Im wanting to install this Pump for my open type solar hot water
heater (Florida) :
I want to be able to adjust the water flow rate thru the solar
collector when im setting up the system, and need to know how far I
can throttle down the water flow discharge without adversely affecting
the Pump/Motor ? The Pump Specs maxes the head out at 9 ' but my
system will only have 4' total , so I want to put in an adjustable
flow control valve right after the pump. Thanks for helping.
Watch your current draw... not a real good idea to excede that unless you
want to burn up the pump motor..... also be carefull you don't cause the
pump to cavitate.... thats not a good thing either.
So then, are you saying that I can throttle down the flow so long as i
dont exceed the amp draw of the pumps motor ? Thanks.
Or cause the pump to cavitate.... cavitation will cause the pump to eat
itself from the inside out, an you won't even know about the damage until
its too late.
Here is what the Rep. at Taco Pump just said : ' Any of our circs can
operate when throttled right back. All of the 00 circs are impedance
protected so will protect the motor even in a locked rotor
situation.' So, it seems they can be throttled back pretty far
without harm to the pump/motor.
The spec sheet on this pump shows the cartridge impeller, and it looks like
a simple centrifugal pump. These pumps typically draw the most current when
they are moving the maximum volume of water they are designed to pump per
minute. Restricting the discharge at the **outlet** on these pumps causes
the motor to actually have less of a load on them than when pumping the full
flow. Cavitation will result only when the suction intake of the pump is
Grumpy's (Tony) suggestion of a bypass around the collector sounds good too,
but will not reduce the amperage the motor draws in bypass mode.
The answer to your question is that you can throttle it down a lot without
harming the pump. It needs just enough flow to lubricate and cool the
impellor and bearings. It depends on how long you will run it throttled
which isn't clear from your post. If the time is short then you could stop
the flow entirely for, say 3 to 5 minutes. If the setup is permanent then
you could throttle it to 1/4 or 1/3 of the peak flow with no problems. Some
pumps could be throttled to 10% of their peak flows.
Your post raises some questions beyond what you asked such as;
- a system with only 4' of head seems very low to allow for vertical lift
plus system head losses.
- a pump that makes only 9' of head is very low.
- throttling makes noise
- throttling releases air from the water which increases bubble problems.
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