Hi all

As I was out-and-about, I thought it worthwhile to do a circuit of the house
and see if anything looked awry.

The old ticker sank when I saw a long icicle hanging from one of the
overflows from the loft.
So I went up in the loft to investigate and discovered that the icicle was
hanging from the CH header tank overflow, rather than the main water store
tank(s).
Lifting the (somewhat improvised) lid I found that the level in the tank was
fine and that the float valve appeared to be sealing securely.

As this tank runs fairly warm, I reach the (hopeful) conclusion that the
water escape/icicle is down to condensation in the overflow pipe (approx
1.5m long) rather than a failure.

Anyone else with a similar issue in these conditions?
[In east yorkshire, where snow and ice are prevailing currently]

Phil

On Nov 29, 4:50*pm, "TheScullster" wrote:
Hi all

As I was out-and-about, I thought it worthwhile to do a circuit of the house
and see if anything looked awry.

The old ticker sank when I saw a long icicle hanging from one of the
overflows from the loft.
So I went up in the loft to investigate and discovered that the icicle was
hanging from the CH header tank overflow, rather than the main water store
tank(s).
Lifting the (somewhat improvised) lid I found that the level in the tank was
fine and that the float valve appeared to be sealing securely.

As this tank runs fairly warm, I reach the (hopeful) conclusion that the
water escape/icicle is down to condensation in the overflow pipe (approx
1.5m long) rather than a failure.

Anyone else with a similar issue in these conditions?
[In east yorkshire, where snow and ice are prevailing currently]

Phil

It could well be condensation if the header tank is warm. However it
should not be warm. If it is, there is a defect in you heating system
that needs attention.

In message
,
harry writes
On Nov 29, 4:50*pm, "TheScullster" wrote:
Hi all

As I was out-and-about, I thought it worthwhile to do a circuit of the house
and see if anything looked awry.

The old ticker sank when I saw a long icicle hanging from one of the
overflows from the loft.
So I went up in the loft to investigate and discovered that the icicle was
hanging from the CH header tank overflow, rather than the main water store
tank(s).
Lifting the (somewhat improvised) lid I found that the level in the tank was
fine and that the float valve appeared to be sealing securely.

As this tank runs fairly warm, I reach the (hopeful) conclusion that the
water escape/icicle is down to condensation in the overflow pipe (approx
1.5m long) rather than a failure.

Anyone else with a similar issue in these conditions?
[In east yorkshire, where snow and ice are prevailing currently]

Phil

It could well be condensation if the header tank is warm. However it
should not be warm. If it is, there is a defect in you heating system
that needs attention.

Doesn't the CH header tank act as an expansion tank for when the heating
cycles from off (coldish) to on (hot)? This causes the water to expand
and contract and, as it expands, some warm water finds its way back into
the header tank.

I'm pretty sure that my header tank does get somewhat warm, and, in
frosty weather, wisps of 'steam' can sometimes be seen outside, coming
from the overflow pipe (protruding, just under the eaves of the roof).
This happens mainly soon after the CH has fired up after having been off
overnight. As the top of the tank is covered (but not tightly sealed),
any hot water in it will tend to produce 'steam' at the overflow.
However, I don't think it has ever produced icicles - possibly because,
in the cold weather, I usually leave the CH on overnight, turned down a
few degrees.
--
Ian

On Nov 29, 8:57*pm, Ian Jackson
wrote:
In message
,
harry writes





On Nov 29, 4:50 pm, "TheScullster" wrote:
Hi all

As I was out-and-about, I thought it worthwhile to do a circuit of the house
and see if anything looked awry.

The old ticker sank when I saw a long icicle hanging from one of the
overflows from the loft.
So I went up in the loft to investigate and discovered that the icicle was
hanging from the CH header tank overflow, rather than the main water store
tank(s).
Lifting the (somewhat improvised) lid I found that the level in the tank was
fine and that the float valve appeared to be sealing securely.

As this tank runs fairly warm, I reach the (hopeful) conclusion that the
water escape/icicle is down to condensation in the overflow pipe (approx
1.5m long) rather than a failure.

Anyone else with a similar issue in these conditions?
[In east yorkshire, where snow and ice are prevailing currently]

Phil

It could well be condensation if the header tank is warm. However it
should not be warm. *If it is, there is a defect in you heating system
that needs attention.

Doesn't the CH header tank act as an expansion tank for when the heating
cycles from off (coldish) to on (hot)? This causes the water to expand
and contract and, as it expands, some warm water finds its way back into
the header tank.

I'm pretty sure that my header tank does get somewhat warm, and, in
frosty weather, wisps of 'steam' can sometimes be seen outside, coming
from the overflow pipe (protruding, just under the eaves of the roof).
This happens mainly soon after the CH has fired up after having been off
overnight. As the top of the tank is covered (but not tightly sealed),
any hot water in it will tend to produce 'steam' at the overflow.
However, I don't think it has ever produced icicles - possibly because,
in the cold weather, I usually leave the CH on overnight, turned down a
few degrees.
--
Ian- Hide quoted text -

- Show quoted text -

Yes it does allow for expansion. But the expansion is not sufficient
to warm the tank, only talking a few cc's at most and then only as
temperature rises.

The most likely explanation is that the system is "pumping over". Ie
when the pump is running it's forcing water up the expansion pipe into
the tank.
BTW the tank should only have a few inches of water into bottom of it,
it should not be full. The expansion pipe should be well clear of the
water surface. This occasionally happens temporarily to a pipe
freezing in the system somewhere.

A couple of other possible explanations a-
A leak in the heat exchanger in your hot water cylinder allowing water
to pass from hot water system into the heating system.
The boiler has overheated for some reason and steam/ho****er has come
up the expansion pipe. (Boiler thermostat and/or pump failure.)

On Mon, 29 Nov 2010 22:57:04 -0800 (PST), harry wrote:

Yes it does allow for expansion. But the expansion is not sufficient
to warm the tank, only talking a few cc's at most and then only as
temperature rises.

Coefficient of expansion for water 0.00021 per C. (ish)...

20 to 70C = 50C so that is a 0.0105 volume increase. 1 cu m of water
is 1,000,000 cu cm = 10,500 cu cm expansion or 10.5l... Now I doubt
'yer average 3 bed semi heating primary has a cu m of water in it,
maybe 1/4 of a cu m but we are still looking at 2.5l (2,500 cu cm) of
expansion. Rather more than a "few cc".

I know when I put in a new expansion tank here it needed more than
the normal 10 gallon one. Think I put in 25 gallon and the level in
that varies about a foot hot to cold. This is a big system though,
there are 12 gallons of water in the boiler alone...

--
Cheers
Dave.

In message o.uk, Dave
Liquorice writes
On Mon, 29 Nov 2010 22:57:04 -0800 (PST), harry wrote:

Yes it does allow for expansion. But the expansion is not sufficient
to warm the tank, only talking a few cc's at most and then only as
temperature rises.

Coefficient of expansion for water 0.00021 per C. (ish)...

20 to 70C = 50C so that is a 0.0105 volume increase. 1 cu m of water
is 1,000,000 cu cm = 10,500 cu cm expansion or 10.5l... Now I doubt
'yer average 3 bed semi heating primary has a cu m of water in it,
maybe 1/4 of a cu m but we are still looking at 2.5l (2,500 cu cm) of
expansion. Rather more than a "few cc".

I know when I put in a new expansion tank here it needed more than
the normal 10 gallon one. Think I put in 25 gallon and the level in
that varies about a foot hot to cold. This is a big system though,
there are 12 gallons of water in the boiler alone...

Of course, there's also simple convection. Some of the hot water from
'down below' is bound to find its way up to the header tank.
--
Ian

Dave Liquorice wrote:

On Mon, 29 Nov 2010 22:57:04 -0800 (PST), harry wrote:

Yes it does allow for expansion. But the expansion is not sufficient
to warm the tank, only talking a few cc's at most and then only as
temperature rises.

Coefficient of expansion for water 0.00021 per C. (ish)...

20 to 70C = 50C so that is a 0.0105 volume increase. 1 cu m of water
is 1,000,000 cu cm = 10,500 cu cm expansion or 10.5l... Now I doubt
'yer average 3 bed semi heating primary has a cu m of water in it,
maybe 1/4 of a cu m but we are still looking at 2.5l (2,500 cu cm) of
expansion. Rather more than a "few cc".

Perhaps instead of a few cc he meant a few cm. If the footprint of the
tank is (say) 40cm x 30cm, that's 1200 sq cm, so adding 2500 cu cm to
that will raise the level in the tank by only about 2cm.