might just be metal expanding on first heat up
might just be metal expanding on first heat up
Oil fired boilers in general do not need ABVs as the Hx holds 20/25 litres of water which acts as a buffer so when the boiler+ pump cuts out, the water temperature (from a target temp of say 70C) will not rise > 90C/95C, a long way from the hi limit lockout of 113C. Gas boilers have a Hx content of only a few litres and this is why they have a timed pump overrun after all zone valves shut, the water then has no where to go so need a ABV.
Reply to the thread, titled "Inadequate Circulator Pump?" which is posted in Central Heating Forum on Electricians Forums.