Vent pipe overflow

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Hi experts :)

When the central heating is on, the vent pipe constantly expels hot water into the top of the expansion tank in the attic. The water level maintains an equlibrium in the tank so I've been leaving it as it is. However, the situation needs sorting pretty quick as the condensation is causing a problem in the attic.

The hot water is a seperate system (I think). It's a big copper thing in a Tea crate in the hall cupboard so I've ruled that out.

other symptoms include corroded and leaking radiators, and the occasional howl of anguish from the pump/thermostat/boiler bit.

I've bled the pump and the radiators and released some water from the system on the bottom of one of the radiators.

However, the constant flow of hot water form the vent pipe into the expansion tank continues whenever the central heating is on.

Any help is much appreciated!

Thanks in advance,

Jon
 
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So, you have a tank on a tea crate, and some corroded radiators. Hmmm.....surely there are some other parts to your system, as it's Christmas, give us a clue about the pump/thermostat/boiler bit.
 
hi oilman,

the tank is 'in' the tea crate ;)

the pump is a Myson 'unit five' its in the cupboard in the corner of the lounge with the boiler which is unbranded, its small and wall mounted - the thermostat dial is on it, it has a 1-6 setting. Also there is the Timer/control unit which it would seem is a 'single channel timeswitch'. It is a flat with 7 radiators (although now 5 due to 2 being isolated after leaking incidents....!)

Have considered draining the system and refilling with some of b&q's finest.

A bit new to this, and very much appreciate your assistance, so anything else I can elaborate on to help you help me, do let me know.

Many thanks,

Jon
 
First thing to try is changing speed of pump. If flat gets warm and it stops pumping over, that's all you need to do.

I don't know that pump but most have three speeds, a turn lever which usually has an off position between each speed. Three positions, you can tell if you've slowed it down it gets quieter.

If that doesn't work come back for more suggestions.

We need a sticky on this.
 
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Hi Paul, many thanks for your suggestion,

The pump has a switch on top to change between high and low. Has been on low allready the whole time.....:(.

Incidentley, pump is definately working, you can hear/feel it and rads get hot.

Keep em coming....!

Regards,

Jon
 
Have a squint at the arrangements of pipes where the ones from the loft join the circulation. I expect you will have a 15mm feed pipe, and a 22mm vent pipe, coming down and joining a 22mm or 28mm circulation pipe. The joins may be near the pump. If so:

What is the sequence (e.g. vent pipe, 6 inch space, then feed pipe, then 6 inch space, then pump.

Also, have a look at the pump, should be an arrow on it for direction of flow, are the feed and vent pipes on the suction side or the flow side of the pump?

Also, has the installation recently been upgraded or altered?
 
Hey John, thanks so much.

The photo of the pipes I think you are referring to is here:

http://img.photobucket.com/albums/v355/KoperniK2K/250c263a.jpg

The arrow on the underside of the pump is from left to right in the photo (pointing towards the boiler).

It has not been recentley upgraded or altered - that is apart from me having shut removed one radiator in the hall and shut off one in the lounge - both due to dripping.

Thanks and regards,

Jon
 
Thanks. I can see 4 pipes coming down on the left of the picture, can you say what each of them does?

Pipes 2 and 4 (numbered from the left) look as if they are connected to the suction side of the pump, is pipe 2 15 mm and is it the coldest of all the pipes? Is it the cold feeed?

There is another 15mm pipe, (5) looks newer, going straight up in the far right of the picture, what does that do? How hot is it? Is it by any chance where the hot water is squirting out of in the loft?

There are a couple of 15mm pipes going downwards on the left of the picture, what do these do?

If you can identify which pipes are for radiators, which are for the hot water cylinder, which is the feed, and which the vent, we shold be able to puzzle this out.

Also can you lay your hands on a magnet. Copper pipes should have no attraction to it. But hold it against all the pipes, and see if there is any attraction, especially at the joints (this is a sign of iron corrosion products collecting in the pipe). Especially check 2, 4 and 5. Also identify which are the hottest and coolest pipes, and see if it varies along their length.

If i were to guess that the white-painted pipes are oldest, and the unpainted ones, and the boiler and pump, are newer, do you think I would be right? What colour is the water when you bleed a rad?

Do pipes to the radiators come up from the floor, or down from the ceiling?

How long have you lived in this flat, and when did you notice the water pumping over?

Do any of the pipes have valves on them that aren't shown, and have any of them been cut off or capped, for example in the loft?



** I am extremely suspicious of pipe 5, which is on the pressure side of the pump **
 
What is the normal level of water in the F/E tank ? If it is too high it will pump over. With the system at rest (off) you should have only just enough water in the F/E tank to cover the feed pipe at the bottom of the tank (the point is that whatever water level you have in the tank will also be the water level in the expansion pipe (gravity is a wonderful thing) so if it is high, it will take very little expansion for it to over pump). You also ideally need the highest point of the expansion pipe to be at least 12" (40cm) above the top of the tank (accomodates more expansion before pumping over). But firstly lower the water level in your tank as described above and reset your ballcock to operate at that level then let us know the results.
N.B. Over pumping also means that the system is constantly being re-oxygenated and this will corrode your rads. So fix the over pump then add an inhibitor.
 
bathjobby said:
You also ideally need the highest point of the expansion pipe to be at least 12" (40cm) above the top of the tank (accomodates more expansion before pumping over).

very good point. Can you give us a pic of the F&E tank and the vent pipe, showing us how high the bend is?
 
Thanks guys,

OK, - the water level in the F&E was very high due to a leaky ballcock, so replaced that a week ago, and drained water from the system (out a valve on the pipe near the botom corner of one of the rads) The water level is now 7-8 inches - so it is about 1/3rd full (perhaps too much still by the sounds of it..!. The water I drained was brown/black and nasty at first then after a few pintss cleared up. I will drain some more off in the first instance..maybe just scoop it straight out the tank .Point taken on the oxygenation, and indeed thats probably why Ive lost a couple of the rads allready....!

Just to note aagain, when the CH is on, the flow of water is constant out of the vent - like a tap left on at a hearty flow.

The expansion pipe is a couple of inches above the top of the tank but perhaps 9 inches abover the level of water in the tank.

Pic coming v shortly on this!

JohnD, in answer to your Q's
Pipe 5 on far right only goes down into boiler. Where it looks like it goes up, its actually a dead end after a few inches - big apols, photo dosent show that clearly - you were only too right to be suspicious!!!.
Pipes 2&4 are connected to the suction side of the pump (or the left side where the arrow on it starts). Yes Pipe 2 is the small one at 15-20mm the other 3 are all the same size of nearer 40mm.
All 4 pipes are very hot, but 4 (and perhaps 2 - but hard to tell) are slightly less hot.

There is also a pipe coming in botom of the boiler, but v hard tophotograph. edit - its just the gas, doh.

"If i were to guess that the white-painted pipes are oldest, and the unpainted ones, and the boiler and pump, are newer, do you think I would be right? What colour is the water when you bleed a rad?" = I imagine it was all fitted at the same time. Have had this flat for a couple of years, so dont know the history, but you might well be right, its curious why parts are not painted...When bleeding a rad from the top, drips of water are a little discoloured brown, but generally clear

"If you can identify which pipes are for radiators, which are for the hot water cylinder, which is the feed, and which the vent, we shold be able to puzzle this out." = thanks mate, im working on identifying which is which & will let you know.

"Do pipes to the radiators come up from the floor, or down from the ceiling? " = pipes come down from the CEILING

Cant say how long water has been pumping over, could be a long time :oops: but cant think of a specific even that may have caused it.

"Do any of the pipes have valves on them that aren't shown, and have any of them been cut off or capped, for example in the loft? " = Im on the case - also with the magnets too

MANY MANY THANKS,

Jon[/i]
 
Far too high a level in the F/E, so you can adjust that very simply (just enough to cover the feed pipe at the bottom of the tank). The expansion pipe is far too short too. Suggest you extend that up to around 18 to 24 inches above the top of the tank (not top of water level). You will find these 2 things will make a difference.
Has this always happened or just started ?
 
hi, ok, nice one, ill be taking water out the tank in a minute, ballcock wont go low enough I dont think, but maybe Ill bend it..!

Crikey yes, vent pipe is too low if it should be >18" above tank, ill look into getting it higher..ta

LINK TO F&E TANK AND VENT PIPE:

http://img.photobucket.com/albums/v355/KoperniK2K/473d5cfd.jpg

note, ive taken off the cover/insulating for the pic. Note also, that flow from the vent is constant.....oh er....!

I should add also that on the pic of the boiler & pipes in this pic from earlier http://img.photobucket.com/albums/v355/KoperniK2K/250c263a.jpg, the two pipes coming out and down to the left service just one rad a few ft away, all the other rads are serviced from the ceilings. - from 2 of those 4 vertical pipes shown earlier.

John, still working on which of the 4 verticle pipes are which, rummaged in the corner of the attic but the crucial bit to see where they go their own ways is hidden. Certainly though, two are servicing the other rads in the flat, and the other two are the vent and feed from the F&E tank. It might not help determine this but.. the pipes i mentioned going out to the left and bottom of the original pic, to the single rad: the one connecting to the lockshield valve on the rad is the same pipe 2&4 connect to, the one connecting to the open/close end of the rad is off the same pipe as 1&3.

Again thanks to all,

Regards,

Jon
 
I think i know what it is (subject to your tracking down what each pipe does).

I think pipe 2 is the cold feed from the F&E tank. I think it is unobstructed, because the overpumpimg water must be getting back down into the syst.

I think pipe 4 is the return pipe from the radiators, coming back down from the loft.

I think pipes 1 and 3 - one of them is the hot supply to the rads. the other I think is the vent pipe. Because it has been wrongly fitted on the pressured flow, not the suction, the pump is manfully pushing water up it.

If this is correct:

First you need to verify which is the vent. Then you need to connnect it to the suction side, a few inches beyond the cold feed. Also raise the vent pipe so that the bend is well above the F&E tank (it doesn't hurt to raise it as far as the roof will allow before it bends back down).

Then run the system for a while to see that it has fixed the prob.

Then drain and flush as much of the old filth out of the system as you can with plain water; then give it a flush with a chemical cleaner (If you can afford £90 to fit a Magnaclean, which traps any circulating iron corrosion sediment, which you will have got A LOT OF), do so as it will ruin your pump.

Then refill for service, including a corrosion inhibitor to stop it getting any worse.

Then look up the price of new radiators and valves to replace those that have corroded (probably all of them, but certainly the ones that are leaking). You will be doing a lot of flushing, so if you haven't already got a good drain cock, look at the rad valves with drain cocks integrated and fit a few of those to replace leaky old rad valves (like this http://www.screwfix.com/app/sfd/cat/pro.jsp?id=11074&ts=62035 edited to say, you will have to put one of these on each rad, with drop-down pipes from the ceiling, there is no other way to get the water out, but they are very cheap.


edited to say, bathjobby's idea of lowering the F&E level and raising the vent pipe are the quickest and easiest things, so do them first. If they solve the overpumping it takes the urgency off. though I think it will recur when you turn a radiator down or when your sediment causes a blockage, as the pumped water will take the path of least resistance.
 
oh, and bathjobby, I think its been happening for some time (many weeks maybe even months).

I think I mentioned before but, the boiler does howl like chwebacca for a few seconds and shudders once every several hours....from reading sounds like air in the system too...
 

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