The plumber's left for now

He had no trouble whatsoever filling up all the pipes by simply installing a small pump next to the boiler. The pump will have to stay there. He said if I plan to move water through all the radiators by sole means of gravity, I'll generate huge heating bills, because the water is obviously having problems flowing through the system all by itself. So I decided to buy that pump from him on the spot. It is second hand but practically new, and half price of a new one - not a bad deal. He's not finished yet, still has to change release valves on some radiators, but will only be able to show up again in about ten days. However, I can already heat the house if I want to, everything works, let's say, 90% perfectly.

I estimate the cost of installing the boiler and starting the whole system again will exceed 50% of the cost of the boiler. Which was not cheap to begin with - although a simple model and therefore one of the cheapest boilers available on the market. I could have paid at least twice as much for one.. so actually I'm saving. Still, it's a major expense.