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Posted by Solar Flare on November 6, 2005, 4:22 am
 
Has anybody found a pumnp with more regulated flow?

We need one that can do a 30' head or more but never exceeds 2-3 gpm without
head. Maybe this isn't possible with these wimpy pumps and methods.

Possibly a multi speed pump. I know Grundfos has one but it is iron and I want
non-rusting.

Thanx Nick



Posted by Robert Scott on November 6, 2005, 12:36 pm
 
On Sat, 5 Nov 2005 23:22:42 -0500, "Solar  Flare"


Just about any pump can be turned into a variable speed pump with the
proper electronics.  If the flow can be measured, then it can be used
to close the loop.  Is there a market for such a controller?  That
would be something my company could develop if the need is there.
What is the advantage of limiting the flow in no-head situations?


-Robert Scott
 Ypsilanti, Michigan

Posted by nicksanspam on November 6, 2005, 1:01 pm
 

Lower power consumption. Perhaps you can also develop a smart whole
house fan controller and differential humidistat.

Nick


Posted by Solar Flare on November 6, 2005, 2:39 pm
 Yeah, lower power consumption and no returning cold water

I doubt synchronous motors can be speed varied with electronics. I know it can
be done but the motor will burn out after some time.



Posted by Christian Kaiser on November 6, 2005, 5:43 pm
 Well I've got a Grundfos UPS 25-60 pump, and it can be varied in speed in a
wide range.

My control offers two possibilities: wave packet system and phase angle.
Both work, though the wave packet system is loud (resonances throughout the
piping system).

WAVEP Wave packets - only for circulating pumps with standard motor
dimensions.

Here, individual half cycles are bled in to the pump motor. The pump runs on

pulses and only produces a smooth flow of the heat transfer medium when the

rotors moment of inertia has been overcome.

Benefit: Great dynamics of 1:10, well suited for usual commercial pumps

without internal electronics and a motor length of around 8 cm.

Drawback: Linearity depends on the pressure loss; there is some noise, not

suitable for pumps with evidently deviating motor diameters and / or length

from 8 cm.



PHASE Phase angle - for pumps and ventilation motors. The pump is switched
to the

grid within each half cycle at a certain point (phase).

Benefit: Suitable for almost all motor types

Drawback: Low dynamics of 1:3 for pumps. The device has to have a filter

upstream to fulfil the CE standards for interference suppression



Christian



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