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adding anti freeze to central heating |
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| message from Bloss on 20 May 2004 |
I'm putting a radiator in my conservatory so I can use it on the odd
day in the winter so I'm going to add Fernox alphi11 antifreeze to the
system. How much do I need to add? They reommend a 25% mix, is there a
quick way to calculate the ammount of water in the system so I don't
have to drain the whole thing down.
Before anyone asks part of the system has stop valves so I don't have
to drain down to fit the new rad.
Thanks
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| Christian McArdle replied to Bloss on 20 May 2004 |
Is the conservatory on its own zone with a programmable room thermostat?
Mine will be, so won't require antifreeze, as the programmable thermostat
has frost protection. It's pretty hard to freeze burst plastic pipe, too, so
it might be an idea to plumb in that, rather than copper.
Christian.
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| Bloss replied to Christian McArdle on 25 May 2004 |
It's an open vented system and the rad will be on the same circuit as
all the rest of the rads.
I could put a frost stat in the conservatory but her indoors doesn't
like the central heating to come on in the middle of the night hence
adding anti freeze.
I will drain it down over the summer then add the anti freeze.
Thanks
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| Christian McArdle replied to Bloss on 25 May 2004 |
Fair enough. I'd still use plastic pipe in a conservatory, though.
Christian.
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| Andy Hall replied to Bloss on 20 May 2004 |
The hard way. I needed to do this for a separate circuit that I
have heating my workshop.
Find the radiator types or one close to it on a radiator
manufacturer's web site. Obviously there are various types with one
or two panels. Normally the data sheets give a water capacity in
litres per section for a given height of radiator. Count the sections
on each radiator in question and multiply out.
This will be the largest amount.
For the pipework, guesstimate and treat it as a set of cylinders.
Add up the 15mm runs and the 22mm (and other sizes) in terms of length
(two legs remember). Multiply diameter by pi and by length to
determine the volume, remembering to get the decimal point in the
right place to determine litres.
The HW cylinder and boiler together you can count as 10 litres. Add
another 5 for the header tank or pressure vessel.
As a sanity check in a typical house you will be between 50 and
150litres.
Work out the Alphi-11 on that basis. It doesn't matter too much if
you go to higher concentration than 25%. I have mine at about 35%.
.andy
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| Graeme replied to Andy Hall on 20 May 2004 |
<snip snip>
Volume of a cylinder = pi * radius^2 * length (not; pi * diam * length).
At last I've managed to contribute something to this group, instead of
always asking!
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| Andy Hall replied to Graeme on 20 May 2004 |
You're absolutely right pi x d provides the circumference.
This was the deliberate mistake to make sure that people were paying
attention.
Well that's my story and I'm sticking to it. :-)
.andy
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| BigWallop replied to Andy Hall on 20 May 2004 |
The radius squared multiplied by pi gives the area of a circle. Two times Pi
multiplied by the diameter give the circumference. Pi multiplied by 4 then multiplied
by the radius squared gives you the surface area of a sphere.
http://mathforum.org/paths/measurement/aos.html
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| Andy Hall replied to BigWallop on 20 May 2004 |
2 x pi x radius = circumference
.andy
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| Ric replied to Andy Hall on 20 May 2004 |
That would make more sense - the circumference is Pi x Diameter which is the
same as Pi x Diameter x radius, the Diameter being twice that radius.
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| Grunff replied to Andy Hall on 20 May 2004 |
Also provides the area for circles where d = r^2 - so your original
formula would work fine for pipes of 2cm diameter :-)
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| David Kerr replied to Grunff on 20 May 2004 |
Err........... don't you mean 4cm diameter?
Thus radius = 2 and radius squared = 4 = diameter
(numerically, that is)
David
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| Andy Hall replied to David Kerr on 20 May 2004 |
OK, so we're all arithmetically challenged today. :-)
.andy
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| Grunff replied to David Kerr on 20 May 2004 |
Yes! That's exactly what I mean. Or rather, I meant to say "would work
for pipes of 2cm /radius/".
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| Dave Gibson replied to Grunff on 20 May 2004 |
Or to put it another way:-
15mm tube = 7.57 metres/litre
22mm tube = 3.18 metres/litre
Dave
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| Capitol replied to Andy Hall on 20 May 2004 |
What stops the antifreeze from evaporating in an open system? Have I missed
something?
Regards
Capitol
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| Andy Hall replied to Capitol on 20 May 2004 |
I don't think that the OP has said whether his is open anyway.
I used Alphi-11 in a sealed system.
I can't find anything on the container or the Fernox web site saying
that it is not suitable for open vented systems.
.andy
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| Elessar replied to Andy Hall on 20 May 2004 |
Why not drain off a rough 25% - say 25L if Andy is right - add this amount
of antifreeze to the header tank and run the system for a few months until
it's thoroughly mixed. (It's not going to freeze over the summer...).
Then take a small sample from the drain point and put it in the fridge
ice-box or freezer.It shouldn't freeze at all in the former, and should stay
liquid or at worst slushy in the latter.
If this antifreeze is glycol- based you might also get a good idea of its
freezing point using a hygrometer designed for car radiators.
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| Andy Hall replied to Elessar on 20 May 2004 |
True, although it is worth getting it reasonably right because
Alphi-11 (which is an antifreeze and inhibitor is around £17 per
5 litres.
.andy
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Archived message: adding anti freeze to central heating (UK D-I-Y House Improvement)
