Pressure and flow rate in CH pipes

Is there a simple (or instrumental/complex method if no simple way) of measuring:

- the pressure produced by a CH pump

Yes. You need the differential pressure though. One pressure alone is useless. Pressure gauges on the suction and delivery are used. With small/domestic pumps the differential pressure produced is small & the dubious accuracy of cheap gauges make this unreliable. You'd really want an electronic differential pressure meter which is connected to test-points (Binder or Test-Loc) in the pipes. The test points should be in a straight bit of pipe nlt 5D from any fittings. Drowned mercury manometers were used for this, until quite recently when mercury became very non-PC. The DP meters can be hired. Commissioning sets/meters are more intricate versions of the DP meter; not for the beginner.

- the flow rate in the pipes?

Yes. Usually you need a flow measuring device in the pipework. These are orifice meters. You measure the differential pressure, i.e., upstream & downstream of an orifice fitted into the pipe. The DP gives you the flow rate from a chart. Crane & Hattersley used to be the big UK makers. The DP is measured as above through Binder test points on the valves.

If you haven't got orifice meters, then you can get ultrasonic flow meters which are strapped to the pipe. These also can be hired. I don't recall the tecnical details of how they work, summat to do with Doppler effects. They do work.

UFH manifolds often have a mechanical flow meter.

- the hydraulic resistance of the whole or part of the system

Yes. Binder test points as for the pump DP measurements, but one on the flow, one on the return of the relevant zone.

If this is a flow/pump problem, you can estimate the system hydraulic resistance, e.g. from CIBSE guides. It's quite complex, but fairly easy when you've done if a few (hundred) times. You can also employ specialist commissioning contractors/technicians who will measure and balance commercial system flow rates, for a fee.

PS The pump curves would also give you the flow rate generated at a given DP. This assumes that the pump is working properly, which may not be a valid assumption.