Alde 3020HE advice please

We have a 2020 Adria van with Alde 3020HE wet heating. Our previous couple of vans also had Alde so we’re not new to it.

The current van/system just doesn’t seem to be as good at warming up the van (no problem with hot water). We have never run it on gas, only mains as we use EHU, tending to simply switch on/off using the thermostat to control it. The pipes running from the bottom end of the boiler are (very) hot, and there is some warmth detectable emanating from odd spots around the van, but not consistently so. On consulting the instructions, these symptoms read as though there could be air in the system. So the obvious thing is to bleed the system. But where are the bleed valves? I can see one at the end of the low level ‘radiator’ in the bedroom, but the instructions are not specific in terms of where or how many.

I’m sure that the system must be pretty much the same across all brands of van, so......

1. does anyone agree or disagree with my guess it’s air related? If not what else?

2. where are bleed valves?

the van goes in for its first service in about a month, so I can get it checked then, but as we are away at present in the unseasonably cool May, I’d like to sort if possible.

thanks

Ian