Header Tank Gunge


Our central heating system has a separate header tank for the heating
side of the system. I had a look in said tank and found to my horror
that its has loads of slimy gunge floating in it and more stuff on the
bottom of the tank. I'm concerned it could easily block the outlet so I
intend to clean out the tank and check that the output pipe is clear.

Q:

1) How does one prevent this gunge accumulating again in the future? The
system has always had corrosion inhibitor added BTW.

2) The output pipe is a few cm above the bottom of the tank but there's
no filter or other mechanism to reduce the risk of blockage - is there a
suitable device to help?

3) The ballcock arm has been set to give only about 6cm of water depth
in the tank. Is this setting OK?

nemo Wrote in message:
Header Tank Gunge


Our central heating system has a separate header tank for the heating
side of the system. I had a look in said tank and found to my horror
that its has loads of slimy gunge floating in it and more stuff on the
bottom of the tank. I'm concerned it could easily block the outlet so I
intend to clean out the tank and check that the output pipe is clear.

Q:

1) How does one prevent this gunge accumulating again in the future? The
system has always had corrosion inhibitor added BTW.

2) The output pipe is a few cm above the bottom of the tank but there's
no filter or other mechanism to reduce the risk of blockage - is there a
suitable device to help?

3) The ballcock arm has been set to give only about 6cm of water depth
in the tank. Is this setting OK?


If the gunge is brown and forming a film inside your header tank,
then this is fairly usual in a vented system. If the gunge is
forming a crust over the tank liquid then this could be a
bacterial infection. Look at the Fernox website for a treatment
to add to the header tank.I
Personally I would turn off htg and hot water, bung up outlet hole
in header tank and clean the tank out thoroughly. Then add some
inhibitor to tank and some anti fungal treatment.
As to the level of water I believe this should be low as yours is
(but can't remember why). Just check the float valve is operating
correctly.

Hth

Phil
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In message , TheChief
writes
nemo Wrote in message:
Header Tank Gunge


Our central heating system has a separate header tank for the heating
side of the system. I had a look in said tank and found to my horror
that its has loads of slimy gunge floating in it and more stuff on the
bottom of the tank. I'm concerned it could easily block the outlet so I
intend to clean out the tank and check that the output pipe is clear.

Q:

1) How does one prevent this gunge accumulating again in the future? The
system has always had corrosion inhibitor added BTW.

2) The output pipe is a few cm above the bottom of the tank but there's
no filter or other mechanism to reduce the risk of blockage - is there a
suitable device to help?

3) The ballcock arm has been set to give only about 6cm of water depth
in the tank. Is this setting OK?


If the gunge is brown and forming a film inside your header tank,
then this is fairly usual in a vented system. If the gunge is
forming a crust over the tank liquid then this could be a
bacterial infection. Look at the Fernox website for a treatment
to add to the header tank.I
Personally I would turn off htg and hot water, bung up outlet hole
in header tank and clean the tank out thoroughly. Then add some
inhibitor to tank and some anti fungal treatment.
As to the level of water I believe this should be low as yours is
(but can't remember why). Just check the float valve is operating
correctly.

Hth

Phil

It was only yesterday that I cleaned out my CH header tank. I took the
opportunity because I'm just about to have a towel rail and a radiator
replaced, and the system will have to be partially drained.

It's years since I last cleaned it out, and there was a fair amount of
soft brown sludge on the bottom, plus a hard-ish thin brown coating on
the upper walls. There was also a sort-of thin oily film on the surface.
[It gets this way after a few years of neglect.]

To allow for the system to feed the expanded (hot) water back to the
tank, the water level is set fairly low (around 5"). This means that
there is no reason why it should (normally) ever reach the overflow
level.

There is no stop valve in the outlet pipe, so I found a tapered
champagne cork that was a perfect fit to block it up. Tying up the float
valve when required, I stirred up the sludge and took a stiff brush to
the harder coating, and repeatedly drained the tank by siphoning the
water off through a long hosepipe poked through the overflow pipe, and
going down to the ground level in back garden.

When the plumbing work is done, and the system is being refilled, I have
a tin of inhibitor (similar to Fernox) to bleed in to the outlet pipe as
things are filling up.
--
Ian

On 03/10/2015 22:49, TheChief wrote:

As to the level of water I believe this should be low as yours is
(but can't remember why). Just check the float valve is operating
correctly.


Having the water level fairly low leaves the maximum room for expansion
without any risk of overflowing.

*But* the water level must cover the outlet pipe at all times -
otherwise air will be drawn into the system. When setting the level,
bear in mind that some evaporation will take place, and assume that the
infrequently used ball valve may well fail to respond to a small change
in level. I think I would go for 5cms above the outlet pipe.
--
Cheers,
Roger
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On 03/10/2015 22:38, nemo wrote:
Header Tank Gunge


Our central heating system has a separate header tank for the heating
side of the system. I had a look in said tank and found to my horror
that its has loads of slimy gunge floating in it and more stuff on the
bottom of the tank. I'm concerned it could easily block the outlet so I
intend to clean out the tank and check that the output pipe is clear.

Q:

1) How does one prevent this gunge accumulating again in the future? The
system has always had corrosion inhibitor added BTW.

2) The output pipe is a few cm above the bottom of the tank but there's
no filter or other mechanism to reduce the risk of blockage - is there a
suitable device to help?

3) The ballcock arm has been set to give only about 6cm of water depth
in the tank. Is this setting OK?

Update
======

Thanks for the advice guys.

I tackled the job today (yeccch). Tied up the ballcock arm then used a
small plastic tub as a baler/scraper to clean out the tank. There was
about a third of a bucket of gloopy gunge. The outlet pipe connector was
hidden in gunge, so presumably at least partially blocked.

I checked that the outlet pipe was clear by slackening the connection to
the stop tap in the airing cupboard - clean water flowed.

On 03/10/2015 22:38, nemo wrote:
Header Tank Gunge


Our central heating system has a separate header tank for the heating
side of the system. I had a look in said tank and found to my horror
that its has loads of slimy gunge floating in it and more stuff on the
bottom of the tank. I'm concerned it could easily block the outlet so I
intend to clean out the tank and check that the output pipe is clear.

Q:

1) How does one prevent this gunge accumulating again in the future? The
system has always had corrosion inhibitor added BTW.

A well fitting lid helps - but its difficult to keep completely gunge
free. Inhibitor is one thing. Occasional flushing is about the only
other thing you can do.

Make sure the system does not "pump over" as this allows extra air into
the system which increases the accumulation of corrosion by products and
also algae and mould growth.

2) The output pipe is a few cm above the bottom of the tank but there's
no filter or other mechanism to reduce the risk of blockage - is there a
suitable device to help?

The height difference is designed to ensure any sediment is below the pipe.

3) The ballcock arm has been set to give only about 6cm of water depth
in the tank. Is this setting OK?

Remember its also an expansion tank, so at times the level will be
higher than the ballcock level.

--
Cheers,

John.

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On 04/10/2015 20:45, John Rumm wrote:
On 03/10/2015 22:38, nemo wrote:
Header Tank Gunge


Our central heating system has a separate header tank for the heating
side of the system. I had a look in said tank and found to my horror
that its has loads of slimy gunge floating in it and more stuff on the
bottom of the tank. I'm concerned it could easily block the outlet so I
intend to clean out the tank and check that the output pipe is clear.

Q:

1) How does one prevent this gunge accumulating again in the future? The
system has always had corrosion inhibitor added BTW.

A well fitting lid helps - but its difficult to keep completely gunge
free. Inhibitor is one thing. Occasional flushing is about the only
other thing you can do.

I'll check it periodically in future.


Make sure the system does not "pump over" as this allows extra air into
the system which increases the accumulation of corrosion by products and
also algae and mould growth.

Don't think that's happening, but I'll watch out for it.

2) The output pipe is a few cm above the bottom of the tank but there's
no filter or other mechanism to reduce the risk of blockage - is there a
suitable device to help?

The height difference is designed to ensure any sediment is below the pipe.

In this case the sediment was deeper and so covered the pipe outlet.
Possibly 20 years worth of accumulated grot.

I'm somewhat peeved because the feed pipe has actually become blocked a
couple of times, starving the system of water[1] and eventually
preventing the boiler from firing up. Each event was sorted and the pipe
cleared by plumbers who failed to clear the gunge in the tank, nor even
point out the source of the problem - presumably hoping for a repeat job
sometime later.

[1] Yes, probably a slow leak somewhere but I can't find it.


3) The ballcock arm has been set to give only about 6cm of water depth
in the tank. Is this setting OK?

Remember its also an expansion tank, so at times the level will be
higher than the ballcock level.

Good point - I've left the level as-is.