New Mixer Shower with two Heads but no water!

[peterb20]

Hi all!

I have just installed a new mixer shower in my house. It has a twin outlet, one at waist height for the normal shower head, and another above head height for the fixed head outlet.

I have a mixed system (gravity hot, mains cold). The pressure from the mains is very good, the pressure in the basin next to the shower is ample.

My problem is I get literally a dribble from the waist height outlet and nothing at all from the head height. I know people are going to say the hot water needs a pump on it to boost the flow, but I dont really understand this: The outlet is approx the same height as the basin taps which has a pretty good flow rate. And in any case shouldnt the water be shooting out of the outlets, just mostly cold (ie mains fed) water? The shower mixer ive bought states that it can be used with any water system.

Any info or suggestions would be appreciated!!

Peterb

 

[flameport]

I have a mixed system (gravity hot, mains cold).

You can't use a mixer shower with that.
It has to be gravity hot & cold, or mains hot & cold, or pumped hot & cold.
Any imbalance in pressure between the two water supplies will cause it to work incorrectly or not at all.

 

[peterb20]

So what would be the (easiest/most inexpensive) solution? I am yet to bond and tile over the mixer so its not too late to change the mixer. Im a little peeved that the manufacturer states "all water systems"!

Could I add a pump to the hot outlet from the cylinder so its pressure matches that of the mains? Or do both supplies need to be pumped?

 

[Classic40]

You may get away using a pressure equalising valve but you will need to pump the gravity hot. It works better with a low pressure mixer valve, the problem is most tend to be medium/high pressure.

 

[peterb20]

The header tank for the cylinder is on a shelf immediately above the cylinder. It could be moved another metre upwards by putting it in the loft. What effect would this have on the pressure of the system? enough to make a difference?
(the shower pressure ratings are 1bar min 6bar max)

Also am i right in presuming the thermostatic valve regulates the pressure difference between the two feeds rather than the temperature, which explains why they are both being regulated to f*** all?!

 

[JimCrow]

The header tank for the cylinder is on a shelf immediately above the cylinder. It could be moved another metre upwards by putting it in the loft. What effect would this have on the pressure of the system? enough to make a difference?
(the shower pressure ratings are 1bar min 6bar max)

Also am i right in presuming the thermostatic valve regulates the pressure difference between the two feeds rather than the temperature, which explains why they are both being regulated to f*** all?!

1 Bar = 10Metres head, you have the wrong shower valve.

 

[Madrab]

Yup, you have what is classed as a medium pressure shower, what you have, on the hot, is a low pressure hot feed. Chances are it'll never work properly, as flame suggests. The thermostat feeds in the hot till it reaches the set temp then blends in the cold to keep it there, you have next to no pressure from the hot so the thermostat will not work correctly.

You need to change your cold feed 'from the mains' to 'from the cistern' and then pump them both through to the thermostatic mixer. Only way you'll get a decent shower in your current setup.

 

[peterb20]

Ok, thanks all.

Im seriously contemplating going all 21st century and getting rid of the system altogether and getting a combi fitted. Surely not that much work if the pipeworks already in! take the old out, put the new in, make the tank/cylinder redundant. Easy!

 

[JimCrow]

or one of these chaps,
http://www.screwfix.com/p/bristan-a...ancing-thermostatic-mixer-shower-chrome/13772

 

[Madrab]

or one of these chaps,
http://www.screwfix.com/p/bristan-a...ancing-thermostatic-mixer-shower-chrome/13772

Or a shower that'll work at 0.1 bar low pressure...ideal

Aint no power shower at 6.7L/min but still a shower

 

[peterb20]

wont the thermostatic valve on these showers kick in and limit the flow rate to the trickle im currently getting though! (unless im misunderstanding and i CAN put a pump on just the hot feed?)

 

[flameport]

Im seriously contemplating going all 21st century and getting rid of the system altogether and getting a combi

Combi boilers are 1970s technology.

The cheapest option is a twin pump for both hot and cold to the shower, cold being added from the cold water tank

 

[Madrab]

Not when the valve has a low limit of 0.1bar. That being said if your cold water cistern is just above the hot cylinder in your hall cupboard, you may not even be getting 0.1 bar. 0.1bar is when the cold cistern is at least 1m above the shower head.