A heating pump, is actually a circulator, they work by displacing water in the circuit, however, there has to be a build up of pressure to move water from A to B.

There are several types of flushing kits, and you need to say what type you had, for example, as above a circulator displaces water, from A to B, but a flushing machine, takes water from C, pushes it down A and B goes back in the bucket, so it's not displacing water and a different kettle of fish.

A simple answer is yes there must be a build up of pressure, from the velocity.

Don't know if I can find a pic from years ago, but it shows a circulator with pressure gauges, and nearly 1bar differential between the inlet and outlet.

You can't have flow without pressure but that's all a red herring.

The proper proceedure for testing the unit is detailed in the manual....

http://www.kamco.co.uk/GuidanceNotes/PDF/FlowCheck.pdf

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I would expect a hire center to use the manufacturers recommended test proceedure especially as..

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No mention of testing connections by simply "pulling on them". Well ok it does say to check the connections as well but you know what I mean.

Thanks chaps.

How did the hose come off?  The hose threads onto the machine against a washer, so you'll get leakage from the connection, tighten up jobs a good un, or have they changed the way you connect the CF30 hoses, mine is about 4/5 years old now.