Bubbling in F & E tank????

[Ljbaughn]

There is a loud bang coming from the attic when the heating is turned on. It does not make a noise every time it is turned on. Perhaps once a week or so. It did it again yesterday, so this time I went up in the loft. It’s definitely the heating overflow tank but I don’t think it’s the valve. By the time I got the ladder it has virtually stopped, but when I looked in the tank air was bubbling up (quite violently) from the bottom of the tank. Turning the heating off makes it stop. When it does do it, it seems like a lot of air. Seems like more than could be in the system ? This morning the heating came on OK, with no noise, but the last radiator in the system (top floor shower room) had a loads of air in it.

Couple of things to note.
I don’t get any noise from the radiators just the loft tank.
It been over a week between occurrences even though the heating has been on every day.
My heating system is pumped (not gravity fed) due to the way the replacement boiler was connected up (before I bought the house).

Please help!

 

[lame plumber]

for one reason or another your getting air iinto your sstem and its not vent through the vent pipe over the cwsc but via the exp pipe into the cwsc, so you may well have a blockage in your pipework. best to get a heating engineer in who understands older layouts to check it out for you.

 

[Ljbaughn]

You mentioned there the cwsc. I'm referring to the f and e tank. Also you say exp pipe but isn't that the same as the vent pipe? I would have thought air was coming up through cold feed pipe to the boiler....

 

[lame plumber]

sxorry meant f&e tank, being dozy feed and expn pipe is not the same as the vent pipe as one is a vent and the other the feed pipe and allows for water expansion. some do combine the two whch then leads to blockages over time at the junction of the 2.

 

[Ljbaughn]

How is air getting into the system in the first place? It's an open vented system. What's causing the air the be forced up that pipe? Also why does turning the heating system on cause this to occur?

 

[lame plumber]

water and air expand when heated, one reason you see it coming up feed/expn pipe, problems with neutral point and pump position another, really need to get someone to look at it