What volume is my sealed CH system?

[Lobster]

I'm currently flushing out my CH system (as I write, trying to dislodge airlocks...! :-( ) and hopefully will be in a position to add some new inhibitor.

I'm wondering how much I need to add, in that I haven't a clue what the internal volume of my (sealed) system is. I have 15 rads/towel rails of varying sizes (with mixture of 22/15/10 mm pipework if that makes any difference) .

Any ideas as to a ballpark figure? As I'm adding Sentinel X100, which needs 1 bottle per 100 litres, I'm asking should I be adding one bottle or three?

Thanks David

[Andy Hall]

Well.....

You can calculate it:

- Radiator manufacturer web sites have data sheets where you can normally find the amount of water per section for given heights of radiator, bearing in mind single or double panel. Multiply by the number of sections.

- Make a reasonable assumption about pipe lengths. Volume is pi x diameter x length. You will find that the amount is small in comparison to radiator volume.

- Add 15 litres or so to account for HW cylinder, boiler and expansion vessel contents.

OR....

- You will almost certainly find that it's less than or about 100 litres.

OR...

- It won't be more than 200 litres, so you can put in two lots of jollop and consider that in comparison to replacing all the radiators, it is very cheap. Overdosing doesn't matter.

[Vortex]

Page 14 of the Quinn price guide gives info for calculating volume of typical rads:

my case I have about 22 linear metres of 520mm standard "round top" rads..corresponding to about 110 litres.

Plus pipework of course (+10%?)

David

[Ron Lowe]

Tsch!

Volume is Cross-Sectional area * Length.

Area of a circle is pi * r^2, or pi * d^2 / 4

Not pi * d.

So Vol = pi*d^2/4 * L. ( remember to convert units of d and L as appropriate to obtain volume in whatever units you want. )

From my old maths teacher:

"Write it out 100 times, in ink, for tomorrow. And at the same time, learn it."

[Andy Hall]

Very good. Just checking that people were paying attention......