Scalding water from combi

[Chip]

On Tue, 28 Jun 2005 21:07:29 +0100,it is alleged that Martin Angove spake thusly in uk.d-i-y:

OOOH a mathematical question:-)

Area of a circle = Pi R ^2. The diameter of copper pipe is usually outside diameter, we want the internal diameter. The wall thickness is 0.5 to 1mm, taking as an average 0.75 mm, that gives a total of 1.5mm off the outside diameter.

Therefore 26.5mm, 20.5mm and 13.5mm internal diameter. Halving that for the radius: 13.25mm, 10.25mm and 6.75mm radius.

Which leads me to believe that the cross sectional areas are:

551.55, 330.06 and 143.14 sq mm, to 2 decimal places.

Multiply by 1000 mm in a metre of pipe, you end up with:

551550, 330060 and 143140 cubic millimetres (of which there are 1000 in a millilitre, or 1,000,000 per litre. Therefore 0.55155 Litres/metre in 28mm pipe 0.33006 Litres/metre in 22mm pipe and 0.14314 Litres/metre in 15mm pipe. Or in plain english, "28mm= Just over a half, 22mm= 'bout a third, and 15mm= 'bout a seventh of a litre per metre of pipe"

Sadly, I can't come up with a reliable formula that fits radiators, given the varied design etc, although I imagine if you multiplied the average thickness, (halfway between the troughs and ridges then add a bit for the un-troughed bit at top/bottom) and multiplied that by the height and length, if you worked in cm you'd get the result in ccs, aka millilitres, but this would be of 'guesstimate' accuracy (as is the pipe calculation). But probably close to workable:-)

[Martin Angove]

Since the extension was built since the DDA (partly in response to it; you should have seen the old toilets!) I would hope it complies. A similar-looking mixer tap in Screwfix claims to comply. Good point about use of facilities though, I'm not aware of anyone using the disabled loo :-)

Red and blue is rather Esperanto :)

There was once a record released called "Sosej, bîns a chips". Typical

1970s Welsh language rubbish of course, but there you go. Of course there's no "j" in the Welsh alphabet but you still get "jam" and "garej".

Hwyl!

M.

[Ed Sirett]

I would guesstimate about 10 litres/rad in normal circumstances including all pipework. This is of course a bit like those 20min/lb instruction on a joint. So if you have some long pipe runs that would not be present in a 'house shaped' installation then the estimate should go up a little.

Anyway I expect that the boiler's own expansion vessel (they must mean something else for 'expansion vessel' in the description of the preheating)is good for about 12 rads. This is probably a system where an additional vessel is called for, it might also be getting away with it by having very large pressure swings when in operation.