On Fri, 02 Apr 2004 00:47:41 +0100, John Rumm wrote:

Dave Plowman wrote:

'Zone valves, etc' require a basic understanding of electricity to
install. Guess why our resident 'expert' doesn't like them...

It is interesting to watch in a way, but he seems to live in a world
totally governed by "rules of thumb". If he does not have one to hand
for the topic, then he will just grab one from the nearest web page, and
then cling to it for all he is worth, even when clearly it's way beyond
reason. I suppose it might be a result of a complete lack of analytical
/ scientific reason, or perhaps even a lack of basic mathematical
ability. Hence a rule of thumb is a simple way to overcome some of these
limitations that does not require taxing thought, vis:

Not able work out the actual pipe sizes required for your gas feed based
on flow resistances and pressure drops? apply rule "Install 22mm direct
to meter"

Don`t understand heat loss calcs? apply rule "you need 400mm of
insulation and tin foil under your tiles".



I think you are probably onto to something. This might account in a
bizarre way why many of us find ourselves exhorted to do things a certain
way (regardless of economics, customer expectations, practicalities, the
laws of physics, ...), whilst we are told that design calculations should
be left to 'experts'.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html