In order to solve my noisy trv problem I have just replaced my pump
with a Grundfos Alpha. During fitting it became obvious the the
original layout (about 35yrs old) had the pump on the boiler return. As
the new pump/trvs are still producing noise, I wonder if the G/Alpha is
not capable of sensing the required info for it to slow down (anybody
know what they sense?) Another 'iff area' is I had to fit with the
inlet/outlet in the horizontal plane (as was the original) and the
motor shaft horizontal. Grundfos instructions require the 'motor shaft'
to be horizontal, but show a pic with the in/out vertical! Anyone got
any thoughts on this one please?

On 22 Jan 2006 12:32:51 -0800, "Peter Walton"
wrote:

In order to solve my noisy trv problem I have just replaced my pump
with a Grundfos Alpha. During fitting it became obvious the the
original layout (about 35yrs old) had the pump on the boiler return. As
the new pump/trvs are still producing noise, I wonder if the G/Alpha is
not capable of sensing the required info for it to slow down (anybody
know what they sense?)

AIUI, it's rotor speed (relates to flow) and motor load (relates to
head).

Another 'iff area' is I had to fit with the
inlet/outlet in the horizontal plane (as was the original) and the
motor shaft horizontal. Grundfos instructions require the 'motor shaft'
to be horizontal, but show a pic with the in/out vertical! Anyone got
any thoughts on this one please?


Regarding the TRVs... have you checked that they are installed the
right way round? Tyoically if this is wrong, you will get a vibrating
or chattering sound.

Is it possible that you have most or all of the lockshield valves
turned down too far? This could also be because of one or two
radiators being too large for the pipework feeding them and the others
having to be turned down to compensate. Try rebalancing the system
according to the group FAQ. The noise with restricted flow sounds
like a rushing of water.

As far as the pump mounting is concerned, you can have the pipe runs
vertical or horizontal. WHat you can't do is have the shaft vertical.


--

..andy

Andy Hall wrote:

As far as the pump mounting is concerned, you can have the pipe runs
vertical or horizontal.

Although it's considered undesirable to pump downwards as it can make it
more difficult to get all the air out of the system when filling.

--
Andy

On Sun, 22 Jan 2006 21:49:54 +0000, Andy Wade
wrote:

Andy Hall wrote:

As far as the pump mounting is concerned, you can have the pipe runs
vertical or horizontal.

Although it's considered undesirable to pump downwards as it can make it
more difficult to get all the air out of the system when filling.


The pump isn't running then, though....


--

..andy

In an earlier contribution to this discussion,
Peter Walton wrote:

In order to solve my noisy trv problem I have just replaced my pump
with a Grundfos Alpha. During fitting it became obvious the the
original layout (about 35yrs old) had the pump on the boiler return.
As the new pump/trvs are still producing noise, I wonder if the
G/Alpha is not capable of sensing the required info for it to slow
down (anybody know what they sense?) Another 'iff area' is I had to
fit with the inlet/outlet in the horizontal plane (as was the
original) and the motor shaft horizontal. Grundfos instructions
require the 'motor shaft' to be horizontal, but show a pic with the
in/out vertical! Anyone got any thoughts on this one please?

It is sensing 'resistance to flow' and is attempting (within limits) to
maintain a constant head (pressure) regardless of the amount of flow.
Whether it's in the flow or return pipe shouldn't make any difference to
that.

It is distinctly possible that your TRVs are uni-directional, and that the
flow is gowing through them in the *wrong* direction. When water is flowing
through a radiator, you can tell which is the flow pipe and which is the
return by feeling them - the flow pipe is hotter. The TRVs will probably
have an arrow on them to indicate the required flow direction. Check whether
they are the right way round.

As far as I know, the only stipulation is that the motor shaft must be
horizontal. You can rotate the pump body around that horizontal axis to make
the pipes point in any direction you like (within the same vertical plane).

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Andy Hall wrote:

On Sun, 22 Jan 2006 21:49:54 +0000, Andy Wade
wrote:

Although it's considered undesirable to pump downwards as it can make it
more difficult to get all the air out of the system when filling.

The pump isn't running then, though....

No, but (IME[1]) you can never completely fill a system in one go. In
fact it usually takes about a month's running to get _all_ the air out,
during which time a downward pumping pump is not an advantage.

[1] Which excludes sealed systems.

--
Andy

On Tue, 24 Jan 2006 00:37:04 +0000, Andy Wade
wrote:

Andy Hall wrote:

On Sun, 22 Jan 2006 21:49:54 +0000, Andy Wade
wrote:

Although it's considered undesirable to pump downwards as it can make it
more difficult to get all the air out of the system when filling.

The pump isn't running then, though....

No, but (IME[1]) you can never completely fill a system in one go. In
fact it usually takes about a month's running to get _all_ the air out,
during which time a downward pumping pump is not an advantage.

[1] Which excludes sealed systems.


OK, I see what you're saying.


--

..andy

On Tue, 24 Jan 2006 00:37:04 +0000, Andy Wade wrote:

Andy Hall wrote:

On Sun, 22 Jan 2006 21:49:54 +0000, Andy Wade
wrote:

Although it's considered undesirable to pump downwards as it can make it
more difficult to get all the air out of the system when filling.

The pump isn't running then, though....

No, but (IME[1]) you can never completely fill a system in one go. In
fact it usually takes about a month's running to get _all_ the air out,
during which time a downward pumping pump is not an advantage.

[1] Which excludes sealed systems.

It's much the same for sealed systems. Although you can get 90% of the air
out as you fill and most of the rest a few minutes after starting the pump
it still take a long time for the _all_ the small air bubbles to settle
out.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

Thanks Guys... The pump is now working fine, seems it was me not
understanding how it operates, and being impatient! I wired an ampmeter
into the pump circuit and did some 'long term' monitoring under a range
of conditions, it seems it takes the pump (or my system) between 10 -
15 mins to respond but when it does the current swings nicely to the
appropriate setting. Still have some noise but I suspect this is air
and not the original TRV screaming, and it seems to me getting less
active. Happy with the setup now as its ticking over at an average of
0.15amp (say 35watts) the original pump was rated at 80! so we can mark
another tick for the 'save the planet' project.