Open vented system - air

[dormermike]

Hi

My old open vented y plan system sucks a lot of air when the heating is on but never when just the DHW like in summer. The F&E tank is on the first floor as I'm in a bungalow.

I can feel the air coming in and out of the f&e pipe when the pump kicks in and when it stops.

My plumber suggested lowering the f&e pipe outlet so that it sits in the water.

I am sure I read somewhere that it's not a good idea but I'm not sure why.. it would seem like it would solve the problem. .? or would it cause other issues..

Thanks
Mike

 

[Madrab]

You need to get to the bottom of why it's drawing in air. Pump positioning, speed, pipe blockages etc. Get your plumber to sort the problem out, not create more or mask existing. The expansion should be a min height above the F&E water height, this is primarily to avoid surge and certainly not in the water. A normal rule of thumb is 450mm above, this is basic level 2 stuff that your plumber should be well versed in if he's experienced.

 

[dormermike]

There is not enough room for 450mm so that would seem to be the problem. Am in a bungalow so don't have any space to go higher.

Why is dropping the pipe to below water level a bad idea?

Tbh I've lived with bleeding the boiler circuit 3 times a week for the past few years so can probably live with it until I can find a heating engineer who has more than "install a combi mate" in his vocab.

Just thought there might be a quick win by dropping the pipe with some push fit.

 

[Steelmasons]

Tbh I've lived with bleeding the boiler circuit 3 times a week for the past few years
.

System water would be orange in colour if that were the case...
Connect the cold feed into the open safety vent within loft space or airing cupboard.

 

[dormermike]

System water would be orange in colour if that were the case...
Connect the cold feed into the open safety vent within loft space or airing cupboard.

If what was the case? you think I'm telling porrkies about bleeding the rad ? lol

Connect cold feed to vent. OK. permenantly or temporary ? what is the purpose of what you are suggesting ?

 

[AGAS]

If what was the case? you think I'm telling porrkies about bleeding the rad ? lol

System water would be orange in colour if that were the case...
Connect the cold feed into the open safety vent within loft space or airing cupboard.

dormer mike you've been given a solution and your getting arssy

 

[dormermike]

dormer mike you've been given a solution and your getting arssy

Sorry. really don't mean to sound arsy. I am just not sure I understand what is being suggested...!

Apologies if I came across as a nobber

 

[Madrab]

When you do a combined feed and vent it all but removes the chance of air being drawn down the vent. How old is your system?

 

[dormermike]

Ahhhhhhhhhhh

Right OK. I already have a combined feed and vent. 15mm feed joins into 22mm vent approx 10" below tank. Vent pipe comes off feed behind pump.

Is that what steelmasons meant by "
Connect the cold feed into the open safety vent"

 

[dormermike]

System water would be orange in colour if that were the case...
Connect the cold feed into the open safety vent within loft space or airing cupboard.

So what does the comment about the orange water mean?

 

[Madrab]

If the system is constantly drawing in air then it promotes corrosion, therefore the water would usually turn rust coloured (orange).

 

[dormermike]

Ah OK. Took out a downstairs rad and the water was clear but there was a lot of black sludge.

 

[Hugh Jaleak]

Black sludge is the inside of your system, slowly dissolving. Really need at the very least to try and clean it out, sort the problem of air being sucked in and add some inhibitor

 

[Nige F]

There is not enough room for 450mm so that would seem to be the problem. Am in a bungalow so don't have any space to go higher.

.

Is there not a roof void

 

[dormermike]

The f&E is as high as it can go. There is no roof void.

So back to the original question if the pipe is sucking air in, would dropping that pipe below the water level work ?