The UK and Ireland are the only countries in Europe in which a majority of homes have gravity systems. Perhaps its not surprising that our needs are not reflected in shower mixers sold for the rest of Europe but these very same mixers are offered for sale in the UK.
If you have a high pressure mains feed to both hot and cold then an efficient shower mixer will always give you a better shower than one designed for high pressure only.
If you have a gravity fed shower mixer then as well as the shower mixer looking good there are 2 key criteria which need to be considered before buying.
1.0 What is the minimum pressure requirement stated by the manufacturer
2.0 Does the mixer need balance hot and cold pressures
Mixer valves mix hot and cold water to give you the right temperature for your shower. Many mixer valves can easily balance hot and cold water pressures in the ratio of 4 to 1 – others are not very good at dealing with differential pressure, and these will also allow temperatures to fluctuate widely when someone turn a tap on or off elsewhere.
Buying a cheap mixer tap is not necessarily a problem because some of the more expensive brands give the worst performance.
The selling point ‘ideal for combi boilers’ is a strong indication that it only works on mains pressure.
Be very aware that some manufacturers sell mixers ‘suitable for gravity systems’ but without stating a minimum head this means nothing.
Be very aware that some plumbers swear that you cannot buy mixers that need only 1 metre head despite there being many mixers that only need 1 metre head.
There are many mixer valves which need only 0.1 bar pressure although because specifications are always changing we are unable to recommend a specific model.
Mira is a company that prided itself on mixers that only needed 1 metre head and some of their mixers are still very suitable. Many brands also sell mixers which will be ok but you must ask.