Water discharging from the loft vent pipe as CH turns off?

[Markw996]

Hi,
I have just moved into my first home, a 2 bed semi-detatched and as the title says I have a very noisy central heating system.

As it comes on I get lots of bubbling / gurgling noises that last about 10 seconds and seem to originate from either the upstairs radiators or the airing cupboard.

Also as the central heating clicks off it sounds like someone emptying a bucket of water up in the loft right above my bedroom (very worrying the first time it happened!).
I traced the loft noise to the expansion tank in the loft where, as the heating clicks off, I am getting about half a litre of water discharging from the vent pipe back into the tank.

The system is open vented circa 1992 and I take the vent pipe to be the one that rises about a foot above the tank, then bends in a U shape back down into the tank.

I've had breif discussions with a plumber friend and he says it could be the boiler thermostat?!? but I suspect it is more likely to be air in the system somewhere (although I am certainly not clued up on central heating systems) as I did have to bleed a lot of air from by bathroom radiator when I first moved into the house due to it being very cold at the top.

Just to summarise:
I have 2 tanks in my loft and the problem is relating to the smaller tank which does the central heating.
My boiler is located in a downstairs cupboard.
My airing cupboard is upstairs and contains an immersion tank, pump, and a motorised valve of some sort.

I hope someone can help as the noises wake me up in the mornings and annoy the hell out of me in the evenings! 😱(

Many Thanks,
Mark.

 

[yorkieplumber]

Reg Man thinks you and i think same way, am suprised by the lack of knowledge on this plumbing forum, to be quite honest am shocked.

 

[yorkieplumber]

In the old days when i was a wee lad systems were mainly gravity primaries in 28mm, and pumped heating circuit, 28mm flow from boiler went to cylinder flow on coil then you put a tee in a number 26 and the 22mm end carried on as the vent over expansion tank, the cold feed was on the return side of the cylinder coil. I think this is the system you refering to jase158.

 

[marinegmillie]

F&e vent pipe needs to be 450mm above cisten then back down in to cisten. Could join feed and vent with air separator.

 

[yorkieplumber]

Agree with marinegmillie, aerjec (air separator)

 

[Markw996]

Markw966 if you dont know which the vent pipe is and boiler flow, you need to call a proffesional in because if you alter the pipework and block the vent/expansion you could have some serious issuses, without been on site it is sometimes difficult to give a diagnosses, the fitting of a aerjec made by myson (i think) is a simple job to fit, but you need to be reasonable compatent, hope this helps.

Hi, I appreciate your comments.

This is my first house and my first ever look at a central heating system. I am learning fast and have bought 2 books and a DVD so that I can educate myself as to how it all works. To put you in the picture, I am competant with soldering and replumbed my parents new kitchen with ease.

I'm sure I will work out the best way to fit an aerjec given time to read the books (very in-depth) but I was just asking how I determine which is the boiler flow, and which is the return? They are marked on the boiler of course, but they travel around the house a bit before reaching the airing cupboard (where the mass of pipework is still a little alien to me).

Thanks to all the usefull posts, I like to know how things work so I can keep on top of things before they go wrong i.e. I never would have let the expansion tank get so scaled up as the previous owner has, I'll be checking that every few months!

For now, am I getting warmer? 😕



Thanks,
Mark.

 

[marinegmillie]

Cold feed and vent go up a foot with ya arrows, spot on.

 

[jase158]

This is what everything is?
To everyone who say i am wronge, this is the way i got taught Last year.
So obviously you have all done it and maybe there are hundreds of them out there but that doesnt mean it is right?

 

[marinegmillie]

Spot on jase158!

 

[yorkieplumber]

Agree spot on!

 

[yorkieplumber]

but in a earlier post jase, you said it was wrong, am confused now.

 

[Reg Man]

Jase158, I take it that we can now disregard your post number 18, and we will go with your post number 22.

 

[marinegmillie]

I think what he ment is where the cold feed and vent is piped to pump, the cold feed is quite direct into pump, maybe pulling in some water hence venting back over to get rid, just a thought.

 

[jase158]

but in a earlier post jase, you said it was wrong, am confused now.

I was saying the arrowed pipe is wrong as it is pumping water through the return? the opposite way that you want it? I have never seen one of these installed like this?
And secondly I have never seen a fully pumped system this way? I have learnt something and it proves that college is absolutely useless, all my diagrams in my books show the vent and cold feed going into the boiler, but the pump should be after the vent and cold feed. Surely there must be another way as this looks to me like it will draw water from the F and E tank.

 

[jase158]

I think what he ment is where the cold feed and vent is piped to pump, the cold feed is quite direct into pump, maybe pulling in some water hence venting back over to get rid, just a thought.

finally somebody who understands, is there no other way that this can be piped up?
And for all those who say that this is ancient plumbing, my plumbing doesnt even have a pump. So pumped central heating only cant be that ancient.

 

[Reg Man]

Jase158, I thinking about sliting my wrist over this thread. There are alot of forum members who have an enormous amount of experience probably some go back to 1960's. The H lay out as it is known has been around since the introduction of fully pumped central heating systems back in the 1970's. It is the only proven method of installation which works and does not cause pumping over on an open system Ect: Give me any manufacturer boiler instructions from this time to current day and it will show this method of piping. Your labeling on the photograph is spot on.

 

[jase158]

Jase158, I thinking about sliting my wrist over this thread.

Thats a bit drastic? I was saying that i was wronge and everyone else is right,

May i just explain a couple things,
1. I have never installed a pump or a full central heating system
2. I am relatively new to plumbing, compared to some of the people on here,
But what i am saying is, just because everybody does it this way and it works this way doesn't neccessarily mean its right, although it is right this time
and isn't there any other way of doing it?

 

[jase158]

Let me just ask a question.
Where the pump connects in does it pull water as well as push the water around the system? or does it simply push the water round?
If it pushes only then obviously this is where i am getting confused, but if it pulls the water, what prevents it from pulling the water from the F and E?

 

[Reg Man]

Thanks jase158, feel better now.

The best leap forward I think, is sealed systems. They don't suffer many of the water quality problems you get on the open systems. Only draw back is the manual top up.

 

[jase158]

Thanks jase158, feel better now.

The best leap forward I think, is sealed systems. They don't suffer many of the water quality problems you get on the open systems. Only draw back is the manual top up.

Doesnt this have to be a new (ish) boiler though, Condensing type or combi? as there has to be a AAV, Expansion Vessel and PRV?

 

[Reg Man]

From post 19 Quote:The concept is worked by locating the open vent a cold feed as close together as possible (within 150mm) on the flow pipe before the pump. The reason it has to be before the pump, is that this area will be the place of the least pressure on the system therefore preventing circulation into the header cistern. Quote: