Heating Help

high static pressure in a inclosed piping system

I know I know. Not a real exciting subject. When filling a glycol treated enclosed system. Is it any harder on the system pumps if the static ( no pump running) is at 20 psi vs. 80 psi. prior to system start up.
Wouldn't the system just be trying to create a delta P across the pump. I would not think static pressure high or low would make a difference. I do know that you need a minimum amount of static pressure.
I open to other theorys. Please weigh in.
Thanks.

So long as you are within manufacturers allowable pressures...

It doesn't matter. As you noted, in order for the pump to put out what it is rated for, you MUST provide the minimum net positive suction head (pressure, usually around 5 PSI).

Other than that, the pump really doesn't care what static pressure it is operating under, and will produce the same pressure differentials at 20 as it will at 80.

The only advantage of running a higher static fill pressure is that the larger bubbles get smaller (compression) and the boiling point of the fluid is higher.

ME

remember the exp tank

pre-charge needs to be adjusted to fill pressure. And expansion tank sizing with glycol, and elevated pressures needs to be adjusted.

Seems the glycol solar systems in Europe run much higher fill to supress boiling as ME mentioned. Which is why the solar pump stations you get from over there have 6 bar, about 87 psi, pressure relief valves installed.

pressure

You have supply and return lines, and static pressure in supply line cancels static pressure in the return line. all what counts is pressure losses when pumps is running, and they will be the same with 20 psi and 80 psi. Expansion tank must be pumped up. all pressure relieve valves must be checked for proper ratings and replaced if necessary.