Hi,

My central heating system seems to be making a number of funny noises...

- The pump sometimes speeds up and slows down - this is accompanied with
what I could call a vibration noise. Very low pitched and not very loud.
More like its coming from the pipes rather than the pump.

- At irregular intervals a loud-ish gurgling sound comes from the radiator
in the master bedroom. This is accompanied by a sound I would compare to
water running into the radiator. Almost as if I had taken the (imaginary)
cap of the top of it and poured water into it. A water on metal sound - like
its filling up but its full of water which a quick unscrew of the bleed
valve confirms.

- If you put your hand on the pipe work in the airing cupboard (when not)
hot, around every second you can feel something almost like someone is
tapping on the pipe - a slight movement. Perhaps "knocking" would be a good
description.

.... also ...

- The master bedroom radiator requires bleeding on around a two weekly
interval.

The system is (I'll describe as not sure on the exact description), Gloworm
Ultimate boiler, a [something] Gold pump, has hot water tank and a small
header tank in the loft. Is this an "open vented" system? The hot water tank
has a small tank on the top which I believe provides the head for the
system.

Thinking about it, is it fare to say that the only mechanical part of the
system is the pump so It might be worth replacing this?

Thanks in advance,

CM.

Charles Middleton wrote:

- The pump sometimes speeds up and slows down - this is accompanied with
what I could call a vibration noise. Very low pitched and not very loud.
More like its coming from the pipes rather than the pump.

- At irregular intervals a loud-ish gurgling sound comes from the radiator
in the master bedroom. This is accompanied by a sound I would compare to
water running into the radiator. Almost as if I had taken the (imaginary)
cap of the top of it and poured water into it. A water on metal sound - like
its filling up but its full of water which a quick unscrew of the bleed
valve confirms.

- If you put your hand on the pipe work in the airing cupboard (when not)
hot, around every second you can feel something almost like someone is
tapping on the pipe - a slight movement. Perhaps "knocking" would be a good
description.

Sounds very much like you have air in the system.


- The master bedroom radiator requires bleeding on around a two weekly
interval.

And that your are sucking in air somewhere at quite a high rate. This
air then collects at the first convenient location - your radiator.


The system is (I'll describe as not sure on the exact description), Gloworm
Ultimate boiler, a [something] Gold pump, has hot water tank and a small
header tank in the loft.

Ok.


Is this an "open vented" system?

Yes.


The hot water tank
has a small tank on the top which I believe provides the head for the
system.

Thinking about it, is it fare to say that the only mechanical part of the
system is the pump so It might be worth replacing this?

No, the pump is not the problem.

Air is being sucked in. There are many possible places where it could
enter the system, but the most likely place is through the vent - the
pipe which hangs over the edge of your smaller loft tank.

If this is the case, then you may be able to cure it by reducing the
pump speed (there's a 3 way switch on the pump). But this will upset the
balance of your system, and may lead to inadequate performance.

The best solution is to figure out where your vent pipe connects in the
circuit, and relocate it to a better place. This is a design flaw in the
system - the vent pipe is connected too near the pump inlet, so water
gets sucked in though it.


--
Grunff

On Mon, 25 Oct 2004 13:51:11 +0000 (UTC), "Charles Middleton"
wrote:

Hi,

My central heating system seems to be making a number of funny noises...

- The pump sometimes speeds up and slows down - this is accompanied with
what I could call a vibration noise. Very low pitched and not very loud.
More like its coming from the pipes rather than the pump.

It could be the pump on its way out or perhaps air getting into the
system.


- At irregular intervals a loud-ish gurgling sound comes from the radiator
in the master bedroom. This is accompanied by a sound I would compare to
water running into the radiator. Almost as if I had taken the (imaginary)
cap of the top of it and poured water into it. A water on metal sound - like
its filling up but its full of water which a quick unscrew of the bleed
valve confirms.

There probably is *some* air, it's just that it takes two weeks to
gather a noticable amount.


- If you put your hand on the pipe work in the airing cupboard (when not)
hot, around every second you can feel something almost like someone is
tapping on the pipe - a slight movement. Perhaps "knocking" would be a good
description.

With the pump running? Otherwise pipes in another part of the system
which are getting hot or cool and are expanding or contracting.


... also ...

- The master bedroom radiator requires bleeding on around a two weekly
interval.

That's a fair bit and should be investigated.


The system is (I'll describe as not sure on the exact description), Gloworm
Ultimate boiler, a [something] Gold pump, has hot water tank and a small
header tank in the loft. Is this an "open vented" system? The hot water tank
has a small tank on the top which I believe provides the head for the
system.

Could you elucidate a bit more.

Do you mean that there is a small tank in the roof and then separately
and somewhere else there is a HW cylinder with its own small tank
separate to the first?

In any case it's an open vented system, but if you only had a single
header tank on the HW cylinder doing everything then it probably means
that you have a Primatic cylinder and the way to proceed is rather
different.





Thinking about it, is it fare to say that the only mechanical part of the
system is the pump so It might be worth replacing this?

It could be, but there may be other issues. Can you comment on the
system first. Also important if you have a small separate tank in the
roof is whether there is enough water in it. Also the relative
positions of the vent pipe leading to and over this tank and the
feed/expansion pipe going from the bottom. It's quite important to
know where these join the main system, how far apart etc.





Thanks in advance,

CM.


..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...

Hi Andy, thanks for the reply. My comments are below ...

- If you put your hand on the pipe work in the airing cupboard (when not)
hot, around every second you can feel something almost like someone is
tapping on the pipe - a slight movement. Perhaps "knocking" would be a
good
description.

With the pump running? Otherwise pipes in another part of the system
which are getting hot or cool and are expanding or contracting.

This is with the pump running.

The system is (I'll describe as not sure on the exact description),
Gloworm
Ultimate boiler, a [something] Gold pump, has hot water tank and a small
header tank in the loft. Is this an "open vented" system? The hot water
tank
has a small tank on the top which I believe provides the head for the
system.

Could you elucidate a bit more.

Do you mean that there is a small tank in the roof and then separately
and somewhere else there is a HW cylinder with its own small tank
separate to the first?

That is what I meant. There is a small tank in the roof and the HW cylinder
has a small tank on the top of it.

Thinking about it, is it fare to say that the only mechanical part of the
system is the pump so It might be worth replacing this?

It could be, but there may be other issues. Can you comment on the
system first. Also important if you have a small separate tank in the
roof is whether there is enough water in it. Also the relative
positions of the vent pipe leading to and over this tank and the
feed/expansion pipe going from the bottom. It's quite important to
know where these join the main system, how far apart etc.

Hopefully comments above have clarified the type of system. I'll have to get
into the loft and have a look at hte latter points. I'm away all this week
so will need to have a look at teh weekend. To clarify ...

- The feed/expansion pipe: I presume this is what will "top up" the system
and also keep it pressurised?

- The vent pipe - what is this used for?

CM.

On Mon, 25 Oct 2004 16:14:30 +0000 (UTC), "Charles Middleton"
wrote:


"Andy Hall" wrote in message
.. .

Hi Andy, thanks for the reply. My comments are below ...

- If you put your hand on the pipe work in the airing cupboard (when not)
hot, around every second you can feel something almost like someone is
tapping on the pipe - a slight movement. Perhaps "knocking" would be a
good
description.

With the pump running? Otherwise pipes in another part of the system
which are getting hot or cool and are expanding or contracting.

This is with the pump running.

It could be that the pump bearing is knackered, but I wouldn't shell
out for a new pump just yet.



The system is (I'll describe as not sure on the exact description),
Gloworm
Ultimate boiler, a [something] Gold pump, has hot water tank and a small
header tank in the loft. Is this an "open vented" system? The hot water
tank
has a small tank on the top which I believe provides the head for the
system.

Could you elucidate a bit more.

Do you mean that there is a small tank in the roof and then separately
and somewhere else there is a HW cylinder with its own small tank
separate to the first?

That is what I meant. There is a small tank in the roof and the HW cylinder
has a small tank on the top of it.

That's good. In that case it's a conventional open vent system and
you can do things to the primary (heating) water without impact on the
domestic hot water.





Thinking about it, is it fare to say that the only mechanical part of the
system is the pump so It might be worth replacing this?

It could be, but there may be other issues. Can you comment on the
system first. Also important if you have a small separate tank in the
roof is whether there is enough water in it. Also the relative
positions of the vent pipe leading to and over this tank and the
feed/expansion pipe going from the bottom. It's quite important to
know where these join the main system, how far apart etc.

Hopefully comments above have clarified the type of system. I'll have to get
into the loft and have a look at hte latter points. I'm away all this week
so will need to have a look at teh weekend. To clarify ...

- The feed/expansion pipe: I presume this is what will "top up" the system
and also keep it pressurised?

Yes, but it's not a pressurised system in the sense that you might
have read about pressurised systems. They are completely closed in.
The only static pressure that you have is by virtue of the height of
the small tank in the roof.




- The vent pipe - what is this used for?

To let air out of the system and in the event of a boiler malfunction
such that it boils, steam. Some people mistakenly call it the
expansion pipe - it isn't.

The pipe near the bottom is called the feed/expansion pipe because it
allows the system to be filled and as the water is heated, it can
expand back up into the tank.

In a correctly designed system, these two pipes should join the main
circuit within about 150mm of one another and definitely not on
opposing sides of the pump. Sometimes they join at a little chamber
called an air separator which is used to make convenient connections
and get air out of the system.

If the connections are not to the right places, or are too far apart,
then there is a pressure differential and either air is sucked down
the vent pipe or water pumped over. You may have the first of these,
but it's not so obvious to see as the pump over case. Often it
happens when motorised valves are changing or when the the pump
starts.

Another possibility is that there is too little water in the small
tank and when cold some air enters the system down the feed pipe.
Often this is because the ball valve is stuck and the cure is simple.
When the water is cold you need say 50mm depth above the feed pipe at
the bottom - no more because you need to allow for a rise in the water
level with expansion.

It's possible that corrosion is happening in the system. That would
be if there is no inhibitor and if the escaping "air" from when you
vent is actually hydrogen and burns with a small blue flame.

The source of the gas/air in the system does need to be investigated
and fixed. If you are into doing some plumbing, information on how
to fix the vent arrangement if this is what it seems to be can be
provided here - helpful if you can put some photos on a web site.

I wouldn't spend money on a new pump at this point, but it could be
worth turning it down a notch as suggested and see if the venting and
noise issues reduce. If they do, then you have your culprit.


..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Mon, 25 Oct 2004 16:14:30 +0000 (UTC), "Charles Middleton"
wrote:


snip

Didn't have time to take any pics over the weekend. Ill do it next weekend
and create a suitably titled thread with a link to the pictures.

Thanks all for the help. Is it safe to test if the gas in the radiator is
nitrogen by setting alight to it? What's the worst that can happen?

CM.

In an earlier contribution to this discussion,
Charles Middleton wrote:

"Andy Hall" wrote in message
...
On Mon, 25 Oct 2004 16:14:30 +0000 (UTC), "Charles Middleton"
wrote:


snip

Didn't have time to take any pics over the weekend. Ill do it next
weekend and create a suitably titled thread with a link to the
pictures.

Thanks all for the help. Is it safe to test if the gas in the
radiator is nitrogen by setting alight to it? What's the worst that
can happen?

CM.

If it's nitrogen, nothing!

In the more likely case that it's hydrogen, it will burn with a blue flame -
but is unlikely to set fire to your house. Have a wet cloth ready in case
you need to smother it.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On Mon, 1 Nov 2004 10:16:31 +0000 (UTC), "Charles Middleton"
wrote:


"Andy Hall" wrote in message
.. .
On Mon, 25 Oct 2004 16:14:30 +0000 (UTC), "Charles Middleton"
wrote:


snip

Didn't have time to take any pics over the weekend. Ill do it next weekend
and create a suitably titled thread with a link to the pictures.

Thanks all for the help. Is it safe to test if the gas in the radiator is
nitrogen by setting alight to it? What's the worst that can happen?

CM.


I guess you mean hydrogen. Charles.

You can test with a flame. Obviously move anything flammable likle
curtains out of the way, and have a damp cloth handy. Then just open
vent very slightly and apply small flame. If you get a blue flame
it's hydrogen....



--

..andy

To email, substitute .nospam with .gl