Shower Valves Explained

Shower Valve? Eh? Read on to find all of it explained clearly (at last).

A shower valve performs two basic functions, it controls the temperature and the flow of the water in your shower.

It controls the temperature by mixing hot and cold water from your hot and cold water supplies in different proportions and generally has a single control to do this with.

It controls the flow by controlling the overall rate of flow of the water and directing that water to one or more outlets using flow controls and/or diverters. A flow control supplies water to a single outlet and can finely control the rate of flow from full off to full on. A 2-way diverter supplies water to two separate outlets by allowing switching between the two, only one can be on at a time.

Each outlet from the valve supplies water to each part of your shower that needs it. Shower valves usually have 1, 2 or 3 outlets. So with a 1 outlet shower valve you could operate, for example, an overhead shower. With a two outlet valve you could add, for example, a shower slide rail as well. and with a 3 outlet valve you could operate an overhead shower a slide rail shower and body jets.

The Four Main Kinds of Shower Valve

Twin Shower Valves - One Way
Twin shower valves have two controls. Twin one way valves can supply a single shower function, for example an overhead shower or a small shower on a slide rail but not both. One of the two controls is a temperature control the other controls the rate of flow from full on to full off.
Twin Shower Valves - Two Way
A twin two-way shower valve also has two controls. Twin two way valves can supply two different shower functions but not at the same time, that is, it enables you to switch the water from one outlet to another, for example from the overhead shower to a smaller shower on a slide rail. The valve has a temperature control just like the twin one-way valve but instead of a flow control it has a diverter which switches the water between one outlet and the other. The diverter can switch between shower functions but it can't finely control the rate of flow, each outlet is either full on or full off.
Triple Shower Valves - Two Way
A triple two way outlet supplies two shower functions/outlets. Unlike the twin two-way shower however both outlets are controlled independently so both shower functions can be on at the same time. Triple valves have three controls. On the triple two-way valve one control is a temperature control and the others are both flow controls one controlling the flow of water to one outlet and the other to the other outlet.
Triple Shower Valves - Three Way
A triple three way outlet supplies three shower functions/outlets. Again it has a single temperature control. Of the other controls one is a two way diverter which switches water flow between one of two outlets (or it can be set so that both are off) and the second is a flow control which independently controls the flow from full off to full on of another third outlet. Typically you might use such a valve for controlling a shower set up which has an overhead drencher (large shower head), a detachable hand held smaller shower head on a slide rail and a set of body jets (the body jets all being supplied via a single outlet from the valve). If body jets were plumbed into the flow control outlet on the valve and the overhead shower and slide rail into the diverter then you could have either the drencher or the slide rail shower on and you could have the body jets on at the same time, but you couldn't have the drencher and the slide rail shower on at the same time.

Concealed and Exposed Shower Valves

Concealed shower valves are ones where when the valve is fitted only the controls are on the outside of the wall but all the water outlets and pipes that connect to them are concealed inside the wall. Exposed shower valves have the outlet(s) and associated pipes (in this case usually chrome-plated) visible on the outside of the wall.

Thermostatic and Manual Shower Valves

A thermostatic shower valve is one that incorporates an anti-scalding feature which shuts off the supply of water if its temperature exceeds a factory pre-set value. The idea is to shut closed the valve before the water coming out of the shower reaches a temperature that could injure a human being. This means if someone in another part of the house turns the cold water on causing the cold water pressure to the shower valve to be reduced and the mixed water coming out of the shower to get hotter, then anyone in the shower is protected from being caused injury by the water getting too hot.

Shower Valves with Separate Diverters

You can use a shower valve along with a separate fitted diverter. Separate diverters are commonly found on traditional exposed complete kits with an overhead shower and a slide rail, two controls on a valve control the temperature and flow but a diverter connected to a chrome water feed going up the wall switches between the slide rail or the overhead shower.

Issues to Consider when Fitting a Shower Valve

Inlet Spacing and Inlet Diameter
Two of the most common problems occur when you are trying to replace an existing exposed valve that is set into a tiled wall. So you have a hot and cold outlet coming out of the wall into the body of the valve and the valve has to be replaced. The tiles are old but treasured. The old valve spacing between the inlets is 180mm (for example) and inlets are 22mm and the only exposed traditional valves you can find seem to have 150mm spacing between the inlet centres and 15mm inlets! You can't just pull the tiles off and replumb because they can't be replaced. The answer is that the Burlington valves are 22mm inlets most of the others are 15mm. But they do all seem to have 150mm inlet centres these days, please ring me and let me know if you find any that have inlet centres other than 150mm then I can help more of the people I come across with this problem. Good luck.
Minimum Water Pressure
Each valve will have a pressure rating indicating the minimum pressure that is required for optimum performance of the valve. For most valves this minimum pressure will be low, usually 0.1 to 0.5bar, however for some valves especially those with diverters this may be higher, in some cases as high as 2 bar. If you do not have sufficient water pressure to drive the shower set up you want you may have to install a water pump. If in doubt check with your plumber and/or ring use for advice.
Balanced Water Pressure
The water pressure to each of the hot and cold inlets to the valve must be approximately equal. If they are not then your plumber may have to fit a pressure reducing valve to one of the inlets in order to equalise the pressure between them.
Non Return Valves
All valves should be fitted with non return valves. Some manufacturers include these with the valves whereas others do not. If you need these your plumber can supply them, they are very low cost items. As always if you need help please do not hesitate to ring us for advice.

What can go wrong with a Shower Valve

The short answer is 'not a a lot' and what can go wrong is easily fixed, so if your valve appears to malfunction do not stress, call me on 0113 2360214 and relax (but it does help if you know the manufacturer!).
Check Everything
see above 'Issiues to Consider when Fitting a Shower Valve' - check all this is ok if it is....these are the possible problems (some are very improbable though)
Casting Fault
This is were there is an actual hole somewhere in the metal body of the valve caused by a fault during the casting process. I've had one of these from 2004 to 2013 at the time of writing and if you have this fault you will have it on day one.
Faulty Cartrdige
The cartridge is the only part if the valve that does anything - if it leaks or otherwise fails to work then it can be easily replaced, usually on warranty but if not they are not hugely expensive.
Cartridge needs Calibrating
If the valve does not allow the water to become hot enough then you need to adjust the cartridge setting. This does not affect the thermostatic part of the valve, it just adjusts the temperature range that the hot/cold handle on the valve controls. [The following description will work on some valve, but not all.] All you need to do this is a phillips (cross head) screwdriver and my telephone number which is 0113 2360214, give me a ring.