Dirty water in central heating tank in loft

Hi, I was hoping someone can give me some advice. I have a normal central heating system, two tanks in the loft, a hot water cylinder. Motorised valve etc.

The house is only 10 years old, central heating plumbed using 10mm plastic barrier piping (I hope!!) I am the second owner of the house.
Problem: One of the bathroom radiators kept getting air in it. So I kept bleeding it. Got fed up with this so got some plumbers round to see what the problem might be.
All mentioned a power flush and fitting an AERJEC.

Had this done. No air in system, but the water in the small central heating tank in the loft
Is always kind of brown/red. Never clear.

I removed all the water from the tank, cleaned it, left a container under the vent pipe to see if it was pumping over, it is not. Left the tank bone dry, to say what was happening.

Somehow there appears to be small amount of water coming back into the tank from the “outlet” of the tank. Central heating pump speed set to three.

Now I have had some plumbers around again. One guy says I should seal the system, put and pressure vessel in and fit a Maga Clean Filter in. But mentioned that the pressure will drop a couple of times in the years and should be top up.

Well if the system is sealed and there are no leaks, way should the system need topping up??

The other guy thinks I have some non barrier pipe used which is introducing oxygen into the central heating water from somewhere after the heating as reached 65degrees C. And to live with the problem and to flush out the central heating system every couple of years. Other than that, to check all the central heating pipes or to re-plumb the whole central heating system again

Sorry about the long explanation but can someone help me out. I have already spent nearly £900 pounds.
Thanks

All mentioned a power flush and fitting an AERJEC.

Had this done. No air in system, but the water in the small central heating tank in the loft
Is always kind of brown/red. Never clear.

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yeah no inhibitor in system

Somehow there appears to be small amount of water coming back into the tank from the “outlet” of the tank. Central heating pump speed set to three.

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normal when the pump stops

Now I have had some plumbers around again. One guy says I should seal the system, put and pressure vessel in and fit a Maga Clean Filter in. But mentioned that the pressure will drop a couple of times in the years and should be top up.

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why

Well if the system is sealed and there are no leaks, way should the system need topping up?? icon_cry.gif

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because a sealed system is not totally sealed

KevPlumb thank you for your reply.
In my old house. The water in the small tank in the loft was always clean.
My friends house who setup is very similar the water in the small central heating tank in the loft is clean.

Inhibitor was put in on both ocassions after the power flush.

So way is water pumping back into the tank??

Thank you for your advice.

ukzmisr said:

So way is water pumping back into the tank??

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Are you sure it's pumping back into the tank? The water in the system will expand as it heats up, that's why the feed and expansion tank is there. If there's dirty water in the system, which there probably will be if the header tank is/was dirty, it'll just expand back into the tank when the system is hot.

I would advise that you don't run the boiler with the header tank dry, otherwise you're only going to introduce even more air into the system.

What I can't explain is why the water is still dirty after the system has been flushed, unless the flush wasn't carried out properly in the first place. I hope you didn't pay £900 for just the flush and AERJEC?

Electronicsuk,
The water in the tank in the loft was emptied and cleaned after each power flush. The water is diffintely coming up through the output, since I placed a cup under the overflow, this was empty.

I did pay the said amount. But this as not fixed the problem. Hence trying to get some advise.

So any ideas why it is pumping into the expansion tank.

Now that I have found where the dirty water is coming from, I have filled the tank in the loft up with water.

ukzmisr said:

Electronicsuk,
The water in the tank in the loft was emptied and cleaned after each power flush. The water is diffintely coming up through the output, since I placed a cup under the overflow, this was empty.

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As I said before, if you emptied the tank when the system was cold, then the water would have expanded back into the tank via the feed pipe as soon as the system started to warm up.

If it's happening with the system water cold and the pump is running, it could indeed have something to do with pumping over as you have already mentioned yourself, although this term usually refers to water escaping through the vent pipe. Either way, it could point to a badly piped up system, or large amounts of dirt and crud still trapped within the system, despite the flushing.

ukzmisr said:

I did pay the said amount. But this as not fixed the problem. Hence trying to get some advise.

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Wasn't British Gas by any chance?

ukzmisr said:

So any ideas why it is pumping into the expansion tank.

Now that I have found where the dirty water is coming from, I have filled the tank in the loft up with water.

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Sorry, no more ideas from me - I'm an electrician by trade, not a plumber, I just pop in here every now and then to see if I can pick up a few tips and tricks for my DIY efforts.