Hi all,

My CH upgrade is going well.
Germans and Italians have some pretty fancy sealed system thingys.
My pump is on its last legs, so will have to replace it soon.
Has anyone any opinions (silly me, of course you have) about alpha pumps?
I'm not quite sure how they work.
What are their advantages over standard pumps?



Francis

On Tue, 21 Sep 2004 11:48:21 +0100, "FrancisJK"
wrote:

Hi all,

My CH upgrade is going well.
Germans and Italians have some pretty fancy sealed system thingys.
My pump is on its last legs, so will have to replace it soon.
Has anyone any opinions (silly me, of course you have) about alpha pumps?
I'm not quite sure how they work.
What are their advantages over standard pumps?


Yes I do.

Basically, they back off the power as flow restriction increases, so
for example, if you have TRVs, the pump doesn't run its nuts off and
become noisy. It has a peak pressure point at just below 0.5 m^3/hr.
Above this it has a typical head/flow curve. Below it the power is
reduced as restriction increases.

I found that mine therefore runs a lot quieter than erstwhile models.

There are a few other features such as a deblocking function.

http://www.grundfos-www.com/alpha/frames_html.htm

Nice product and well worth having.



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Tue, 21 Sep 2004 11:48:21 +0100, "FrancisJK"
wrote:

Hi all,

My CH upgrade is going well.
Germans and Italians have some pretty fancy sealed system thingys.
My pump is on its last legs, so will have to replace it soon.
Has anyone any opinions (silly me, of course you have) about alpha pumps?
I'm not quite sure how they work.
What are their advantages over standard pumps?


Yes I do.

Basically, they back off the power as flow restriction increases, so
for example, if you have TRVs, the pump doesn't run its nuts off and
become noisy. It has a peak pressure point at just below 0.5 m^3/hr.
Above this it has a typical head/flow curve. Below it the power is
reduced as restriction increases.

I found that mine therefore runs a lot quieter than erstwhile models.

There are a few other features such as a deblocking function.

http://www.grundfos-www.com/alpha/frames_html.htm

Nice product and well worth having.



.andy

To email, substitute .nospam with .gl


WOOOOOOOOOO HOOOOOOOOOOOOOOOOOOOOOOOOOOOO

Thanks Andy. That installation team can install my pump right away!


Francis

"FrancisJK" wrote in message
...

"Andy Hall" wrote in message
...
On Tue, 21 Sep 2004 11:48:21 +0100, "FrancisJK"
wrote:

Hi all,

My CH upgrade is going well.
Germans and Italians have some pretty fancy sealed system thingys.
My pump is on its last legs, so will have to replace it soon.
Has anyone any opinions (silly me, of course you have) about alpha
pumps?
I'm not quite sure how they work.
What are their advantages over standard pumps?


Yes I do.

Basically, they back off the power as flow restriction increases, so
for example, if you have TRVs, the pump doesn't run its nuts off and
become noisy. It has a peak pressure point at just below 0.5 m^3/hr.
Above this it has a typical head/flow curve. Below it the power is
reduced as restriction increases.

I found that mine therefore runs a lot quieter than erstwhile models.

There are a few other features such as a deblocking function.

http://www.grundfos-www.com/alpha/frames_html.htm

Nice product and well worth having.



.andy

To email, substitute .nospam with .gl


WOOOOOOOOOO HOOOOOOOOOOOOOOOOOOOOOOOOOOOO

I assume you are woo-hooing the 4 birds in cat suits. Those birds go to
trendy bars and pull out their Alphas while ordering a Martini.

FrancisJK wrote:

Thanks Andy. That installation team can install my pump right away!

Or better still, pump your install!

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Yes I do.

Basically, they back off the power as flow restriction increases, so
for example, if you have TRVs, the pump doesn't run its nuts off and
become noisy. It has a peak pressure point at just below 0.5 m^3/hr.
Above this it has a typical head/flow curve. Below it the power is
reduced as restriction increases.

I found that mine therefore runs a lot quieter than erstwhile models.

There are a few other features such as a deblocking function.

http://www.grundfos-www.com/alpha/frames_html.htm

Nice product and well worth having.


Would it work as well on a microbore system ?

My installation consists of 22mm (may be 28) pipe which does a circuit
under the 1st floor. From this, each rad has a tee down to microbore
(probably 10mm). Only a short distance for the upstairs rads and down
behind the plasterboard walls for the downstairs rads.

I guess there is more resistance in this setup than an 'ordinary'
setup.

Alan

"Alan Campbell" wrote in message
om...

Yes I do.

Basically, they back off the power as flow restriction increases, so
for example, if you have TRVs, the pump doesn't run its nuts off and
become noisy. It has a peak pressure point at just below 0.5 m^3/hr.
Above this it has a typical head/flow curve. Below it the power is
reduced as restriction increases.

I found that mine therefore runs a lot quieter than erstwhile models.

There are a few other features such as a deblocking function.

http://www.grundfos-www.com/alpha/frames_html.htm

Nice product and well worth having.


Would it work as well on a microbore system ?

My installation consists of 22mm (may be 28) pipe which does a circuit
under the 1st floor. From this, each rad has a tee down to microbore
(probably 10mm). Only a short distance for the upstairs rads and down
behind the plasterboard walls for the downstairs rads.

I guess there is more resistance in this setup than an 'ordinary'
setup.

It will work just as well on Microbore.

"Alan Campbell" wrote in message
om...

Yes I do.

Basically, they back off the power as flow restriction increases, so
for example, if you have TRVs, the pump doesn't run its nuts off and
become noisy. It has a peak pressure point at just below 0.5 m^3/hr.
Above this it has a typical head/flow curve. Below it the power is
reduced as restriction increases.

I found that mine therefore runs a lot quieter than erstwhile models.

There are a few other features such as a deblocking function.

http://www.grundfos-www.com/alpha/frames_html.htm

Nice product and well worth having.


Would it work as well on a microbore system ?

My installation consists of 22mm (may be 28) pipe which does a circuit
under the 1st floor. From this, each rad has a tee down to microbore
(probably 10mm). Only a short distance for the upstairs rads and down
behind the plasterboard walls for the downstairs rads.

My installation, heating loop, conists of a two-floor teeoff
with, on each floor, the distribution pipes stepping down
to each rad. Every rad is fed by 10mm pipes but the distribution
pipe steps down at each stage; -

=22==22-10-15==15==15-10-10===10==
| |
|
Rad Rad Rad
| |
|
=22==22-10-15==15==15-10-10===10==

each floor has a minimum of copper although it uses
several sizes of piping. The design/installation was at
a time when copper prices were going through the roof
-and Belgian paratroopers were dropping onto the
coppermines in Zaire (or was it the Congo.?)


I guess there is more resistance in this setup than an 'ordinary'
setup.

Alan

--

Brian

On 22 Sep 2004 05:08:11 -0700, (Alan
Campbell) wrote:


Yes I do.

Basically, they back off the power as flow restriction increases, so
for example, if you have TRVs, the pump doesn't run its nuts off and
become noisy. It has a peak pressure point at just below 0.5 m^3/hr.
Above this it has a typical head/flow curve. Below it the power is
reduced as restriction increases.

I found that mine therefore runs a lot quieter than erstwhile models.

There are a few other features such as a deblocking function.

http://www.grundfos-www.com/alpha/frames_html.htm

Nice product and well worth having.


Would it work as well on a microbore system ?

My installation consists of 22mm (may be 28) pipe which does a circuit
under the 1st floor. From this, each rad has a tee down to microbore
(probably 10mm). Only a short distance for the upstairs rads and down
behind the plasterboard walls for the downstairs rads.

I guess there is more resistance in this setup than an 'ordinary'
setup.

Alan

Generally the pressure drop across a microbore system is a bit more
than on 15mm systems but not hugely so if the system was designed
properly.

Tube resistance is higher, but as long as the flow carrying capacity
was taken into account, it should be OK. You can do a sanity check
on this if you go to the Copper Development Association website.
There is a downloadable paper on pipe sizing for domestic systems.
If you know the lengths of pipes reasonably you can calculate the
maximum flow rate and heat transfer possible. The basis is no more
than 1.5m/sec to avoid noise from the pipework. Since flow rate and
heat transfer are linearly related you can determine the heat transfer
allowable.

Rule of thumb, this equates to about 1500W over typical house
distances of a few metres for 8mm and 2500W for 10mm.

You can then check your radiators. Measure them and look at the
number of panels and fins. Then look at a/the manufacturer's web site
at the datasheet and you can get the nominal power output. If you
have a conventional non condensing boiler, multiply the radiator
manufacturer number by 0.9 to get the true output. You only need to
do this for the largest radiators.

As long as you are reasonably close to being within the limits, then
all should be well.

Some installers through laziness or incompetence or just hoping, may
have overloaded the pipes. This may not be a problem. All that
will happen is that you may hear noise from that part of the system or
the radiator runs below capacity.

I have an 8mm system, and when it had an Alpha pump on it, it worked
well. Some of the radiators were 20% over the nominal limit for the
pipework. I should add that the reason for moving it was because I
now have a boiler with integrated pump and that is controlled linearly
by the boiler controller according to heat load, so nothing upon which
the Alpha could improve.
The Alpha is still doing good service in a separate circuit for my
workshop






..andy

To email, substitute .nospam with .gl

"FrancisJK" wrote in message
...
Hi all,

My CH upgrade is going well.
Germans and Italians have some pretty fancy sealed system thingys.
My pump is on its last legs, so will have to replace it soon.
Has anyone any opinions (silly me, of course you have) about alpha pumps?

Yes - quite simply the Alpha pump is the biggest advance in plumbing in
years and should be mandated to be put into every home thereby allowing us
to close umpteen power stations.

Okay bit over the top but once you've tried one you won't want to go back to
anything else.

"FrancisJK" wrote in message
...

Has anyone any opinions (silly me, of course you have) about alpha pumps?

With an alpha, as TRVs close the flow falls but the head does not rise
as in normal pumps. With a normal pump you need a bypass. So normal
pump+bypass gives constant-ish flow rate and return temperature rises
as TRVs close. Alpha gives reducing flow and a lower return
temperature.

Hence Alpha's are a good idea if you have a condensing boiler since
those are more efficient with lower return temperature. But normal +
bypass is probably better for a standard boiler since they do NOT want
a lower return temperature due to the risk of condensing causing
boiler corrosion.


--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
, or ).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:

http://www.fullcircuit.com or http://www.fullcircuit.co.uk

NEW - Desktop ToDo/Reminder program (free)

"Malcolm Reeves" wrote in message
...

"FrancisJK" wrote in message
...

Has anyone any opinions (silly me, of course you have) about alpha
pumps?

With an alpha, as TRVs close the flow falls but the head does not rise
as in normal pumps. With a normal pump you need a bypass. So normal
pump+bypass gives constant-ish flow rate and return temperature rises
as TRVs close. Alpha gives reducing flow and a lower return
temperature.

Hence Alpha's are a good idea if you have a condensing boiler since
those are more efficient with lower return temperature. But normal +
bypass is probably better for a standard boiler since they do NOT want
a lower return temperature due to the risk of condensing causing
boiler corrosion.

People use these having TVRs on all rads. Boilers require a minimum flow
through the rads, using TRVs on all will reduce this flow. A flow switch
that cuts out the burner is required when the flow gets below the boiler
makers stated flow.

Using a by-pass on a "modern" condensing boiler defeats much of its purpose.
Older condensing boilers had the same design specs as regular boilers: the
Ideal Minimiser stated 80C flow and 11C delta T on flow and return. The
makers did say that you can stretch it to 15C.

On Wed, 22 Sep 2004 09:57:06 +0100, Malcolm Reeves
wrote:


"FrancisJK" wrote in message
...

Has anyone any opinions (silly me, of course you have) about alpha pumps?

With an alpha, as TRVs close the flow falls but the head does not rise
as in normal pumps.

Not exactly.

Between a certain range of flow/pressure, the Alpha behaves
conventionally. When the flow falls below a certain point, that is
detected and the power is reduced to reduce the head.


With a normal pump you need a bypass. So normal
pump+bypass gives constant-ish flow rate and return temperature rises
as TRVs close. Alpha gives reducing flow and a lower return
temperature.

Only close to the point of total closure.


Hence Alpha's are a good idea if you have a condensing boiler since
those are more efficient with lower return temperature. But normal +
bypass is probably better for a standard boiler since they do NOT want
a lower return temperature due to the risk of condensing causing
boiler corrosion.

it's suitable for a normal boiler as well, since if the bypass opens,
the flow increases anyway.




..andy

To email, substitute .nospam with .gl

In an earlier contribution to this discussion,
Andy Hall wrote:


it's suitable for a normal boiler as well, since if the bypass opens,
the flow increases anyway.


The thing that worries me about this discussion, though, is that if the
Alpha has reduced its power/speed/head because the flow has reduced, there
may not be enough head to open the by-pass. There may not then be enough
flow through the boiler to remove the residual heat after it stops firing.
How do you ensure that this doesn't happen?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On Wed, 22 Sep 2004 13:09:32 +0100, "Set Square"
wrote:

In an earlier contribution to this discussion,
Andy Hall wrote:


it's suitable for a normal boiler as well, since if the bypass opens,
the flow increases anyway.


The thing that worries me about this discussion, though, is that if the
Alpha has reduced its power/speed/head because the flow has reduced, there
may not be enough head to open the by-pass. There may not then be enough
flow through the boiler to remove the residual heat after it stops firing.
How do you ensure that this doesn't happen?


By setting the bypass appropriately.

You can also adjust the pump.


..andy

To email, substitute .nospam with .gl

On Wed, 22 Sep 2004 13:09:32 +0100, "Set Square"
wrote:

In an earlier contribution to this discussion,
Andy Hall wrote:


it's suitable for a normal boiler as well, since if the bypass opens,
the flow increases anyway.


The thing that worries me about this discussion, though, is that if the
Alpha has reduced its power/speed/head because the flow has reduced, there
may not be enough head to open the by-pass.

True, or if the bypass opens before the alpha "effect" kicks in what
is the point of an alpha? Basically they both do similar things so
its debatable which you need.

There may not then be enough
flow through the boiler to remove the residual heat after it stops firing.
How do you ensure that this doesn't happen?

How does a bypass remove residual heat? For that the pump has to run
so you need pump overrun not bypass. However, you may need a bypass
and pump overrun to cover the situation of all rads with TRVs (which
you shouldn't have) and needing to get rid of some heat (to the pipe
work presumably).



--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
, or ).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:

http://www.fullcircuit.com or http://www.fullcircuit.co.uk

NEW - Desktop ToDo/Reminder program (free)

"Andy Hall" wrote in message
...
On Wed, 22 Sep 2004 09:57:06 +0100, Malcolm Reeves
wrote:


"FrancisJK" wrote in message
...

Has anyone any opinions (silly me, of course you have) about alpha
pumps?

With an alpha, as TRVs close the flow falls but the head does not rise
as in normal pumps.

Not exactly.

Between a certain range of flow/pressure, the Alpha behaves
conventionally. When the flow falls below a certain point, that is
detected and the power is reduced to reduce the head.


With a normal pump you need a bypass. So normal
pump+bypass gives constant-ish flow rate and return temperature rises
as TRVs close. Alpha gives reducing flow and a lower return
temperature.

Only close to the point of total closure.


Hence Alpha's are a good idea if you have a condensing boiler since
those are more efficient with lower return temperature. But normal +
bypass is probably better for a standard boiler since they do NOT want
a lower return temperature due to the risk of condensing causing
boiler corrosion.

it's suitable for a normal boiler as well, since if the bypass opens,
the flow increases anyway.




.andy

To email, substitute .nospam with .gl

Andy,

I'm now puzzled.

Is it a choice between

Standard pump AND automativ by-pass

against

Alpha Pump AND no by-pass


Francis

On Wed, 22 Sep 2004 13:38:42 +0100, "FrancisJK"
wrote:


"Andy Hall" wrote in message
.. .
On Wed, 22 Sep 2004 09:57:06 +0100, Malcolm Reeves
wrote:


"FrancisJK" wrote in message
...

Has anyone any opinions (silly me, of course you have) about alpha
pumps?

With an alpha, as TRVs close the flow falls but the head does not rise
as in normal pumps.

Not exactly.

Between a certain range of flow/pressure, the Alpha behaves
conventionally. When the flow falls below a certain point, that is
detected and the power is reduced to reduce the head.


With a normal pump you need a bypass. So normal
pump+bypass gives constant-ish flow rate and return temperature rises
as TRVs close. Alpha gives reducing flow and a lower return
temperature.

Only close to the point of total closure.


Hence Alpha's are a good idea if you have a condensing boiler since
those are more efficient with lower return temperature. But normal +
bypass is probably better for a standard boiler since they do NOT want
a lower return temperature due to the risk of condensing causing
boiler corrosion.

it's suitable for a normal boiler as well, since if the bypass opens,
the flow increases anyway.




.andy

To email, substitute .nospam with .gl

Andy,

I'm now puzzled.

Is it a choice between

Standard pump AND automativ by-pass

against

Alpha Pump AND no by-pass


Francis

Not as far as I am concerned.

You can use an Alpha pump either way.

The point comes back to the earlier one of what do you want the boiler
to do when the flow becomes low as the result of the TRVs beginning to
close.

If it;s a conventional boiler, you want it to be locked off by the
room thermostat when the flow becomes so low that the boiler begins to
short cycle as a result of the high boiler output vs. low demand..
That will happen if if the flow rate is low because the TRVs have
reduced it or if the return temperature is high because there is a
substantial amount of bypass. Therefore you have the room
thermostat in a room without TRV to put that additional control in
place and stop the boiler shortly after the TRVs have reduced the
load.

With a condensing boiler, you still want to detect this case, but
because the boiler will have modulated down adjustment will be easier.

It's useful to have a bypass anyway, to cover the case where the
boiler has been in full burn and the heat demand is suddenly satisfied
- this is the pump over-run case. Some boilers have very low water
content and if they have an integral pump can live with an internal
bypass as well. If you have an external pump, then an external
bypass is normally used anyway - in the form of a lockshield valve
across flow and return. Using an automatic bypass instead is a
better idea just for that since you are not shunting the flow back to
the return until either the CH has reached low demand or turned off
altogether.


..andy

To email, substitute .nospam with .gl

"FrancisJK" wrote in message
...


I'm now puzzled.

Is it a choice between

Standard pump AND automativ by-pass

against

Alpha Pump AND no by-pass


No. I have a conventional boiler, Alpha pump and an automatic bypass. Plus
4 zones valves run from room thermostats and only a couple of TRVs. This
gives lots of degrees of freedom in setting up the system to operate
efficiently - or in getting it wrong if you don't set it up well.

"Malcolm Reeves" wrote in message
...

"FrancisJK" wrote in message
...

Has anyone any opinions (silly me, of course you have) about alpha
pumps?

With an alpha, as TRVs close the flow falls but the head does not rise
as in normal pumps. With a normal pump you need a bypass. So normal
pump+bypass gives constant-ish flow rate and return temperature rises
as TRVs close. Alpha gives reducing flow and a lower return
temperature.

Hence Alpha's are a good idea if you have a condensing boiler since
those are more efficient with lower return temperature. But normal +
bypass is probably better for a standard boiler since they do NOT want
a lower return temperature due to the risk of condensing causing
boiler corrosion.


--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
, or ).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and
Power
electronics. More details plus freeware, Win95/98 DUN and Pspice tips,
see:

http://www.fullcircuit.com or http://www.fullcircuit.co.uk

NEW - Desktop ToDo/Reminder program (free)


Hi Malcom,

Great site. I have not heard BESPOKE since that TV show "Never mind the
quality, feel the width". I'll have a look in detail later.

We have a back boiler unit at the moment, which is coming to the end of its
life.

I have an automatic by-pass valve in the circuit, but I'm not sure how to
set it. Any guidance on this appreciated.


Francis

On Wed, 22 Sep 2004 12:53:55 +0100, "FrancisJK"
wrote:

I have an automatic by-pass valve in the circuit, but I'm not sure how to
set it. Any guidance on this appreciated.

The one I have just says set it 20% above the on state head so what
I'd do is first balance the system with all TRVs open and bypass set
to off. Then reduce bypass until there was some flow (pipe gets hot)
then turn bypass up a bit so there was no flow.

--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
, or ).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:

http://www.fullcircuit.com or http://www.fullcircuit.co.uk

NEW - Desktop ToDo/Reminder program (free)