How to Adjust the Flow Rate of a 24V Water Pump

use PWM and not variable voltage.

It depends on the design of the pump.If field connections are available separately from the armature, then field weakening is an option.The weaker the field, the faster the motor(but lower torque).

If armature and field are not readily separable, then variable supply voltage control is an option.Minimum voltage will depend on load.

A control valve from output side back to input side of pump,or back to reservoir, is another option.

Is pump impeller type, or Positive Displacement type?Piston,Wobble,Turbine?Lots of unknowns about your pump.

Why do you need to control the pump?Why not just let it run full flow for the entire curing period, unless there is a danger of freezing from ambient temperature?

You say you are hoping the added ice will keep up with demand, so that tells me you have not done a proper analysis of the problem to determine how much cooling will be required,size or spacing of cooling coils required,etc.

If this is just ad-hoc engineering, just take your best guess and go with it.

If you cannot find the time to do it right the first time, where will you find the time to do it over?(And probably at your own expense?)

My advice? Hire an engineer to help you with this problem.

I hope it works out for you.

Footnote to my previous reply:

I realize"large" is a relative term,depending on the experience level of the user.

I hope these structures will not be used in a circumstance where life or limb may be endangered if they collapse.

If so, your liability,both civil and criminal, is unlimited.Are your finances up for this possibility?

You mention using a 24 volt pump for safety reasons? That is the least of your worries.

I hope you are not building a dam.

To exclude myself from any future litigation, my only advice regarding this whole project is: GET AN ENGINEER AND DO IT RIGHT.

What is the power of your D.C motor that you will use ?

Simple.

Just turn the pump off when the temperature has reached the desired value and turn it back on when it is warming up. There should be enough thermal mass in the concrete to make these on/off cycles long enough to avoid damaging the motor / pump.

Most basic temperature controllers will have an on/off mode with hysteresis to activate your motor starter.

Agreed GA, and if your worried about melting your ice to keep up with the flow. Run a line from the pump outlet to the ice storage area and spray water over your ice blocks that should melt them just fine, but what happens to the ice when the pump is turned off? Will it all freeze giving you no water at all?

This ice flow water cooling engineering design reminds me of the time I had to go home and make a wooden wheel out of 1" ply wood since my spare was bad to get me the last half mile home. I was 16 and it worked but it was all just a guess.........