That alas is only half the story. Remember much of the uk was originally
piped with 1/2" bore lead incoming mains. Quite often you have decent
static pressure, but low dynamic pressure or flow rate. So stored water
killed a number of birds with one stone. Firstly it solved the flow rate
problem. Then remember that most water was heated by solid fuel -
typically a back boiler. That required gravity circulation. Finally hot
water cylinders designed for mains pressure are far more expensive and
substantial than conventional vented ones.
Loft tanks were first used in high class homes without mains water,
in order to provide running water from a well or stream with a pump.
Homes with piped water did not need or have them.
The next impetus was when we started heating water. The first fireplace
driven water heaters tended to blow up for many reasons, but one of
them was the mains water pressure inside the cast iron heating tank,
particularly when it boiled. This problem was solved with a loft tank
to reduce pressure, and to allow boiling steam to escape. This was the
origin of loft tanks in most homes.
What you might well ask is why we kept them for so long, and I don't
really have an answer for that. We had much more restrictive water
bylaws than the rest of Europe before EU harmonisation, and that may
have caused us to stick with older designs. Mains pressure hot water
cylinders and low pressure hot water storage cylinders fed with a
pressure reducing valve were both common in the rest of the EU,
whilst being effectively outlawed here. There also seemed to be more
instant water heating (geysers) which run at mains pressure, gas and
electric powered (particularly Germany), whereas a UK electricity
domestic supply is not powerful enough for this.
There are other reasons loft tanks are used. In any commercial
premises providing some type of essential service, loft tanks are
necessary to provide coverage for loss of mains water supply, without
which you end up having to send all staff home if the supply fails.
I've worked in the financial sector where this has happened in a large
24x7 datacentre, and the premises were kept open and running by having
a tanker lorry come and refill the loft tanks after a couple of days.
I don't think this was ever a consideration for homes though.
[email address is not usable -- followup in the newsgroup]
On Sun, 08 May 2011 12:39:20 +0100, Timothy Murphy
OTH a tank in the loft with a good few gallons in it is a useful
reserve should the supply fail. This thread started with an electrical
circuit developed in the time of WW2. Many a resident at that time was
still able to carry on making tea ,cooking with water from a loft tank
until the water supply was restored. Hopefully air raids won't happen
like that again but with water becoming a scarcer resource who knows
what the future may bring in the way of rationing.
I was about to pipe up* with the suggestion that that's better wrt
hygiene (legionella etc) though you obviously need a pump to supply the
house from that. And when the leccy's off as well ...
* pun unintended.
Wiring alterations were done in my parent's house in about 1957. Double pole
fusing, TRS cable and not a ring in sight. This was done by the then
electricity board, who presumably used what was required.
In 1962 I worked in an educational establishment. Some of the more modern
parts had 13A sockets, three different versions of them. Half my time was
spent making and repairing adaptors between the various systems. I dooubt if
many wold have survived (when new) my pat testing regime of later years!
It was definitely done by the North East Electricity Board, and was
definitely later than 1956. Two new circuits, one 15A socket with clock point
teed off, and one 5A socket both to a new switch fuse..... Arghh ... it was
single pole fused .. TWO circuits, two fuses.
The original lighting circuit dating from 1936 was lead covered, double pole
fused with junction boxes filled with screwits - and we never had a fire from
That's the main reason for fuses. If of the correct rating it will blow
before anything catches fire.
I had lead covered cable here when I moved in round about '75. The
stripped back ends were in poor condition - but everything still covered
by the lead sheathing perfect. If there had been enough cable to
re-terminate, it might have been as good as new for another 40 years.
*We are born naked, wet, and hungry. Then things get worse.
Dave Plowman email@example.com London SW
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