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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?
 
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?
 
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.
 
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?
 
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:
 
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?

Not necessarily. I fitted sealed systems back in the 1980's on cast iron boilers. They did have to be fitted with overheat thermostats and manufacturer would have to state it was suitable for sealed systems. The expansion vessel, PRV, Pressure gauge and filling loop were the extra bits we had to install.
 
You have a blockage, you will need a powerflush and perhaps a reconfiguration (clearly haven't seen the system). I get this all the time mate.
 
You have a blockage, you will need a powerflush and perhaps a reconfiguration (clearly haven't seen the system). I get this all the time mate.

Thanks, I have a plumber coming to powerflush the system tomorrow afternoon, in preparation of me fitting all new TRVs and a Magnaclean.

I might ask him to fit an air separator at a later date as I can't get my head around the flow & return connections.
 
Jase158, I thinking about sliting my wrist over this thread
:D:D

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?

Still got a lot of learning to do eh:)

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?

If i have time later i will draw you a couple of pictures that will help explain how it works.
 
i agree have been in many an old house with this type of layout, but it is a reconised piping method and many people still use it 2day!
 
cannot see how that system works, isnt the return joing on the positive side of the flow, how does the water get round?
 
oh its a bi pass i presume, will adding a bi pass valve help?

It is a bypass without a valve. Fitted by an eejit as it is not necessary in the first place and if he fits one, at least valve it.

If the kids don't come through i'll not be doing much tomorrow so i may explain how different systems work with a few drawings.

Clue = neutral point.
 
got to be the best post ive read.... ****ing myself here about you lot arguing over a basic layout. The layout is spot on other than the bypass needs a ABV on it. If there is water coming out the vent pipe then theres got to be a blockage not allowing the circulation hence water coming out the vent its got nowhere else to go..
 
got to be the best post ive read.... ****ing myself here about you lot arguing over a basic layout. The layout is spot on other than the bypass needs a ABV on it. If there is water coming out the vent pipe then theres got to be a blockage not allowing the circulation hence water coming out the vent its got nowhere else to go..

Totaly agree. Its basic layout, the only way to pipe up open systems over the years. I think some of the forum posts, got a little consfused.
 
It is a bypass without a valve. Fitted by an eejit as it is not necessary in the first place and if he fits one, at least valve it.

If the kids don't come through i'll not be doing much tomorrow so i may explain how different systems work with a few drawings.

Clue = neutral point.

yes tamz it is due to the neutral point, obviously punping over is under positive pressure ie, pushing not pulling, did they suss out the problem? is the pump on the right way? if it was working properly then started to fault there must be a reason. if its been like that from new or since some work was carried out then all fingers point to that!
 
just read some posts, yes i agree the layout is VIP and therefore as good as it gets, cold feed is the neutral point and therefore the vent is within the neutral zone and shouldnt pump over all else being correctr. ive seen loads of these blocked at the cold feed.

When waters hot it should expand up the cold feed, if it blocks it wont be able to expand into the F&E cistern and has to expand up the vent. then it cannot come back into the system. its not really pumping over as such but expanding over. saying its pumping over leads people to believe theres a feed and vent fault, without seeing the system in operation its hard to say but i agree cut out the tee and replace would be first check.

fuzz
 
What's going on?? What's this ancient system? They don't show this on the course.

I'll tell you what,let's rip it out and stick a combi in:p
 
The basic principles of system design are being lost due to combi's and sealed systems being more popular bit it should be important to know the basics.
There are dozens of ways to pipe a system all based on a few basic layouts.
Understanding how the position of the feed vent and pump effects the water circulation helps.
Here are a couple of drawings. (this could have been a far longer post but i have simplified a lot of things)

I'll start with this one. Basic common layout for a gravity HW, pumped heating on an old cast iron boiler.

negative.JPG

The position of the feed connection to the system is called the neutral point. Everything from the pump to the feed is under positive pressure (from the pump) and everything after the feed is negative.
In this drawing the only part of the system under positive pressure is from the pump to the boiler (as this is effectively the point the feed connects). The rest of the circuit is under negative pressure (the water is being pulled).
Because the cast iron boiler holds so much water it also acts as a neutraliser and the water flow from the pumped side slows right down so has very little effect on the gravity side.
It used to be though having the pump on the return like above would help the gravity circuit. In reality it didn't have any real effect.
A system laid out like this will not draw air or pump over (unless a blockage is introduced).

positive.JPG
Same system with the pump on the flow. The heating circuit is now under positive pressure (being pushed). This is the better pump position as pumps can push better than they pull.

Move on a few years and motorised valves are introduced and systems become fully pumped. Still using high water content cast boilers, so we get something like this.
positive fully pumped cast iron.JPG
Feed and expansion still connected to boiler so position of the pump does not cause it to pump over or draw air. Pump on the flow so the system is under positive pressure.

negative fully pumped cast iron.JPG
Same thing with pump on the return. System under negative pressure.


If you use a low water content boiler or the feed and expansion are taken from the pipework, where or how they are connected starts creating problems.
positive fully pumped.JPG
Pipe it as above and a suction effect is introduced to the expansion pipe and if the pump is set too high it will draw air. Fitted like this to a low water content boiler where the pump speed usually had to be set high this is why a lot of systems fitted in the 80's/90's are full of sludge.
Easy quick way to over come this was to combine the feed with the expansion like this
positive fully pumped feed expansion.JPG
This stopped the problem as the pump had to pull water from the F&E tank rather than air. It was not ideal though.

So they developed this system
close prox f and e.JPG
Provided the feed and expansion tees were kept within 150mm of each other, the pump would have very little effect on the expansion pipe. Go much beyond the 150mm spacing and it will pump over.

There are dozens of variations of these layouts. Just think how the position of the feed and expansion will effect the system or introduce blockages and think what would happen.

A bit quickly explained and i have missed out a lot but the basic principals are shown. Hope this is of some use to someone.
 
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What's going on?? What's this ancient system? They don't show this on the course.

I'll tell you what,let's rip it out and stick a combi in:p

They don't show much on the courses because they probably don't fkn know. Combi is the answer to everything:D
 
yuve too much time on yer hands tamz!!! lol
youve pretty much said what i said but with more background, i agree alot of newbies tend to favour combis as its all they know. i dont think its the tutors who are at fault, lazy and/or semi skilled plumbers are
 
" i dont think its the tutors who are at fault, lazy and/or semi skilled plumbers are"

don't think you were born skilled .....every one deserves a chance and every one who wants to become pro will go through anything to become pro !!!

Thank you for your time TOM !!!!
 
Gents,
New to this so please be gentle.

I have tonight noticed a small amount of warm water spurting out of the vent / overflow pipe into the FE tank when the pump turns off, in water or heating position. Not a lot less than half an egg cup. Only noticed when overflow started dripping outside.
Looking at the vent pipe outlet which was under water its been there a while. (Blue colour)
I have just recently removed and refilled a radiator during decorating. About a week ago.
I have some brown sediment in the tank but whole system is only 10 years old.
I have read the thread and the position of the neutral pipework looks about right.
What height should the overflow/vent pipe invert be above the water level in the tank?
Mines about 4-5 inches. I have seen 18 inches quoted elsewhere but the boiler installation manual says nothing.
When the pump runs I can see a gentle wafting backwards and forwards of sediment around the FE tank outlet.

Any help/advice/sympathy would be gratefully received.
Horse
 
dear horse,
first you need some one to see it or picture would help . you have corrosion starting in your system (luck of having inhibitor) ! have you had any air in your radiators lately any cold spots ?
 
If the Vent pipe is discharging back into the F&E Tank but the water level doesn't rise high enough to reach the Warning Pipe and discharge outside then the Cold Feed from the F&E to the Hot Water Cylinder won't be blocked. The water level in the F&E should be 1/3 full when cold to allow for expansion when everything gets hot. The level should however be above the Cold Feed. The arm of the Ball Valve can be bent down to achieve this. The Cold Feed and Vent Pipe should be as close together behind the CH Pump to encourage Negative Pressure. The boiler could be boiling the water and the Vent doing it's job. The Boiler has a thermostat which can fail and could be checked by a plumber to see if this is funtioning correctly. The Vent Pipe should rise at least 450mm above the F&E and back down in a big arc, to prevent any surge effects - hope this helps
 
dear horse,
first you need some one to see it or picture would help . you have corrosion starting in your system (luck of having inhibitor) ! have you had any air in your radiators lately any cold spots ?

Thanks for the response. I will get some pictures and post. I have no cold spots and the recently removed radiator only had a little black sludge in it. I have had a little air 'single wooshing' in the system recently, twice I have heard it, in the last month. I fitted an auto bleed valve on the radiator in the bathroom (did it as it was a new tall ladder type radiator, over a year ago) I have not had a problem with air in any radiators since. I would add at present the vent pipe outlet is below the overflow level, so when I noticed it today the pipe was 1 inch under water. Have checked the thermostat and it is operating fine. Also it does this in CH a only as well as Hot Water. Again thanks. Horse
 
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If you turn everything off and leave to cool, drain a bucket of water from the CH system via a Drain Valve on the Ground Floor with a Hose, does the level in the F&E drop? This will test for a blockage where the Cold Feed tees into the circuit and the only way expanded water can escape is through the Vent Pipe...this is quite common
 
Looks from them pics like it's piped up correctly few things i would look at ; Pump the right way round, is there enough head above the pump(2m), flow and returns the right way round.
 
Hi
Thanks for reply the tank did overflow. Well dripped so blocked feed a possibility. As soon as I can( work commitments) I will try your drain refill test and get back. I will change the vent pipe height and arc as well. Thanks for staying with me on this. I will post as soon as I can.
Horse.
 
Raise the vent to around 450 above the F&E and take it out of the water. Bend the ballcock down a bit to reduce the fill level and bail some water from the tank.
 
and get some local plumber to power flush you heating and put inhibitor before is to late
 
Hi,

The plumber let me down on Friday but should be coming Thursday to powerflush my system.
Whilst it's drained I'm going to do a few modifications to the pipework to try to rectify the problems I've been having.

I've finally worked out how to best fit an Aerjec to my system, I'm also going to replace all my leaky or old TRV's, and extend my vent pipe a little bit.

The ballcock has been bent down a bit and I've bailed out about 15 litres from my F&E tank (Feed & Expansion :confused: ).

Finally, could someone please give me a BES part number of a good quality bypass valve to fit into my vertical 15mm bypass pipe?

Thanks,
Mark.
 
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Easiest way to fix - convert to sealed system. The hours spent on determining the problem which may not be easily fixable would best be put to converting it over.

Do not leave it. Every time you draw air in will encourage rapid corrosion of the radiators, or lose water through the overflow will dilute any rust inhibitor.

shouldnt be hard to find, think converting is an expensive cop out
 
Hi,

The plumber let me down on Friday but should be coming Thursday to powerflush my system.
Whilst it's drained I'm going to do a few modifications to the pipework to try to rectify the problems I've been having.

I've finally worked out how to best fit an Aerjec to my system, I'm also going to replace all my leaky or old TRV's, and extend my vent pipe a little bit.

The ballcock has been bent down a bit and I've bailed out about 15 litres from my F&E tank (Feed & Expansion :confused: ).

Finally, could someone please give me a BES part number of a good quality bypass valve to fit into my vertical 15mm bypass pipe?

Thanks,
Mark.
its a common componentglad your sorting the problem, blocked feed is most probable
just ask at your local plumbing merchant for an auto bi pass,
 
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