How to check F&E tank and vent are not blocked

[Mmcgar]

Hi all,

I have an indirect open vented system with standard boiler and hot water cylinder, I have 2 quick questions about how to check the system please I'd appreciate if anyone could give me a quick "how yo" for these checks.

How can I check the F&E tank is filling the system properly when required? I just want to make sure it is not blocked

Also I would like to check that the vent is not blocked, I understand this is highly important as the cylinder could pretty much explode if it cannot properly vent

Thanks I'm advance

 

[Newboy]

Drain a little water out of your system and the F&E cistern should refill - worth first checking that the cistern isn't full of muck and dirt that may be drawn into the feed.

It would be unusual for the cylinder vent to be blocked - are you mixing up the HW cylinder vent with the heating loop vent?

 

[dilalio]

Why are you asking this?
What problems are you having and what are the symptoms?

 

[dilalio]

It is quite common, on an old system, for the close-coupled 'H' section, formed by the feed and vent pipe to the f&e tank, just before the pump, (see @newboy's image above) to become blocked.

 

[HERTS P&D]

You can check the above with a strong magnet.

Andy

 

[DaveHerns]

Why does this happen? Why does the crud in the system rise to the top of the system instead of sinking to the bottom as I assume it's heavier than water?

 

[amstel]

Drain a little water out of your system and the F&E cistern should refill - worth first checking that the cistern isn't full of muck and dirt that may be drawn into the feed.

It would be unusual for the cylinder vent to be blocked - are you mixing up the HW cylinder vent with the heating loop vent?

Hello, just out of interest, why is the cold feed just after the vent inverted ?, mine is same, cheers.

 

[Mmcgar]

Hi thanks for the reply.

I'm just looking at different things to try and troubleshoot some issues.

Back story is I had some work done a on a couple of radiators about a month or so ago which involved draining the system down. Since then iv had some issues, mainly these are having to bleed the system a lot (sometimes 2-3 times per week) due to noise. Also generally the noise coming from the system (mainly the cylinder I think) is noticeably louder, particularly when the room stat reaches temperature, closes the zone valve and the pump goes into an 8 minute overrun where it circulates through the cylinder (no stat) and the bypass.

My thinking is, having to bleed the system a lot would indicate a leek however the water in the F&E tank looks old /stale, which in itself is concerning as the system was only recently drained. So is it possible there is not enough water in the system which is why air has space to get in? 1 thing to note is that the lever on the F&E tank seemed to be set low, the level of water was only half way covering the pipe if that makes sense. I have no adjusted this.

So basically that's my issues, as I said I'm just trying to do a bit of trouble shooting to see what's causing the issues. I'm obviously having difficulty getting people available to come out this time of year which is why I'm trying to do it myself

Hope that makes sense, cheers

 

[Roger928]

Hello, just out of interest, why is the cold feed just after the vent inverted ?,

It helps prevent heat rising up the cold feed and heating the f&e cistern.

 

[Newboy]

indicate a leek

If you've got a leek in the system you need a greengrocer!

This is a leak

mainly these are having to bleed the system a lot (sometimes 2-3 times per week)

If you're bleeding that often then either:

1) You have a significant leak
2) There is a massive amount of corrosion in your system
3) You're not actually bleeding the system
4) Air is being drawn into the system

1 thing to note is that the lever on the F&E tank seemed to be set low, the level of water was only half way covering the pipe

Which pipe is only half covered? - the feed pipe (low down on the side of the F&E cistern)?

 

[Mmcgar]

It was the feed pipe, the ball valve lever had been bent down so it was only filling to a point half way up the pipe.

When I'm bleeding the system I am getting a couple of seconds worth of air coming out before the water, this usually happens at the cylinder bleed point (highest point of system) it sometimes happens at a certain bedroom aswell

I'm terms of air getting drawn into system, I suspected this may be the case there is a noise from the pump, it sounds to me like there is air in it (I am completely uneducated I'm this type of thing tho so I could be talking nonsense)

 

[Newboy]

The water level in the F&E cistern is too low - usually about 4" - 6" and covering the feed pipe. Water needs to be clean and debris free.

System needs to be off (at last the pump shouldn't be running) before bleeding - bleed at rads, pump and (hopefully) vent on highest pipework near to cylinder.

It's possible that your feed pipe is blocked or restricted although this should have been evident when the work was done a few months ago.

Hopefully the system was dosed with corrosion inhibitor when it was refilled.

 

[Mmcgar]

Hi, thanks for the reply. Yeah iv been waiting until pump has stopped /system is off before bleeding.

The guys that done the work said they put inhibitor in.......

So I suppose I should open the drain outside the house and watch to see if the water level drops In the F&E tank? Generally speaking how much water has to be drained out before the F&E tank will start refilling? Also, is there normally any valves /idolaters on the outgoing feed pipe?

Finally would it do any harm to add more inhibitor myself or can you have top high a concentration?

Thanks again

 

[Roger928]

Also, is there normally any valves /idolaters on the outgoing feed pipe?

Should be no valves fitted to a feed pipe.
Though I was at one a while back fitting a radiator and the guy said he could not get the air out of the upstairs rads and they heated about half way up. Been that way for several years he said.
Turned out someone had fitted an isolator on the feed pipe and someone had turned it off.
When I returned to him a week later to fit a new shower he told me the radiator I had fitted wasn't working anymore.
Someone had turned it off.
And he blamed me.

 

[AGAS]

1 thing to note is that the lever on the F&E tank seemed to be set low, the level of water was only half way covering the pipe if that makes sense. I have no adjusted this.

, the ball valve lever had been bent down so it was only filling to a point half way up the pipe.

bend the ball valve arm back up and let the system fill back up and vent .