Spluttering tap

[Smcart5]

I have a tap at my parents house and occasionally when turned on it stops working, splutters and chucks out some air, then starts trickling water out slowly and build until its flowing properly again

Somehow air is getting into it and i can't figure out where, i am only college educated and have no practice working live, but i still feel ashamed i have no idea what the cause is

The system is indirect and its worked fine up to now, the only thing i could think of was air being sucked in through the open vent pipe, but not sure how that can happen as everything seems to be setup correctly.

Edit, its the hot water tap.

 

[Winston]

Fit a automatic air valve on the hot feed near the boiler, I presume its the hot!

 

[Bernie2]

Could you explain a bit more about what you mean by indirect please?

Also which and where is the tap that has the problem?

The vent from the top of the cylinder to over the main cistern is usually the domestic hot water vent.

To avoid one pipe circulation the vent should run level from the top of the cylinder for about 450mm before it splits at the tee for the dhw and vent.

Another problem can be an under sized cylinder cold feed, which can't cope with the amount of water drawn off and so when somebody draws hot water it pulls air down the vent.

Sometimes if the supply is too small, you can get away with taking the hot pipe into the top of the cylinder instead of the combined vent and hot water.

Sometimes cleaning the storage cistern helps and making sure the cylinder cold feed is not blocked and that it has full bore stop valves on.

Sometime the bottom of the cylinder can be full of sludge or lime scale can be virtually anywhere on the hot side.

If these ideas are no good come back on, we'll try something else!

Good fortune!

 

[Smcart5]

Thanks for the replies, i'll have another look at the system tomorrow and go over both post suggestions.
If i can't figure out the cause of the air getting in i'll try putting an auto air vent on the hot water draw off if there isn't one there already.