Air coming out of hot tap

[Genesis2k]

Hello all

i've got a friend that has been complaining that when he runs his hot tap either down stairs or up in his bathroom that it was running and cutting in with air.
when i went to look at his system i found that the vent pipe on his F + E tank was sucking in air.. when i placed my hand over the vent pipe it started to run fine.. obviously blocking the release vent is not an option so does anybody have some ideas on how i can sort it out for him??


cheers

 

[Softus]

Remove the blockage - it will be in either the cold feed to the cylinder or the hot outlet at the top.

 

[JohnD]

"the vent pipe on his F + E tank "

Do you mean the small tank? 18" x 12" x 12" or so?

This should have no relevance to tap water.

If you mean the big cold water tank, then yes, could be blocked. e.g. with a drowned mouse or pigeon, or loft insulation fallen in. I would have thought the supply pipe rather than the outlet, but Softus is one of the plumbing princes, even though he is just a lad.

 

[Softus]

Oh jeepers JohnD, that's going to bring some pretty meaty wrath from my elders and betters on the forum.

 

[JohnD]

better?

 

[Softus]

Perfect. I'm much more comfortable when being demeaned.

 

[Slugbabydotcom]

The first time I came across this was in 1982 as an apprentice. I can still remember the house!
The culprit was a malleable iron elbow that was fitted on the feed pipe to the cylinder. It had rusted inside and created the blockage.
A restriction here causes air to be sucked in at the vent. I sussed out that if I put a temporary stop end on the vent that the problem would stop.

 

[Softus]

...It had rusted inside and created the blockage.
A restriction here causes air to be sucked in at the vent.

I concur.

And the same effect can be had by chipping off bits of foam lagging and dropping them into the cylinder - they bob-up and block the outlet. This is quite hard to do of course, but I guess there are people out there who practise until they've got it right.

 

[Slugbabydotcom]

Forgot to mention that a gate valve in this pipe that isn't opened fully can have the same effect

 

[Nige F]

The first time I came across this was in 1982 as an apprentice. I can still remember the house!
The culprit was a malleable iron elbow that was fitted on the feed pipe to the cylinder. It had rusted inside and created the blockage.
.

...beat that by 8 years and the other apprentice was left like the Dutch boy and the dyke...for an hour till we got back ...yep it broke off in his hand