Just had a plumber out to look at a CH/hot water problem. Lots of air
in the system, some rads need bleeding every day, no hot water. His
diagnosis is that it looks like a leak in the system, i.e you can't
have that much air in without water going out. The F&E level stays
fairly constant. He has turned off the supply to the F&E cistern which
I will check for a day to see if the level drops. The I will turn the
supply back on.

Anyway, if there is a leak its likey to be ground floor as there are
no signs on downstairs ceilings or anyware else. My floors downstairs
are *floating* ie, chipboard laid on a polystyrene like substance
which then lies on a concrete sub floor.

So my question, which I'm almost afraid to ask, will my floors have to
come up. Would the pipes be buried in the concrete or just laid under
the floor boards.

Is there any diagnostics that they can you to check for leaks without
destroying my entire gound floor. I know there are leak seal compounds
which can be added to the system, are they any good.

I am now sh**ing myself at the possible cost of this.

All comments welcome.

Peter

Peter Hawkins wrote:
Just had a plumber out to look at a CH/hot water problem. Lots of air
in the system, some rads need bleeding every day, no hot water. His
diagnosis is that it looks like a leak in the system, i.e you can't
snip
Anyway, if there is a leak its likey to be ground floor as there are
no signs on downstairs ceilings or anyware else. My floors downstairs
are *floating* ie, chipboard laid on a polystyrene like substance
which then lies on a concrete sub floor.

So my question, which I'm almost afraid to ask, will my floors have to
come up. Would the pipes be buried in the concrete or just laid under
the floor boards.

Is there any diagnostics that they can you to check for leaks without
destroying my entire gound floor. I know there are leak seal compounds
which can be added to the system, are they any good.

I am now sh**ing myself at the possible cost of this.

Sorry.
If the pipes are buried in the concrete (a possibility) and have not been
treated appropriately, but just buried directly, which is also a possibility,
there may not be any point in finding 'the' leak.
As the pipes will have been corroding all along their length, and if you
fix all the holes now, you're still going to need to fix next months holes.

So, if this is the case, you may be looking at replacing all the pipes.



If this is the case, I'd be looking into removing skirting board, and seeing
if I could put new pipes behind that, rather than in the floor, and totally
ignoring old pipes, just reconnecting all the rads to the new pipe.

Routing a channel in the skirting board (in the back) could mean you'd only
need a 15mm channel in the wall behind. (for 22mm)
Would you be DIYing?

Lots of air
in the system, some rads need bleeding every day, no hot water.


I'm surprised he said it must be a leak, as it could just be sucking
air in at the header tank. There are 2 pipes to the header tank, if it
ends up sucking air in via the one above the water line, this is what
happens.

Now if you had a leak, firstly air would not get in at the leak site,
since it would always be under positive pressure, so the air would only
come from air dissolved in the fresh water topping up the system. With
daily bleeding needed, thats a hell of a lot of top up water. IOW if it
was from a leak I reckon you'd be flooded by now.
So, you can stop worrying about your floor.

NT

On 21 Jan 2005 04:36:21 -0800, wrote:

Lots of air
in the system, some rads need bleeding every day, no hot water.


I'm surprised he said it must be a leak, as it could just be sucking
air in at the header tank. There are 2 pipes to the header tank, if it
ends up sucking air in via the one above the water line, this is what
happens.

Now if you had a leak, firstly air would not get in at the leak site,
since it would always be under positive pressure, so the air would only
come from air dissolved in the fresh water topping up the system. With
daily bleeding needed, thats a hell of a lot of top up water. IOW if it
was from a leak I reckon you'd be flooded by now.
So, you can stop worrying about your floor.

NT

I had considered that too, I mean water exiting under from a pumped
system should not allow air in. The following concern me:

1. There is NO vent pipe over the F&E cistern, just a mains in and
feed to system out, so I'm not sure where the air would be sucked in.

2. Air in means water is going somewhere, the level in the F&E isn't
rising, could the boiler be faulty, and boiling it off.

The system I have looks like diagram in the following link:

http://www.fortbaxter.demon.co.uk/heating.jpg


Peter

On 21 Jan 2005 11:46:59 GMT, Ian Stirling
wrote:

Peter Hawkins wrote:
Just had a plumber out to look at a CH/hot water problem. Lots of air
in the system, some rads need bleeding every day, no hot water. His
diagnosis is that it looks like a leak in the system, i.e you can't
snip
Anyway, if there is a leak its likey to be ground floor as there are
no signs on downstairs ceilings or anyware else. My floors downstairs
are *floating* ie, chipboard laid on a polystyrene like substance
which then lies on a concrete sub floor.

So my question, which I'm almost afraid to ask, will my floors have to
come up. Would the pipes be buried in the concrete or just laid under
the floor boards.

Is there any diagnostics that they can you to check for leaks without
destroying my entire gound floor. I know there are leak seal compounds
which can be added to the system, are they any good.

I am now sh**ing myself at the possible cost of this.

Sorry.
If the pipes are buried in the concrete (a possibility) and have not been
treated appropriately, but just buried directly, which is also a possibility,
there may not be any point in finding 'the' leak.
As the pipes will have been corroding all along their length, and if you
fix all the holes now, you're still going to need to fix next months holes.

So, if this is the case, you may be looking at replacing all the pipes.



If this is the case, I'd be looking into removing skirting board, and seeing
if I could put new pipes behind that, rather than in the floor, and totally
ignoring old pipes, just reconnecting all the rads to the new pipe.

Routing a channel in the skirting board (in the back) could mean you'd only
need a 15mm channel in the wall behind. (for 22mm)
Would you be DIYing?


Not DIY'ing. The boiler is in the garage, where the pipes go into the
concrete they are insulated in the standard foam tubing, I assume then
that this would be used throughout.

On Fri, 21 Jan 2005 11:15:14 +0000, Peter Hawkins
wrote:

Just had a plumber out to look at a CH/hot water problem. Lots of air
in the system, some rads need bleeding every day, no hot water. His
diagnosis is that it looks like a leak in the system, i.e you can't
have that much air in without water going out. The F&E level stays
fairly constant. He has turned off the supply to the F&E cistern which
I will check for a day to see if the level drops. The I will turn the
supply back on.

Anyway, if there is a leak its likey to be ground floor as there are
no signs on downstairs ceilings or anyware else. My floors downstairs
are *floating* ie, chipboard laid on a polystyrene like substance
which then lies on a concrete sub floor.

So my question, which I'm almost afraid to ask, will my floors have to
come up. Would the pipes be buried in the concrete or just laid under
the floor boards.

Is there any diagnostics that they can you to check for leaks without
destroying my entire gound floor. I know there are leak seal compounds
which can be added to the system, are they any good.

I am now sh**ing myself at the possible cost of this.

All comments welcome.

Peter

I'm far from being an expert, but there are devices you can get to
connect your pipework to a car foot pump to do a pressure test, but
that relies on you sealing the system at some point, otherwise the air
will eventually just bubble up through the vent pipe. These cost
around 20 quid. I'm sure other more experienced people here will
comment on these.

BTW, pipe and fittings cost next to nothing, and making joints is very
easy at least in easily accessible pipe. If you don't diy, labour
would be the main cost I would think.

Markus

Markus Splenius wrote:
.... snipped

I'm far from being an expert, but there are devices you can get to
connect your pipework to a car foot pump to do a pressure test,

.... snipped

That sounds like a b***dy good idea. I need to do some plumbing which
will then be "built-in" before I can test it with water - it would be
good to be able to do an air pressure test. Does anyone have any more
info? (although I guess it's an easy enough thing to lash together)
Presumably the necessary volume of air would be a problem.

--
Dave S
(The return email address is a dummy)

Try if possible to turn down your pump ( some have 3 settings ) If it is on
3 it can suck air into the system.



"Peter Hawkins" wrote in message
...
On 21 Jan 2005 04:36:21 -0800, wrote:

Lots of air
in the system, some rads need bleeding every day, no hot water.


I'm surprised he said it must be a leak, as it could just be sucking
air in at the header tank. There are 2 pipes to the header tank, if it
ends up sucking air in via the one above the water line, this is what
happens.

Now if you had a leak, firstly air would not get in at the leak site,
since it would always be under positive pressure, so the air would only
come from air dissolved in the fresh water topping up the system. With
daily bleeding needed, thats a hell of a lot of top up water. IOW if it
was from a leak I reckon you'd be flooded by now.
So, you can stop worrying about your floor.

NT

I had considered that too, I mean water exiting under from a pumped
system should not allow air in. The following concern me:

1. There is NO vent pipe over the F&E cistern, just a mains in and
feed to system out, so I'm not sure where the air would be sucked in.

2. Air in means water is going somewhere, the level in the F&E isn't
rising, could the boiler be faulty, and boiling it off.

The system I have looks like diagram in the following link:

http://www.fortbaxter.demon.co.uk/heating.jpg


Peter

On Fri, 21 Jan 2005 15:40:50 +0000 (UTC), "ski"
wrote:

Try if possible to turn down your pump ( some have 3 settings ) If it is on
3 it can suck air into the system.

The pump is already on 1.

In article .com,
writes:
Lots of air
in the system, some rads need bleeding every day, no hot water.


I'm surprised he said it must be a leak, as it could just be sucking
air in at the header tank. There are 2 pipes to the header tank, if it
ends up sucking air in via the one above the water line, this is what
happens.

Now if you had a leak, firstly air would not get in at the leak site,
since it would always be under positive pressure, so the air would only

Oh-err, this is wrong. Air will normally enter a heating system through
leaks, even when the water is under pressure. Air will leak into the
heating system until the partial pressure of the air in the water (or
rather the individual components of air) are the same as atmospheric
pressure. Due to the water in a heating system being repeatedly heated
and cooled, which changes the solubility of air forcing it out of
solution to collect at high points when the water is hot, as the water
cools the partial pressure of air in solution will drop. There's about
a factor of 2 between the amount of air which can dissolve at room
temperature and at max radiator temperature, so when the demand for
heat stops and the system cools down, an air molecule just outside the
leak sees a 50% vacuum inside the heating system, and gets sucked in,
even though the water pressure is above air pressure. Next time the
water is heated up, the solubility of the air drops and it gets forced
out of solution to collect at the high points again.

Now it may well be that air is collecting in the OP's system faster
that it is likely to leak in when the system cools, but it certainly
isn't the case that air can't leak in just because the water pressure
is higher. Also, because air is very much less viscous that water, it
could leak into the heating system faster than the water leaks out
through the same hole.

Of course, air entering a system by any means will quickly use up the
inhibitor too. This can result in corrosion and production of hydrogen
to add to the gasses which collect at high points.

--
Andrew Gabriel

"Peter Hawkins" wrote in message
...
Just had a plumber out to look at a CH/hot water problem. Lots of air
in the system, some rads need bleeding every day, no hot water. His
diagnosis is that it looks like a leak in the system, i.e you can't
have that much air in without water going out. The F&E level stays
fairly constant. He has turned off the supply to the F&E cistern which
I will check for a day to see if the level drops. The I will turn the
supply back on.

Anyway, if there is a leak its likey to be ground floor as there are
no signs on downstairs ceilings or anyware else. My floors downstairs
are *floating* ie, chipboard laid on a polystyrene like substance
which then lies on a concrete sub floor.

So my question, which I'm almost afraid to ask, will my floors have to
come up. Would the pipes be buried in the concrete or just laid under
the floor boards.

Is there any diagnostics that they can you to check for leaks without
destroying my entire gound floor. I know there are leak seal compounds
which can be added to the system, are they any good.

I am now sh**ing myself at the possible cost of this.

All comments welcome.

I once found a leak under the floor of an office block in Leeds by putting a
big dose of Fernox MB1 into the system and waiting till one of the denizens
reported an unusual smell.

In an earlier contribution to this discussion,
Dave wrote:

Markus Splenius wrote:
... snipped

I'm far from being an expert, but there are devices you can get to
connect your pipework to a car foot pump to do a pressure test,

... snipped

That sounds like a b***dy good idea. I need to do some plumbing which
will then be "built-in" before I can test it with water - it would be
good to be able to do an air pressure test. Does anyone have any more
info? (although I guess it's an easy enough thing to lash together)
Presumably the necessary volume of air would be a problem.


How about this?
http://www.screwfix.com/app/sfd/cat/...10179&ts=29302

They do a cheaper one, but it doesn't have a schrader valve - so you'd have
to invent your own way of pressurising the pipework.
http://www.screwfix.com/app/sfd/cat/...82412%26p%3Dx4
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Set Square wrote:
In an earlier contribution to this discussion,
Dave wrote:


Markus Splenius wrote:
... snipped

I'm far from being an expert, but there are devices you can get to
connect your pipework to a car foot pump to do a pressure test,

... snipped

That sounds like a b***dy good idea. I need to do some plumbing which
will then be "built-in" before I can test it with water - it would be
good to be able to do an air pressure test. Does anyone have any more
info? (although I guess it's an easy enough thing to lash together)
Presumably the necessary volume of air would be a problem.



How about this?
http://www.screwfix.com/app/sfd/cat/...10179&ts=29302

They do a cheaper one, but it doesn't have a schrader valve - so you'd have
to invent your own way of pressurising the pipework.
http://www.screwfix.com/app/sfd/cat/...82412%26p%3Dx4

Thanks! I'd never thought of air testing pipework before this thread ...
this illustrates one of life's big difficulties: you don't know what you
don't know! (and, of course, the value of this newsgroup!)

--
Dave S
(The return email address is a dummy)

On Fri, 21 Jan 2005 17:39:22 +0000 (UTC), "John"
strung together this:

I once found a leak under the floor of an office block in Leeds by putting a
big dose of Fernox MB1 into the system and waiting till one of the denizens
reported an unusual smell.

I once found a leak under the floor of an office block in Leeds by
lifting a floor tile to run some data cables through and found an 8'
square lake!
--

SJW
Please reply to group or use 'usenet' in email subject

I'm a bit stuck at this point. It occurs to me it would be quite
helpful to know if there is a water leak or not. If one propped up the
float in the header tank and watched twice daily, it should be possible
to see what happens to the water level there, whether it drops, rises
or stays. But I'm not gonig to suggest that, as if the boiler ends up
heating air filled pipework it could be bye bye boiler.
Maybe a better idea exists.


NT

On 21 Jan 2005 12:28:55 -0800, wrote:

I'm a bit stuck at this point. It occurs to me it would be quite
helpful to know if there is a water leak or not. If one propped up the
float in the header tank and watched twice daily, it should be possible
to see what happens to the water level there, whether it drops, rises
or stays. But I'm not gonig to suggest that, as if the boiler ends up
heating air filled pipework it could be bye bye boiler.
Maybe a better idea exists.


NT


I did something similar, closed the valve on the mains inlet. The
level does seem to be dropping, so it does look like a leak. Was
wondering if anyone has used any of the leak sealers e.g. Fernox, must
be worth a go.

"Lurch" wrote in message
...
On Fri, 21 Jan 2005 17:39:22 +0000 (UTC), "John"
strung together this:

I once found a leak under the floor of an office block in Leeds by putting
a
big dose of Fernox MB1 into the system and waiting till one of the
denizens
reported an unusual smell.

I once found a leak under the floor of an office block in Leeds by
lifting a floor tile to run some data cables through and found an 8'
square lake!

Did it smell of Fernox? g

On Fri, 21 Jan 2005 21:52:01 +0000 (UTC), "John"
strung together this:

I once found a leak under the floor of an office block in Leeds by
lifting a floor tile to run some data cables through and found an 8'
square lake!

Did it smell of Fernox? g

Smelt more of not been tested! It was a brand new office block with
busbar power tracks screwed on the floor. (Could mention the office on
a very large development and the contractors, but I'd probably better
not!)
--

SJW
Please reply to group or use 'usenet' in email subject