Duetto water pump issue

Although I had my Duetto for three months now, I only managed to make the water system work now. I bought a new Shureflo 20 PSI pump, and although I knew that the pump should be activated by the switches in the taps (provided the 12V and the main pump switch are both on), the guy who installed it, told me that it works as soon as it detects low pressure, i.e. when you open a tap.
I have cold water in the sink and shower (by the way, the shower taps don't seem to have switches, as I can't hear them clicking when I turn them on), but the hot water taps don't work.
On the front page of the user manual sent to me by a very kind member of this forum, it was written by hand that you should run the pump for 5 minutes after filling the tank, with all taps off, until all system is full (including the boiler). I am afraid to do it though, since it's not the original pump. I'm worried not to damage it.
Any advice would be appreciated.
Thanks,
Laurentiu

The original Shurflo Trail King based system would have been entirely pressure-sensing. The system needs no tap switches anywhere - when a tap is opened the pressure drops, and the pump starts running. It's not unusual to find taps (especially retrofitted ones) with switches installed, but in a system like that they are just left unconnected.

When you've filled the fresh water tank, you need to run the pump (with one or all taps open) for a significant amount of time to fill the hot water tank and purge air out of the system. This will not harm a Trail King or similar pump.

Thanks a lot for your prompt reply. It was encouraging and I've been using the cold water taps for a couple of days now, but they're still "coughing", which means there is still air in the system. I ran the pump with just one hot water tap open for quite a while (probably 10 min) but there was no signs of water coming through, so I was worried to leave the pump on for longer.
Sorry for being such a novice, and thanks a lot, once again, for your valuable help. I can't wait to reach the stage when i'll be able to help other people, but if things continue to go wrong, I'll get some knowledge soon

If the boiler drain is closed, no water will be draining from under the van when you run the pump. If you see water under the van, look for the dump tap with a yellow lever. This will be close to the boiler on the inlet pipe and the yellow lever should be horizontal on either side of the valve.
Provided the above valve is closed, open a hot tap and let it run until spluttering stops.  This will happen when the boiler is full.  It has a 10 litre capacity.  It could take more than 10 minutes.  It will not harm the Shurflo.
Keith

I've found an image of the valve Keith mentioned, which may help you identify it.