CampinGazz wrote:
I'm about to order my radiators for the van, (Ultraheat do down to 200mm
wide rads, just waiting for a price) still waiting for the boiler
(eberspacher diesel fueled hot water furnace) to arrive, so whilst i'm
waiting i'm going to run the pipes for the radiators.
snip
problem i see is, how on earth do i stop the first radiator with a full open
flow valve allowing all the hot water to go through the rad and into the
return line, thus avoiding the water going round the rest of the pipework?

Balancing.
The other valve is turned down so that with all TRVs open, there is a
proportional flow to them all.

You can have a bypass valve, which operates when the pressure rises
above a threshold, and allows water flow through a loop round the pump.