Does the F + E tank vent pipe need to be above or in the water line?

[friendlyaviator]

There is a reason I ask, my water level is quite high and as such it's submerging the vent pipe. Is this ok? If not why not?

 

[albabe]

If the water levels high in the tank, it will take less time to fill to overflow level if there is a problem with the system and the expansion pipe should discharge expanded water into the tank. Even if the cold feed from the tank starts to replace the expanding water there can be sufficient time for an overflow. The cold feed is probably 15mm whereas the expansion should be 22mm minimum.
Should the overflow pipe, get blocked you could get a wet ceiling.
If the expansion pipe is submerged, there is a possibility that water could be sucked into the pipe, especially on pump start up. If this is a significant amount of water the ballvalve could start to replace it, this could increase the risk of overflow.

 

[friendlyaviator]

Thanks for the reply. I've also notived the highest bend in the vent pipe is only about 150mm above the water-line. My research shows this is supposed to be 450mm above the water-line.

I am in the process of modifying this vent pipe and in doing so I will ensure it does not dip into the water.

What will this insufficient height mean for my system?

 

[AlexGas]

Vent pipe shall terminate not less than twice the internal diameter of the ventpipe above the top of the float operated valve or top of the overflow pipe whichever is the higher.

 

[JJ The Plumber]

Take the open vent 18 inches above the tank if possible, this will also help if you have any issues with air.

JJ

 

[mountainman]

Vent pipe shall terminate not less than twice the internal diameter of the ventpipe above the top of the float operated valve or top of the overflow pipe whichever is the higher.

That's easy for you to say. 🙂

 

[ecowarm]

There is a reason I ask, my water level is quite high and as such it's submerging the vent pipe. Is this ok? If not why not?

Not good for the vent/ expansion pipe to be submerged, it will circulate hot water in the expansion cistern and cause problems with sludge in the system. Also investigate the reason for the high level in the cistern, ball valve passing or set to high? or it could be the coil in the hot water cylinder split.

 

[friendlyaviator]

To all the replies,

I have experienced air in the system since I went crazy on the radiators and cleaned them all with a hose.

Intermittently I got gurgling sounds through the pump, pipes and radiators. It was so intermittent it would sometimes run for hours with no gurgling then all of a sudden was terrible.

Anyway, I have raised the vent loop to over 450mm above the water level, the ball cock was set way too high too, so I bent that down a bit. (It wasn't letting by or a split coil as it filled with the most gentle push down on the ball)

I've literally just finished all the above so I can only monitor it over the next few days and see what happens.

I'll repost when it's been a few days.

Thanks again

 

[albabe]

You have introduced fresh water into the system, this will cause "air" to circulate in the system until you have bled it out. Make sure to stop the pump running when bleeding the radiators.
If the height to the top of the expansion pipe bend is too low it is very easy for the pump to push water over and into the tank if the expansion pipe is connected to the positive side of the system. Every time this happens, aerated water from the tank will replace the water which has been ejected.
This is more likley to happen on pump start up.