I think I know the answer(!) but there just might be something out there
which I'm not aware of.

I'm trying to adjust the automatic by-pass valve on my heating system so
that it opens when the pump is running with both zone valves closed (i.e. in
pump over-run conditions) but stays shut when water is circulating normally.

Problem is that it's very difficult to tell when it's open. It's a Pegler
USV 16/22-PE which has a knob to turn to set the opening pressure, but no
external indication of what the innards are doing. It's in the airing
cupboard, close to the pump and zone valves, and a long way from the boiler.
Listening to its outlet pipe with a stethoscope or feeling how hot the pipe
gets are both inconclusive because sound and heat are transmitted from pipe
to pipe even when there's no flow.

What I really need is something akin to a clamp-on ammeter which will
measure the flow in the by-pass circuit without having to be plumbed in.
Anyone know if anything like this exists - at consumer-level prices, of
course!?
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored..
Messages sent to it may not be read for several weeks. PLEASE REPLY TO
NEWSGROUP!

Roger Mills wrote:
I think I know the answer(!) but there just might be something out there
which I'm not aware of.

I'm trying to adjust the automatic by-pass valve on my heating system so
that it opens when the pump is running with both zone valves closed (i.e. in
pump over-run conditions) but stays shut when water is circulating normally.

Problem is that it's very difficult to tell when it's open. It's a Pegler
USV 16/22-PE which has a knob to turn to set the opening pressure, but no
external indication of what the innards are doing. It's in the airing
cupboard, close to the pump and zone valves, and a long way from the boiler.
Listening to its outlet pipe with a stethoscope or feeling how hot the pipe
gets are both inconclusive because sound and heat are transmitted from pipe
to pipe even when there's no flow.

What I really need is something akin to a clamp-on ammeter which will
measure the flow in the by-pass circuit without having to be plumbed in.
Anyone know if anything like this exists - at consumer-level prices, of
course!?
Could you do something with a differential thermometer.
If there is no flow through any of the radiators then the temperature
difference between flow and return will be around zero.

Bob

In message , Bob Minchin
writes
Roger Mills wrote:
I think I know the answer(!) but there just might be something out
there which I'm not aware of.
I'm trying to adjust the automatic by-pass valve on my heating
system so that it opens when the pump is running with both zone
valves closed (i.e. in pump over-run conditions) but stays shut when
water is circulating normally.
Problem is that it's very difficult to tell when it's open. It's a
Pegler USV 16/22-PE which has a knob to turn to set the opening
pressure, but no external indication of what the innards are doing.
It's in the airing cupboard, close to the pump and zone valves, and a
long way from the boiler. Listening to its outlet pipe with a
stethoscope or feeling how hot the pipe gets are both inconclusive
because sound and heat are transmitted from pipe to pipe even when
there's no flow.
What I really need is something akin to a clamp-on ammeter which
will measure the flow in the by-pass circuit without having to be
plumbed in. Anyone know if anything like this exists - at
consumer-level prices, of course!?
Could you do something with a differential thermometer.
If there is no flow through any of the radiators then the temperature
difference between flow and return will be around zero.


Vaillant have tried this - it doesn't work very well


--
geoff

Roger Mills wrote:

What I really need is something akin to a clamp-on ammeter which will
measure the flow in the by-pass circuit without having to be plumbed in.
Anyone know if anything like this exists - at consumer-level prices, of
course!?

I know its possible because I used to have a water filter that monitored
the cartridge use with a flow detector of some sort. It ran from a
couple of AAs, and had a pair of small metal "pads" that poked into a
recess in the plastic that had the water flowing past the other side. I
often wondered how it worked, but never investigated much further. I
presume it just timed how long water was flowing, rather than actually
metering consumption as such.

A few ideas spring to mind:

Adding a flow switch in series with the valve would obviously tell you.

Perhaps some sort of system that relies on displacement of a magnet by
the flow. which you could then detect with a a read switch or a hall
effect transistor.

Maybe a pressure sensor on the feed side could detect the drop in static
pressure when the valve opens.

Ideally it would be best if you could do it without assistance of
anything introduced into the flow... but I am not sure what distinct
property of flowing water you could detect. There may be an electrical
characteristic that changes - I wonder if you could make a section of
plastic pipe part of a capacitor and sense a change in value with water
flowing?



--
Cheers,

John.

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

In an earlier contribution to this discussion,
John Rumm wrote:

Roger Mills wrote:

What I really need is something akin to a clamp-on ammeter which will
measure the flow in the by-pass circuit without having to be plumbed
in. Anyone know if anything like this exists - at consumer-level
prices, of course!?

I know its possible because I used to have a water filter that
monitored the cartridge use with a flow detector of some sort. It ran
from a couple of AAs, and had a pair of small metal "pads" that poked
into a recess in the plastic that had the water flowing past the
other side. I often wondered how it worked, but never investigated
much further. I presume it just timed how long water was flowing,
rather than actually metering consumption as such.

A few ideas spring to mind:

Adding a flow switch in series with the valve would obviously tell
you.
Perhaps some sort of system that relies on displacement of a magnet by
the flow. which you could then detect with a a read switch or a hall
effect transistor.

Maybe a pressure sensor on the feed side could detect the drop in
static pressure when the valve opens.

Ideally it would be best if you could do it without assistance of
anything introduced into the flow... but I am not sure what distinct
property of flowing water you could detect. There may be an electrical
characteristic that changes - I wonder if you could make a section of
plastic pipe part of a capacitor and sense a change in value with
water flowing?


Many thanks for your comments. I was really hoping for something which I
could fit round the existing pipework without disturbing the plumbing - but
I guessed that that would be too much to hope for!

If I do have to break into the pipework, a flow-switch would indicate *some*
flow, but wouldn't give any idea of how much the valve was open. Another
option, I suppose, is to fit a water meter such as http://tinyurl.com/6ldly9
[1] in the pipe. That has a twirly bit in the middle which rotates at a rate
proportional to the flow, and the counter would actually give litres per
minute if used in conjunction with a stop-watch.

[1] I already have one of these - with the plastic hose adaptors replaced
with 3/4"MI to 15mm comp fittings - in my mains water supply to help me
decide whether I would be better off having a water meter fitted by Severn
Trent. The one I have is only suitable for cold water, but a hot water (up
to 90 degC) version is also available.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

No idea what you have looked at, but saw tyhis:

http://www.maxiflo.co.kr/English/Technology/flowmetertypes.htm

Describes quite a range of metering options!

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

"Roger Mills" wrote in message
...
I think I know the answer(!) but there just might be something out there
which I'm not aware of.

I'm trying to adjust the automatic by-pass valve on my heating system so
that it opens when the pump is running with both zone valves closed (i.e.
in pump over-run conditions) but stays shut when water is circulating
normally.

Problem is that it's very difficult to tell when it's open. It's a Pegler
USV 16/22-PE which has a knob to turn to set the opening pressure, but no
external indication of what the innards are doing. It's in the airing
cupboard, close to the pump and zone valves, and a long way from the
boiler. Listening to its outlet pipe with a stethoscope or feeling how hot
the pipe gets are both inconclusive because sound and heat are transmitted
from pipe to pipe even when there's no flow.

What I really need is something akin to a clamp-on ammeter which will
measure the flow in the by-pass circuit without having to be plumbed in.
Anyone know if anything like this exists - at consumer-level prices, of
course!?

Best eliminate the by-pass valve. Insert a plate heat exchanger, about £90
and the size of a book. Have the boiler's flow and return pump into it
right at the boiler. On the other side of the plate have the flow and return
to the DHW and CH. Put a Smart pump on this side.

Then there is always full flow through the boiler and no sludge enters the
boiler, as it is isolated, protecting it. The Smart pump winds down when
the TRVs are all closed, and you can have TRVs on all rads. Simple,
foolproof, better temp control in all rooms, total protection of the boiler
in full flow through it and no sludge enters.

In message , Rod
writes
No idea what you have looked at, but saw tyhis:

http://www.maxiflo.co.kr/English/Technology/flowmetertypes.htm

Describes quite a range of metering options!

Ah! Thermal mass.

I have long thought that the simple Thermistor could be used for non
contact sensing applications.

Mind you, BG seem very anxious to change my electronic gas meter:-)

regards






--
Tim Lamb

Roger Mills wrote:

Many thanks for your comments. I was really hoping for something which I
could fit round the existing pipework without disturbing the plumbing - but
I guessed that that would be too much to hope for!

Indeed it would be the nice option.

If I do have to break into the pipework, a flow-switch would indicate *some*
flow, but wouldn't give any idea of how much the valve was open. Another
option, I suppose, is to fit a water meter such as http://tinyurl.com/6ldly9
[1] in the pipe. That has a twirly bit in the middle which rotates at a rate
proportional to the flow, and the counter would actually give litres per
minute if used in conjunction with a stop-watch.

Any system that introduces a passive impeller into the flow should be
able to give you flow and rate indication.

Perhaps if you do make changes to the pipework you could go for an
alternative arrangement where you introduce a diversion valve ahead of
the existing zone valves such that in its non energised state the flow
is directed through the bypass (which would not even need the bypass
valve in this case). You could then "wire or" each of the relay
outputs from the existing two port valves such that they energise the
new valve. Hence when any call for heat is made, the existing valves
will obtain position, and then call for the flow to be diverted through
them. When demand ceases and they all close, the diversion valve returns
flow to the bypass. (you might get a very brief interruption to the flow
in that form - however if you derive the permanent supply to the aux
contacts on the zone vales from their activation inputs, the diversion
valve would be de-energised when demand ceases and hence should be back
in bypass mode before the zones all close).



--
Cheers,

John.

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

In an earlier contribution to this discussion,
John Rumm wrote:


Perhaps if you do make changes to the pipework you could go for an
alternative arrangement where you introduce a diversion valve ahead of
the existing zone valves such that in its non energised state the flow
is directed through the bypass (which would not even need the bypass
valve in this case). You could then "wire or" each of the relay
outputs from the existing two port valves such that they energise the
new valve. Hence when any call for heat is made, the existing valves
will obtain position, and then call for the flow to be diverted
through them. When demand ceases and they all close, the diversion
valve returns flow to the bypass. (you might get a very brief
interruption to the flow in that form - however if you derive the
permanent supply to the aux contacts on the zone vales from their
activation inputs, the diversion valve would be de-energised when
demand ceases and hence should be back in bypass mode before the
zones all close).

That's a very interesting thought! I had wondered about using another zone
valve in the by-pass leg, which opened when the others were closed - plus
some suitable relay logic to drive it. Using a valve which is open in the
de-engerised state, as you suggest, would probably make life easier -
although I may still need a relay unless I simply power it from the OR'd
auxilliary contact outputs of the zone valves, which would result in a
slight delay before my new valve opens. I may *still* need a by-pass valve
in parallel with this new zone valve to provide enough flow through the
boiler when all but one TRV are closed - but it could be set tighter than at
present since it should never have to take *all* the flow.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:
In an earlier contribution to this discussion,
John Rumm wrote:

Roger Mills wrote:

What I really need is something akin to a clamp-on ammeter which will
measure the flow in the by-pass circuit without having to be plumbed
in. Anyone know if anything like this exists - at consumer-level
prices, of course!?

Ther is SOMETHING I remember seeing about..it relies on some combination
of electrical potential and magnets to make a sort of half a wind
electric motor.

If the fluid is relatively conductive. Which CH or tap water is.

The principle being IIRC that te fluid can be considered to be a series
of little 'wries/ that tarvel across a magnetic field, and induce a
potential on either side of the tube at right angles to the magnetic
field. Probaly a few millivolts at best, even with serous neodymium
magnets, but measurable.


So something like a plastic pipe with a horseshoe magnet round it and a
couple of electrodes inside it to measure potential into some sensitive
meter. You could test it with a DVM and pins stuck through a garden
hose..and any magnets that will go round it.

Roger Mills wrote:
In an earlier contribution to this discussion,
John Rumm wrote:

Perhaps if you do make changes to the pipework you could go for an
alternative arrangement where you introduce a diversion valve ahead of
the existing zone valves such that in its non energised state the flow
is directed through the bypass (which would not even need the bypass
valve in this case). You could then "wire or" each of the relay
outputs from the existing two port valves such that they energise the
new valve. Hence when any call for heat is made, the existing valves
will obtain position, and then call for the flow to be diverted
through them. When demand ceases and they all close, the diversion
valve returns flow to the bypass. (you might get a very brief
interruption to the flow in that form - however if you derive the
permanent supply to the aux contacts on the zone vales from their
activation inputs, the diversion valve would be de-energised when
demand ceases and hence should be back in bypass mode before the
zones all close).

That's a very interesting thought! I had wondered about using another zone
valve in the by-pass leg, which opened when the others were closed - plus
some suitable relay logic to drive it. Using a valve which is open in the
de-engerised state, as you suggest, would probably make life easier -
although I may still need a relay unless I simply power it from the OR'd
auxilliary contact outputs of the zone valves, which would result in a
slight delay before my new valve opens. I may *still* need a by-pass valve

Yup, but that is ok, since we are only talking about a second or two,
and you still have free flow through the bypass before it does divert.

in parallel with this new zone valve to provide enough flow through the
boiler when all but one TRV are closed - but it could be set tighter than at
present since it should never have to take *all* the flow.

Firstly have you not got a bypass rad (e.g. in the room with a zone
stat)? Secondly would not your variable flow pump not take care of this
situation anyway?


--
Cheers,

John.

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

In an earlier contribution to this discussion,
John Rumm wrote:

Roger Mills wrote:
In an earlier contribution to this discussion,

That's a very interesting thought! I had wondered about using
another zone valve in the by-pass leg, which opened when the others
were closed - plus some suitable relay logic to drive it. Using a
valve which is open in the de-energised state, as you suggest, would
probably make life easier - although I may still need a relay unless
I simply power it from the OR'd auxilliary contact outputs of the
zone valves, which would result in a slight delay before my new
valve opens.

Yup, but that is ok, since we are only talking about a second or two,
and you still have free flow through the bypass before it does divert.

Yes, it probably wouldn't long enough to matter. The contacts wouldn't
open - and allow the by-pass motorised valve to move to the open position
until the zone valve(s) have *already* started to close but, as you say, any
time for which the zone valves and by-pass valve are all closed should be
very short.


I may *still* need a by-pass valve in parallel with this new zone valve
to provide enough flow through
the boiler when all but one TRV are closed - but it could be set
tighter than at present since it should never have to take *all* the
flow.

Firstly have you not got a bypass rad (e.g. in the room with a zone
stat)? Secondly would not your variable flow pump not take care of
this situation anyway?

Yes, I *have* got a rad which is always open - but only just! It's in the
hallway (where the room stat is) and is really a bit larger than is needed -
so it's throttled back a hell of a lot on its lockshield - otherwise that
space gets too hot and turns off the whole system too early.

The question is whether - with all but one rads shut - that one throttled
rad would pass enough flow to keep the boiler happy. It would actually pass
less still if the variable speed pump unloaded itself.

[At the moment, my Alpha+ pump is on a constant speed setting - which is the
only way I can get it to open the automatic by-pass valve when the zone
valves are shut without opening it all the time - see my other thread on
"Automatic by-pass valves and variable speed pumps"].
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
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PLEASE REPLY TO NEWSGROUP!