct 2008

i would say its a tap problem as its ok when on the taps rather than the shower.

how old is the taps ?
how long have they been like this?

weseeyou · 2 Oct 2008

if you are running the mixer off a combi boiler it sounds like you need to regulate the boiler hot water flow rate and or hot water temperature setting on the boiler. Is the mixer tap recommended for use with combi boilers ?

The shower hose doesn't flow as much water as the taps which is why the taps mixes better and runs cooler than the shower.

waterloose1 · 2 Oct 2008

Taps are brand new plus its been like this since i had the bathroom done i cannot understand why when i just use the tap for running a bath the temp is ok it seems to mix ok but as soon as i select the shower it gets boiling hot and is very dangerous i have kids how cannot use the shower now.
Its like the c/w just stops once it leaves the tap and only hot is getting through is this something to do with the pressure of the water if i turn the cold tap full on then just a little hot it gets very hot I'm lost as to what to do about it ?

waterloose1 · 2 Oct 2008

weseeyou said:
if you are running the mixer off a combi boiler it sounds like you need to regulate the boiler hot water flow rate and or hot water temperature setting on the boiler. Is the mixer tap recommended for use with combi boilers ?

The shower hose doesn't flow as much water as the taps which is why the taps mixes better and runs cooler than the shower.

I have turned the boiler down to 7 thats what the manual says for a mixer shower still the same. The tap is a roper rhodes storm mixer and it is ok for high and low pressure.

weseeyou · 2 Oct 2008

waterloose1 said:
i cannot understand why when i just use the tap for running a bath the temp is ok it seems to mix ok but as soon as i select the shower it gets boiling hot and is very dangerous?

As I said previously it is because a shower hose passes a fraction of the amount of water that your taps do.
The slower the water passes through your boiler the hotter it will be.

Try turning a kitchen hot tap on and running it for a while then reduce the flow down to half with the boiler still running and see what happens to the water temperature. basic physics

waterloose1 · 2 Oct 2008

weseeyou said:
waterloose1 said:

i cannot understand why when i just use the tap for running a bath the temp is ok it seems to mix ok but as soon as i select the shower it gets boiling hot and is very dangerous?

Click to expand...

As I said previously it is because a shower hose passes a fraction of the amount of water that your taps do.
The slower the water passes through your boiler the hotter it will be.

Try turning a kitchen hot tap on and running it for a while then reduce the flow down to half with the boiler still running and see what happens to the water temperature. basic physics

cheers

any thing to sort this out what about if i bought a thermostatic mixer/shower tap would this help or can i do anything with the existing mixer tap and shower.

weseeyou · 3 Oct 2008

yes you need a thermostatic mixer/blender. they are frequently used on hot taps in public buildings to reduce the water temperature at the tap to prevent scalding. Ask at a local plumbing suppliers like Plumbase etc

TicklyT · 3 Oct 2008

Is the cold supply to the bathroom at mains pressure or gravity fed?

If the hot and cold water pressures are not reasonably balanced, then it will be a difficult job getting any mixer to work properly.

It would not be the first time bathroom cold water supplies have been left running from a (more or less redundant) cold storage tank when a combi boiler has been installed.

waterloose1 · 3 Oct 2008

TicklyT said:
Is the cold supply to the bathroom at mains pressure or gravity fed?

If the hot and cold water pressures are not reasonably balanced, then it will be a difficult job getting any mixer to work properly.

It would not be the first time bathroom cold water supplies have been left running from a (more or less redundant) cold storage tank when a combi boiler has been installed.

Hi the cold water is mains i think as i have tried to stop the cold water flow with my thumb and its hard to stop is this the correct way of testing ?

The hot and cold water seem to come out at the same flow rate the cold even seems to be more forceful than the hot. I live in a block of flats on the 2nd floor of a 4 floor block there is a cold water tank on the roof of the building but dont know if this is being used ?
You say about the cold water from a storage tank with the combi is this wrong and have can i check.

waterloose1 · 3 Oct 2008

weseeyou said:
yes you need a thermostatic mixer/blender. they are frequently used on hot taps in public buildings to reduce the water temperature at the tap to prevent scalding. Ask at a local plumbing suppliers like Plumbase etc

Thanks i have been looking at old posts and on other internet sites and as TicklyT says a thermostatic bath mixer may not work so im i just stuck with a crap shower ? anybody else know of a way around the hot water issue please reply

seco services · 3 Oct 2008

shut your mains stopcock and see if the cold still runs.

waterloose1 · 3 Oct 2008

seco services said:
shut your mains stopcock and see if the cold still runs.

Yes i have shut the mains stopcock and the bath cold is off but the kitchen cold is working ok should the cold be coming from the combi like the kitchen taps and not the mains and is this why i have the pressure balance problem if so what can be done about this cheers.

Sorry if the above does not make any sense as i know f all about this subject.

seco services · 3 Oct 2008

the mains stopcock should shut the kitchen cold.
if you have shut the bath cold and the kitchen is still running that means they are on different feeds.
so the bath feed could still be from a tank feed.

waterloose1 · 3 Oct 2008

seco services said:
the mains stopcock should shut the kitchen cold.
if you have shut the bath cold and the kitchen is still running that means they are on different feeds.
so the bath feed could still be from a tank feed.

So if the bath feed is from the tank is this a problem.

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Mixer shower to hot !!! help needed

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