True variable speed pump

MarylandJoe

Does anyone know of a true variable speed pump. One that can drop down to 1 or 2 GPM?
I have an HEC-2 and it doesn't slow down that much. The basic application is hot water baseboard circulator configuration, but not exactly.
thank you

Dave H_2

Joe,
The HEC-2 does have a minimum speed (see here http://www.taco-hvac.com/uploads/FileLibrary/100-101.pdf) for the performance curve. You can get to the low speed and achieve that 1-2 gpm you are looking for. 1 to 2 gallons or minute is 20,0000 BTU's on a design day. If your system is about that size, you are right, it will be hard to vary below that speed.

How much baseboard is connected to your system?
Also, are you looking for a variable speed circulator or a high efficient ECM circulator?

Dave H

t4chi

https://forum.heatinghelp.com/discussion/comment/1376564#Comment_1376564

Why not both?

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1813206#Comment_1813206

Can you provide the total feet of element in your baseboard system. That is the part of your radiators with the aluminum fins. and how many fins per inch?

And I believe @Dave H_2 may have a typo. The rule of thumb for 2 GPM is 20,000 BTU. (that is based on a 20° temperature drop between the supply temperature and the return temperature.)

And you can get a Pump with temperature probe to be placed on the supply and return pipes and set the ∆T in order to get that 20° difference, or you can get a generic ECM that will just find a nice pressure differential without using the sensors.

And Yes, you will get lower operating cost either way. So the question is do you only need lower cost operation, or do you want something else also?

Dave H_2

@t4chi

When this post was written in 2015, Taco had the option of AC variable speed circs and we also had a Delta T ecm at the time.

These circs have a minimum speed and I was curious what we were connecting it to

DCContrarian

Grundfos UPMXL:

hot_rod

When you say "true variable speed" something needs to tell the circ what speed to run. Either sensors or the delta P operation, controlled by the algorithms in the software.

If you want a manually adjustable ECM variable speed, the B&G Vario has a dial to dial in required speeds.

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jumper

Varying the speed of any dynamic machine like a centrifugal pump cannot produce every flow one may want. You'd think that a positive displacement pump can……