Gravity system - water from vent pipe into F&E tank!

[stowbiz]

Hi
Wonder if anyone could help?
I have a Baxi 38RS boiler with an open vented system. I had it powerflushed and a new pump installed about a year ago and all has been working fine.

Recently there has been water flowing from the vent pipe into the F&E tank. It is in a ground floor flat so the tank is at ceiling level on top of kitchen cupboards.

I tried turning down the boiler level, turning down the pump (to 1) and even bending the ball cock down in the F&E tank. All to no avail.

When I turned the water tank thermostat down (from 60 to 45) it stopped. However the hot water was then not hot enough! At that point (with tepid water in the tank) I turned the tank stat back to 55 and that called demand from the boiler which instantly started running water from the vent pipe again! Very odd!

I have also discovered that turning off a radiator in the hallway (from its valve) seems to resolve the problem.

Any thoughts would be most appreciated. I have a plumber friend (on the phone - lives in a different part of the country) who is stumped. I am going to get someone to look at the system, but like so many other posts, if you have some information beforehand it's often a big help!!
Thanks,
John.

 

[Nige F]

leave the hall rad turned off until all the snow is gone . then plumber`s rates ...and Agile`s -who is in London , will go back to normal

 

[stowbiz]

Sounds like a good plan!
But I wonder if anyone knows what the fault could be in the meantime?

 

[ManxPlumber]

Your stored hot water should not be stored at temperatures below 60°C (140°F) to avoid the risk of legionella!

 

[stowbiz]

Thanks!
I've since turned it back up to 60 for the water.

 

[wetshoes]

Where the cold feed from the f&e tamk joins the system (could be just before the pump and in 15mm pipe) can you get a small fridge magnet to stick anywhere ?

 

[Nige F]

Sounds like a good plan!
But I wonder if anyone knows what the fault could be in the meantime?

not without looking , with the low head from f+ e tank it could be incorrect piping or cold feed block.

 

[stowbiz]

Thanks wetshoes and nige f.

"with the low head from f+ e tank it could be incorrect piping"

I've lived with it for the past 4 years and it has been fine.

Will check out the cold feed with a magnet for the possibility of a block. Thanks for that.
What is the resolution to that prob? Would the powerflush I had, have affected the cold feed?
Thanks.

 

[wetshoes]

If a small magnet sticks just cut out pipework and re-do with new, not a big deal.

 

[Agile]

You dont say why you had it power flushed.

Usually thats because of sludge.

Equally usually, pumping over is caused by sludge.

Be aware that pumping over creates sludge in a VERY short time. Often one radiator more will block each day that a system pumps over.

Unless pumping over is discovered very quickly it becomes very costly to clean the system again.

Your feed pipe is not blocked otherwise when it pumps over the tank would fill up.

You have not been fiddling with pump speeds have you? Many otherwise OK systems will pump over if the pump is set to "3".

Tony

 

[wetshoes]

You say you're in a flat ? - does any pipework go under the floor ?
(perfect place for blockages sludge etc!)

 

[stowbiz]

Thanks Agile,
That's very useful!
I had it powerflushed as I know it's an ageing system and was a having a rad moved. So when draining and I had the flush done, then, inhibitor was put back in the system. I thought it would be more cost effective to run.

The pump was on 2 and it is now on 1 since this problem started.

Wetshoes:
Yes it's a ground floor flat. And yes pipework does indeed go under the floor!

Baffling!!

 

[wetshoes]

Agile - blocked cold feed & pumping over is common fault -so I disagree there !
But do agree with sludge /blockage in rest of system maybe being the fault
as it seems that pipework is creating "sumps" !

 

[nogoodatfaultfinding]

Agile is right

9 out of 10 times if its pumping over its due to the section between the cold and the vent.

Tis can be easily solved by the introduction of a part which name escapes me at the moment but i have fitted several of.

 

[wetshoes]

Piece of new pipe ?