"Dave Liquorice" wrote in message
ll.co.uk...
Domestic CH circulator type pumps. The graphs giving flow rate use
"head" as the other axis. What head is this? Highest to lowest point
in the loop? Pump to lowest, pump to highest? Something completely
differnt like flow resistance of the entire loop?

Flow resistance related.

There is also a static head figure which will be the minimum head needed to
avoid cavitation.
There is also a maximum head before it breaks, but I don't recall seeing it
quoted on any domestic circulator.


I'd like to have a rough guesstimate as to the flow rate the load
controller on the woodburner is producing so I can get an idea of how
much energy is being transfered from the woodburners boiler to the
thermal store.

You need to workout the flow resistance of all the pipes and joints and then
lookup the flow in the table.

On Sun, 29 Jan 2012 15:28:20 -0000, dennis@home wrote:

You need to workout the flow resistance of all the pipes and joints and
then lookup the flow in the table.

Is there a nice handy look up table for 28mm copper 45 and 90 bends a
resistance per unit length of tube?

--
Cheers
Dave.

On Jan 30, 12:07*am, "Dave Liquorice"
wrote:

Is there a nice handy look up table for 28mm copper 45 and 90 bends a
resistance per unit length of tube?
..

http://www.copperinfo.co.uk/plumbing...ng-systems.pdf

On Sun, 29 Jan 2012 16:25:29 -0800 (PST), Onetap wrote:

Is there a nice handy look up table for 28mm copper 45 and 90
bends a
resistance per unit length of tube?

http://www.copperinfo.co.uk/plumbing...ers/downloads/
pub-150-copper-tubes-in-domestic-heating-systems.pdf

Thanks for that will have to inwardly digest the do a bit of number
crunching.

--
Cheers
Dave.

On Mon, 30 Jan 2012 23:47:36 +0000 (GMT), "Dave Liquorice"
wrote:

On Sun, 29 Jan 2012 16:25:29 -0800 (PST), Onetap wrote:

Is there a nice handy look up table for 28mm copper 45 and 90
bends a
resistance per unit length of tube?

http://www.copperinfo.co.uk/plumbing...ers/downloads/
pub-150-copper-tubes-in-domestic-heating-systems.pdf

Thanks for that will have to inwardly digest the do a bit of number
crunching.

I once fitted a formula to similar tables (Wednesbury Tube data - it was
a long time ago, hence the imperial units) to relate flow velocity, pipe
resistance and bore as follows:

R = y * (V ^ x)

where R = Resistance in inches of water per 100 foot pipe run
V = Flow rate in pounds per hour
x and y vary for different pipe sizes

Size(mm) x y
8 1.7650 1.225 *10^-2
10 1.7430 4.150 *10^-3
15 1.7180 5.836 *10^-4
22 1.7495 7.070 *10^-5
28 1.8913 6.648 *10^-6

For 8mm tube this is assumes 0.6mm wall thickness, for 10mm a 0.7mm
wall.

These are empirical formula that I derived from tables. If anyone has an
analytic version or a single formula that takes bore into account I
would like to have it.

From this a 22mm pipe has about 1/7th the resistance of a 15mm pipe of
the same length and flow rate. A 28mm pipe has about 1/30th the
resistance of 15mm.

I've got an excel sheet that plots these on a chart if anyone wants it.

--
Phil