Trumpy,

A lot of UK (and Irish) homes have fairly primative victorian plumbing. The old standard immersion heater tank is grossly inefficient and often totally uninsulated. Also, there are plenty of houses around that didn't have any central heating at all. Thus had no central hotwater storage! (plumbing might date from the 1800s or early 1900s!) There was an attitude that until the 1960s or so central heating was considered a totally unnecessary luxury. It's partially down to the fact that the climate in the British isles, other than perhaps the north of Scotland, is quite survivable in winter with pretty woefully inadequate space heating. Also, much of the housing stock dates from a time when there was a fireplace in every room and retrofitting it is very very disruptive.

The net result is that a lot of those systems are either incapable of supplying hotwater at all or, more commonly, don't provide enough hot water to adequately keep up with showers. i.e. they'll provide enough hot water for 1 or 2 short showers and then run cold and then take over an hour to get the tank back up to temprature again. Basically they'll provide enough hot water for 1 bath!

Many homes would have been heated with open fires (fireplaces), plug-in 3KW portable electric heaters etc.

Also, pre 1960s, most homes didn't have showers. People took baths! The concept of showering really only took off in the 1970s in a truely big way. So, a lot of plumbing systems were rather incapable of supplying showers properly.

Installing an electric shower was a simple "add on" i.e. you can take a water supply from the attic tank (almost all homes had one) and power was easily routable from the attic. So, voila.. instant hot showers..

From the late 50s/early 1960s onwards, most homes built(in Ireland anyway) had central heating as standard. In Ireland, typically hydronic and heated by pressure jet gasoil/kerosine burning boilers (Fuel oil burning's generally illegal here and has been for a very long time, other than in industrial situations where emissions can be controlled / monitiored e.g. power stations). Natural gas only came to Ireland in the 80s! (There was "town gas" made from gassifying coal/oil [the oldest type of gas used for heat/light since the 1800s] and LPG via storage tank on your premsis)

So, in general from that period on you start to see systems that were more capable of providing enough hot water for showers. However, many of them continued to use the traditional copper cylinder tank for hotwater without any sort of insulation at all and the 3KW immersion element to heat it electrically if no oil/gas heating was available.

The other problem is that the hot water tanks are usually heated by a fairly primiative water-to-water heat exchanger i.e.a coil of pipes in the bottom of the cylinder. That sources its heat from the hydronic system i.e. the water flowing through the radiators.

They do have an immersion element too for electric heating, but it's usually extremely slow.

Many such systems aren't really capable of operating in summer when the radiators are not required, or if they do they're grossly inefficient.

So, lots of people would have electric showers installed as a back up or for summer use.

Things have drastically improved though, most of those hotwater tanks installed thesedays use much more efficient heat exhangers they're refered to as "rapid recovery" and generally have much large capacity and better insulation.

In general though, the UK and Ireland (perhaps to a slightly lesser extend due to the average of houses being that bit lower) have traditionally had rather crappy heating systems [Linked Image]

There's no doubt that the electric shower / point of use hot water, is vastly more efficient than a 100 year old copper tank heated indirectly by a typically very inefficent gas or oil fired boiler [Linked Image]

While all of the above may not be the primary driving factor behind new installations of electric showers, it's certainly how they caught on in the first place!

[This message has been edited by djk (edited 01-06-2007).]