Thanks for the reply, but it does not loose any oil, think it is going back past the NRV over a period of over 4hrs. Have located a seperate NRV on the internet when it come will dismantle the old one and examin and hopefully repair, if not will fit the replaecment
joander
wallstar oil boiler
Works perfectly ok through the day, but if left off overnight goes out on timer lockout on first start up. Reset and bleed the oil supply everything ok till next time it goes off overnight.
When boiler first installed the fire valve was seperate to the check valve, HRM...