Circulation pump capacity and overflow valve

Currently, I am planning to remove the overcurrent valve from my heat pump with underfloor heating, but now an acquaintance who is a heating engineer has unsettled me and said that this is nonsense and I should leave the [ÜSV] as well as the [ERR] in.

The following applies to the system:

Max. nominal volume flow heat pump:
at 5K = 540 l/h

Underfloor heating hydraulics calculated at ~ 850 l/h with a pressure loss of 100 mbar

max. [ÜSV] response pressure ~ 300 mbar

Lowest delivery head of the heating pump 400 mbar at ~ 1000 l/h; only from about 1000 l/h does the delivery head drop, e.g., down to 380 mbar.

If I open all heating circuits fully without throttling anything, I manage max. 700 liters in the heating circuit. If I then go and at least throttle some short heating circuits, the pump always hovers around 610 l/h.

Therefore, I believe that the minimum delivery pressure of the UWP is already so high that despite the pressure loss in the heating circuit, the overcurrent valve always opens, and I therefore never achieve the maximum possible volume flow in the heating circuit or heating circuit manifold.

Pump pushes up to just under 1000 l/h:

400 mbar minus 100 mbar for the worst heating circuit leaves 300 mbar up to 1000 l/h; but the [ÜSV] already opens at 300 mbar.

Regarding the theory, the acquaintance said that this is nonsense and unnecessary to remove the [ÜSV] because my system is already running optimally, and that I would now try to turn the smallest adjustment screws only to optimize the system to death?

Am I now on the wrong track or is there a spark of truth in my thoughts? Or has my acquaintance rightly unsettled me? Otherwise, I wanted to deactivate the [ÜSV] between the years.

Usually, you can adjust the ÜS. So also completely off. If the heat pump then gets enough flow during defrosting (minimum amount is in the manual), you can remove it. The prerequisite, of course, is that the ERR do not start locking off entire rooms, so remove those first. That always works.

ERR is out of order. I don’t think I can completely close the ÜSV, I believe it always opens as soon as the max. pressure of 300 mbar is exceeded.

It is a Watts ÜSV 16L

what exactly is the question?

I find it astonishing that anyone still wants to install a [ÜSV] today.

A pressure-difference-controlled electronically regulated [UWP] performs this function by itself.
And if too many radiators are turned off, the [UWP] simply reduces its output by itself.
Nowadays it doesn't cost more than €200 (Wilo or Danfoss).

Or what is it actually about?

The delivery head has no influence here. The pump is only supposed to circulate, not generate any delivery head.

It's about the pump not circulating enough. (House is still warm) Approximately 850 l/h was calculated to flow through if hydraulically balanced, but a maximum of 700 l/h unbalanced flows through.

Therefore, I thought the much-criticized ÜSV is to blame? Unless the calculation is incorrect.

Oh, I thought you were afraid that too much flow would bypass the HK through the ÜSV. The ÜSV cannot be to blame for too low total flow, that's what it's there for.

There are also ÜSVs that can only be set to a max response pressure. Unfortunately, I also have one like that.