Water flowing up into Central Heating header tank (!)

[petes]

I wonder if anyone has any advice on this.... We have an (old) central heating system (heating pumped, hot water gravity) which we're going to replace later in the year when we re-do the kitchen. However, it's recently developed a problem. It's not a sealed system, and we see to have water flowing up into the header tank, and from there out of the overflow. It's a fast drip out of the overflow when the system's running, but stops when it's not. I've been up in the loft, and I'm sure the water's coming up from below rather than it being a dripping ballcock etc.. Doesn't sound good to me. Anyone got any ideas - where's the water coming from! It's been doing it a couple of months, but it getting gradually worse. I don't want to spend loads of money fixing it as I intend to throw the whole thing out in about 6 months.

Thanks

pete S

 

[seco services]

sludge is a most likely cause. is the f/e tank sludgey in the bottom of tank.
but can be many other causes

 

[JohnD]

You say it has only recently started to happen, so it is probably not (just) system design but a gradual event like corrosion, sludge or internal leak.

a few easy steps:

adjust the ballcock in the F&E so that water level is only a couple of inches above the feed pipe near the bottom, and bale out the water to this level. Verify that the valve is not dripping by holding a jar under it. Fit a new valve if you have any doubt.

Sit up there and watch it, while the system is running and no-one is operating any taps. Tie up the ball-cock in the cold water storage tank (or preferably turn off the main stop-cock) as well, and carefully note its water level.

observe if the level in the F&E rises.

If so, observe the cold water tank and observe if the water level has dropped by the same amount of gallons as the F&E has risen. If so

If not, just and turn down the speed of the circulating pump. Tell us when the system last had inhibitor added, what colour the sludge is in the F&E and how much there is, what colour the water is when you bleed the radiators. the overflow will have washed out any inhibitor, so you will need to use a cleaner and inhibitor, as you will now have even more corrosion than you did before.

But tell us the results of your investigation first.

 

[petes]

sludge is a most likely cause. is the f/e tank sludgey in the bottom of tank.
but can be many other causes

Hmm - a bit of sludge, but not loads. There's also some "slime" attached to the outlet (or in this case inlet). That's how I can tell water's coming into the tank from their - I can see the slime moving with the flow.

If it is sludge, how severe does it need to be to cause the problem and how do I got about fixing it? Not sure how many "circuits" there are involved here from the boiler, but I know the radiator "circuit" was fully drained last year, so I guess it would perhaps be the hotwater to the tank one? Does that make sense? Not sure what impact sludge has - I understand electrics much better than I do plumbing.....

Thanks

 

[seco services]

when you say inlet/outlet/
do you mean its filling the tank from the feed in the bottom of tank or from the vent pipe over the top of the tank

 

[JohnD]

There's also some "slime" attached to the outlet (or in this case inlet). ..

don't understand that, can you post a pic when you tell us the result of your investigation?

there are two or three probable causes, we won't know which it is until you investigate.

//www.diynot.com/forums/viewtopic.php?t=129539

sludge causes high resistance in the intended circuit, so the flow then travels up alternative paths.

 

[diverdee]

have u had a new pump fitted lately ? if it a bad desighn system the pump needs to run slow or can back fill tank and suck air down expansion pipe. tyr turning pump down

 

[petes]

when you say inlet/outlet/
do you mean its filling the tank from the feed in the bottom of tank or from the vent pipe over the top of the tank

Sorry - an sorry attempt at humour. I mean the feed in the bottom of the tank. My meaning was that it should be in the outlet, but it's currently the inlet instead (since that's where it's filling from )

I'll give the various advice a try and report back. Many thanks.

 

[petes]

Inhibitor was last added about a year ago - we changed some radiators and so the system was drained right down for that.

 

[seco services]

you may need to try a sludge chemical.

sentinel x800

 

[JohnD]

I think so too, but he may have a pinholed coil. We won't know until he investigates.

I bet he doesn't own a powerflusher though, so maybe not X800.

 

[petes]

OK, so this isn't looking great, but not 100% conclusive. Firstly, attached are some picture (sorry for the quality - not the easiest things to take pictures of). You see the slude and the outlet, and the final one tries to show the stuff surrounding the outlet, which visibly "blows" inwards when the tank's filling by that route.

So, a couple more details and some more research. Firstly, I didn't mention that the tank has a coil from some solar panels (yikes, yet more expense! - fitted by the previous owner). I noticed yesterday that the tank overflows if the panels are heating the water, even if the heating circulation pump isn't running (which sounds bad).

I emptied the F&E tank earlier as described, and it certainly isn't filling from the valve. As I mentioned, you can actually see the stuff around the outlet "blowing" into the tank as it fills and see the slight warmth in the water (or something in the water at least) as it comes into the tank.

The level in the cold water tank dropped a little, but only a very little (maybe .5cm ) so it was dificult to be 100% certain, but this was probably because the system wasn't misbehaving by the time I was able to do it - i.e. the water in the tank was hot and the solar panels weren't heating. However, if the water isn't coming from the valve, where else could it be coming from (other than the mentioned leak).

So, the overflow seems to happen when the hot water is heating, either by the boiler or by the panels. I guess it could be that the normal "expansion" route is blocked, and it expands into the f&e tank as the hot water expands, and then as it cools it refils from the valve. Might that make sense (or is it £££££ time).

Is the degree of gunge in the pictures indicitive of something bad - don't really know if thats alot or not.

Thanks again

pete S

Images are at //www.diynot.com/network/petes/albums/407

 

[ollski]

Surely just a holed coil in the cylinder

 

[Agile]

I bet he doesn't own a powerflusher though, so maybe not X800.

You dont need a power flushing pump to use X800.

Its just a days work as opposed to a month!

Tony

 

[JohnD]

The test with the water level in the cold water cistern will prove it

unless there is some other supply to the solar panel circuit

Lowering the water level in the F&E as I mentioned earlier will give increased room for expansion so should deal with that alternative.

I can't tell how deep the brown sludge is, but I always like to bale it out.

I am just a householder.

p.s. the correct and normal rout for expansion is up thet pipe and into the F&E.

the E in F&E stands for Expansion. So it must be empty enoigh to receive it without overflowing.