Hi, I have problem with my heating system. The system has a single
pump system with 2 zone valves one for hot water cylinder and one for
heating.

The problem is when the valve for hot water is open which feeds the
cylinder, there is bubbling noise coming from the overflow pipe to the
small expansion tank. When the heating only is open its seems fine.
Only when the hot water is on there is bubbling noise. The pump is set
to speed III, if i turn it to II the bubbling noise is not there, but
the rads don't heat up.

My cylinder, and both zone valves are in the loft. The cold water
feeder from the small tank in connected to the return from the
cylinder.

Does anyone know what the problem might be.

Michael

In article
,
michael wrote:
The problem is when the valve for hot water is open which feeds the
cylinder, there is bubbling noise coming from the overflow pipe to the
small expansion tank.

Have you looked at it? If water (and or 'steam') is coming out of the pipe
it's called pumping over. Which is not 'a good thing'�

When the heating only is open its seems fine.
Only when the hot water is on there is bubbling noise. The pump is set
to speed III, if i turn it to II the bubbling noise is not there, but
the rads don't heat up.

Have the rads been balanced? If all the lockshields are wide open the pump
might well need to run flat out to circulate the water. Balancing them
should allow it to be turned down. Details on balancing in the FAQ.

--
*The beatings will continue until morale improves *

Dave Plowman London SW
To e-mail, change noise into sound.

On 14 Oct, 09:50, "Dave Plowman (News)" wrote:
In article
,
* *michael wrote:

The problem is when the valve for hot water is open which feeds the
cylinder, there is bubbling noise coming from the overflow pipe to the
small expansion tank.

Have you looked at it? If water (and or 'steam') is coming out of the pipe
it's called pumping over. Which is not 'a good thing' *

When the heating only is open its seems fine.
Only when the hot water is on there is bubbling noise. The pump is set
to speed III, if i turn it to II the bubbling noise is not there, but
the rads don't heat up.

Have the rads been balanced? If all the lockshields are wide open the pump
might well need to run flat out to circulate the water. Balancing them
should allow it to be turned down. Details on balancing in the FAQ.

--
*The beatings will continue until morale improves *

* * Dave Plowman * * * * * * * * London SW
* * * * * * * * * To e-mail, change noise into sound.

When the heating is on (only) and not the hot water its fine all rads
get hot, its only when the hot water is on either with or without
heating does bubbles appear and air goes in the system from the
overflow vent.

"michael" wrote

Hi, I have problem with my heating system. The system has a single
pump system with 2 zone valves one for hot water cylinder and one for
heating.

The problem is when the valve for hot water is open which feeds the
cylinder, there is bubbling noise coming from the overflow pipe to the
small expansion tank. When the heating only is open its seems fine.
Only when the hot water is on there is bubbling noise. The pump is set
to speed III, if i turn it to II the bubbling noise is not there, but
the rads don't heat up.

My cylinder, and both zone valves are in the loft. The cold water
feeder from the small tank in connected to the return from the
cylinder.

Does anyone know what the problem might be.


Hi Michael
Have you bled and re-bled all the rads and any other bleed points on the
system?
My system tends to be noisier at start up when hot water only is being
heated. Once all the air is eradicated (say after a drain down), the system
quietens down.
If your zone valves are high in the system and close to the vent and/or fill
points (this is pretty standard with pump and valves in airing cupboard),
then they are more prone to magnetite deposits. If the system is older -
say 10 years plus - then this may be an issue. The deposits reduce the bore
of the pipe and valves which results in higher water velocities locally
(hence perhaps bubbling). The only way to check will be to drain down,
partially, and remove/inspect valve and pipe work.

As others have said, if you are seeing water pumping over the vent into the
header tank, then this needs to be resolved. Test the system in all modes
to make sure this is not occurring.

Not sure why you would need speed 3 to get rads to work - is it a micro or
small bore system?


Phil

On Wed, 14 Oct 2009 06:21:54 -0700 (PDT), michael wrote:

When the heating is on (only) and not the hot water its fine all rads
get hot, its only when the hot water is on either with or without
heating does bubbles appear and air goes in the system from the
overflow vent.

Sounds as if the pump is working to hard and drawing air down the
vent pipe when in HW only. The physical layout of pipes/pumps and
vent/feed connections are important. I think you'd find the
recomendations on the Grunfoss site.

You say that if you use II that doesn't happen but the rads don't get
hot. Is that with HW and CH demand or just CH? I'd look at the CH
circuit as Mr Plowman suggests and make sure the system is balanced
and doesn't have any air locks or rads full of air.

--
Cheers
Dave.

On 14 Oct, 14:00, "TheScullster" wrote:
"michael" wrote



Hi, I have problem with my heating system. The system has a single
pump system with 2 zone valves one for hot water cylinder and one for
heating.

The problem is when the valve for hot water is open which feeds the
cylinder, there isbubblingnoise coming from the overflow pipe to the
small expansion tank. When the heating only is open its seems fine.
Only when the hot water is on there isbubblingnoise. The pump is set
to speed III, if i turn it to II thebubblingnoise is not there, but
the rads don't heat up.

My cylinder, and both zone valves are in the loft. The cold water
feeder from the small tank in connected to the return from the
cylinder.

Does anyone know what the problem might be.

Hi Michael
Have you bled and re-bled all the rads and any other bleed points on the
system?
My system tends to be noisier at start up when hot water only is being
heated. *Once all the air is eradicated (say after a drain down), the system
quietens down.
If your zone valves are high in the system and close to the vent and/or fill
points (this is pretty standard with pump and valves in airing cupboard),
then they are more prone to magnetite deposits. *If the system is older -
say 10 years plus - then this may be an issue. *The deposits reduce the bore
of the pipe and valves which results in higher water velocities locally
(hence perhapsbubbling). *The only way to check will be to drain down,
partially, and remove/inspect valve and pipe work.

As others have said, if you are seeing water pumping over the vent into the
header tank, then this needs to be resolved. *Test the system in all modes
to make sure this is not occurring.

Not sure why you would need speed 3 to get rads to work - is it a micro or
small bore system?

Phil

Hi Phil,
Its a 15mm system. The plumber re-located the vent after the pump but
before the heater zone value. It now goes down by 12" then U turns up
to the expansion tank. (Before, the vent was before the pump on the
same level as the inlet to the hot water cylinder) Now the bubbling
noise is gone. Now when heating and hot water is one all in fine. But
when the hot water only is on there seems to be a problem of air in
the system, as the boiler turns off after a short while and the temp
goes up to 75c which I have seen when there is air in the pipes.

I should say the hot water cylinder, the two zone valves, and the pump
are all located in the loft. The boiler is in the kitchen.

Michael.

On Nov 3, 7:49*pm, michael wrote:
On 14 Oct, 14:00, "TheScullster" wrote:



"michael" wrote

Hi, I have problem with my heating system. The system has a single
pump system with 2 zone valves one for hot water cylinder and one for
heating.

The problem is when the valve for hot water is open which feeds the
cylinder, there isbubblingnoise coming from the overflow pipe to the
small expansion tank. When the heating only is open its seems fine.
Only when the hot water is on there isbubblingnoise. The pump is set
to speed III, if i turn it to II thebubblingnoise is not there, but
the rads don't heat up.

My cylinder, and both zone valves are in the loft. The cold water
feeder from the small tank in connected to the return from the
cylinder.

Does anyone know what the problem might be.

Hi Michael
Have you bled and re-bled all the rads and any other bleed points on the
system?
My system tends to be noisier at start up when hot water only is being
heated. *Once all the air is eradicated (say after a drain down), the system
quietens down.
If your zone valves are high in the system and close to the vent and/or fill
points (this is pretty standard with pump and valves in airing cupboard),
then they are more prone to magnetite deposits. *If the system is older -
say 10 years plus - then this may be an issue. *The deposits reduce the bore
of the pipe and valves which results in higher water velocities locally
(hence perhapsbubbling). *The only way to check will be to drain down,
partially, and remove/inspect valve and pipe work.

As others have said, if you are seeing water pumping over the vent into the
header tank, then this needs to be resolved. *Test the system in all modes
to make sure this is not occurring.

Not sure why you would need speed 3 to get rads to work - is it a micro or
small bore system?

Phil

Hi Phil,
Its a 15mm system. The plumber re-located the vent after the pump but
before the heater zone value. It now goes down by 12" then U turns up
to the expansion tank. (Before, the vent was before the pump on the
same level as the inlet to the hot water cylinder) Now the bubbling
noise is gone. Now when heating and hot water is one all in fine. But
when the hot water only is on there seems to be a problem of air in
the system, as the boiler turns off after a short while and the temp
goes up to 75c which I have seen when there is air in the pipes.

I should say the hot water cylinder, the two zone valves, and the pump
are all located in the loft. The boiler is in the kitchen.

Michael.

sounds to me like air in the radiator circuit. Turn pump speed down
first, as you'll never resolve it without doing that, then bleed all
rads. I'm no expert on this stuff though.


NT