Filling via the open vent

I had the problem of no hot water but green light on and red LED light flashing normally, but feeder tank was empty. Filled feeder tank but still no hot water. I noticed in another thread that someone suggested filling via the open vent - which i did and i now have hot water. Thank you for that

But i have two questions:

1) How do i know how far/long to keep on pouring water in the open vent?

2) I am guessing that the fact i needed to fill via the open vent suggests that the feeder tank is not somehow blocked from doing its normal operation and therefore i need to top up via the open vent from here on in?

andrewn

You could try putting some sludge remove down the cold feed

I agree with Mike, try using some sludge remover which helps in most cases.