On 27/12/2016 18:02, GB wrote:
On 27/12/2016 15:59, Phil L wrote:

There will be a filling loop under the boiler allowing re-pressurisation,
and a gauge showing system pressure. It will currently be on zero and it
needs to be over 1 bar after all the rads have been bled.

I am surprised that the boiler lights at all if the pressure is that low
that there's nothing in the upstairs system at all.

Hmm. I know a Vaillant that will light up, once to the detriment of the
heat exchanger.