I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting
on my pump by requiring the water to go up 3m, then across the width of
the room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

On Sun, 06 Nov 2011 22:11:52 +0000
puffernutter wrote:

I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central
heating system.

In essence I needed the pipes to the radiator to come from the
opposite side of the room and the only solution was to go "up and
over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am
putting on my pump by requiring the water to go up 3m, then across
the width of the room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit
at a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

Not being a heating engineer, I would think that the net increase in
length of pipework was part of the problem.
--
Davey.

On Sun, 6 Nov 2011 22:48:36 +0000, Davey wrote:

Not being a heating engineer, I would think that the net increase in
length of pipework was part of the problem.

Well it won't help but I wouldn't expect it to stop the radiator
working, at least not if all the pipes are full of water.

Has all the air been bled from the top of the inverted "U" feeding
this radiator? There needs to be an bleed point at the highest point.
Bleeding the rad doesn't clear the air from the higher pipe work.

--
Cheers
Dave.

On 06/11/2011 22:11, puffernutter wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting on
my pump by requiring the water to go up 3m, then across the width of the
room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

I expect it is possible there is an air lock in this 'n' shaped pipe run.

I don't think the up/down is an issue, as you could setup a siphon with
pipe as high as you like, as long as the outlet is below the inlet, it
will work.
The pipe resistance may well be an issue though.

I would try turning off all the radiators in the house, except this one,
open the valves to this one fully, and then get the pump running, this
may push any trapped air out.

Do you have a sealed system, or an open vented one?


--
Toby...
Remove pants to reply

On 06/11/2011 23:27, Toby wrote:
On 06/11/2011 22:11, puffernutter wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting on
my pump by requiring the water to go up 3m, then across the width of the
room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

I expect it is possible there is an air lock in this 'n' shaped pipe run.

I don't think the up/down is an issue, as you could setup a siphon with
pipe as high as you like, as long as the outlet is below the inlet, it
will work.
The pipe resistance may well be an issue though.

I would try turning off all the radiators in the house, except this one,
open the valves to this one fully, and then get the pump running, this
may push any trapped air out.

Do you have a sealed system, or an open vented one?


All very good thoughts and advice. Thank you.

I will investigate and let you know what I find.

Cheers

Peter

--

On 06/11/2011 22:11, puffernutter wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting on
my pump by requiring the water to go up 3m, then across the width of the
room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Probably not. Its either an airlock in one of the pipes, or you need to
rebalance the rads to allow for the extra flow resistance.

For an airlock, you will either need to find a way to bleed air at the
top of the loop, or possibly just shut down all the other rads, and let
the pump force flow through that problem one. That should shift the air
(where will depend a little on the layout of the system and if its
vented or sealed).

--
Cheers,

John.

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

puffernutter wrote:

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting
on my pump by requiring the water to go up 3m, then across the width of
the room then down 3m. With the return doing the same.

It's hardly unusual for houses to have pipes that go up (from downstairs to
upstairs) and back down again; I would have thought that pumps would be able
to cope with that ok.

--
Jeremy C B Nicoll - my opinions are my own.

Email sent to my from-address will be deleted. Instead, please reply
to replacing "aaa" by "284".

On Nov 6, 10:11*pm, puffernutter
wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. *I wonder is this is because the additional load I am putting
on my pump by requiring the water to go up 3m, then across the width of
the room then down 3m. *With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

I agree with others that the an airlock at the top of the n is a
possibility. In a similar situation I know, with pipes going up 'n
over a doorway at the highest point in the system, the Corgi (or
whatever they're called this week) had to install what looks like an
automatic relief valve to clobber the resultant perpetual airlock.

The other usual question following a summer shutdown is: has the TRV
stuck? Remove the head and make sure that the pin moves up and down.
You'll probably need a flat bit of metal to press against it. It
should spring up and down a millimetre or so. If it doesn't, use
pliers to work it up and down a few times, or a bit of "percussive
maintenance" (tap it with a hammer) to free it. A new twist on this
that I've recently discovered is that some TRVs (Landis & Gyr anyway)
have a bias adjustment that you can use to set them, presumably so
that 3 (say) is the optimum setting throughout the house. Somehow or
other, some of these adjusters were keeping their rads off even with
the head removed. It's a little clock-like thing with the "hand" slot
you push round.

Chris

On Nov 6, 10:11*pm, puffernutter
wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. *I wonder is this is because the additional load I am putting
on my pump by requiring the water to go up 3m, then across the width of
the room then down 3m. *With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

As a minimum the system will have to be rebalanced.
There may also be air trapped in the pipework. This can be fixed with
an automatic air vent or a bleed valve (similar to the ones on
radiators)
The pump is unlikely to be able to move trapped air.

The pump may be adjustable speed and you can increase it by means of a
switch on it.

"Toby" wrote in message
...

I don't think the up/down is an issue, as you could setup a siphon with
pipe as high as you like, as long as the outlet is below the inlet, it
will work.

That's not actually true.. you can't exceed ~10m, at that point the water
will break into a vacuum in the pipe and no water can ever pass using a
siphon.
Its the reason why wells have to have the pump at the bottom, you just can't
"suck" water up any higher.

In article , Toby wrote:
I don't think the up/down is an issue, as you could setup a siphon with
pipe as high as you like, as long as the outlet is below the inlet, it
will work.

Not strictly true, but the OP's 3m is under that limit (about 34ft, 10.3m).

In article ,
Alan Braggins wrote:
In article , Toby wrote:
I don't think the up/down is an issue, as you could setup a siphon with
pipe as high as you like, as long as the outlet is below the inlet, it
will work.

Not strictly true, but the OP's 3m is under that limit (about 34ft,
10.3m).

Unless, of course, the pipes are filled with something other than water. If
it were mercury, the allowable height would only be about 30 inches. ;-)

--
From KT24

Using a RISC OS computer running v5.16

On Mon, 07 Nov 2011 09:09:36 +0000, dennis@home wrote:
Its the reason why wells have to have the pump at the bottom, you just
can't "suck" water up any higher.

Agreed on the sucking aspect, but just to point out that a well doesn't
have to have the pump at the bottom - mine's approx 86 feet deep with a
surface-mounted jet pump (I'm not sure if there's a practical limit at
which point a jet pump is no good and a submersible pump *has* to be
used, however).

cheers

Jules

On Mon, 07 Nov 2011 11:34:30 +0000, charles wrote:
Unless, of course, the pipes are filled with something other than water.
If it were mercury, the allowable height would only be about 30 inches.
;-)

:-) How much mercury would you need to fill an average CH system?

The suggestion of one pipe being airlocked is a good one. Try bleeding with
alternate valves closed.

In message , Toby
writes
On 06/11/2011 22:11, puffernutter wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting on
my pump by requiring the water to go up 3m, then across the width of the
room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

I expect it is possible there is an air lock in this 'n' shaped pipe run.

I don't think the up/down is an issue, as you could setup a siphon with
pipe as high as you like, as long as the outlet is below the inlet, it
will work.
The pipe resistance may well be an issue though.

I would try turning off all the radiators in the house, except this
one, open the valves to this one fully, and then get the pump running,
this may push any trapped air out.

Do you have a sealed system, or an open vented one?


In CH systems pumps effectively don't push, they suck. If you run the
pump with a bleed valve open you will simply suck in more air.
--
hugh

Jules Richardson wrote:
On Mon, 07 Nov 2011 09:09:36 +0000, dennis@home wrote:
Its the reason why wells have to have the pump at the bottom, you just
can't "suck" water up any higher.

Agreed on the sucking aspect, but just to point out that a well doesn't
have to have the pump at the bottom - mine's approx 86 feet deep with a
surface-mounted jet pump (I'm not sure if there's a practical limit at
which point a jet pump is no good and a submersible pump *has* to be
used, however).

cheers

Jules


32 ft is as far as you can suck water up IIRC.

if your well is 86ft the pump is NOT at the top.

Unless its putting PRESSURE on the reservoir below.


So I guess the pump mechanicals may be a ground level, but the actual
jet part is way down where the sun don't shine.

hugh wrote:
In message , Toby
writes
On 06/11/2011 22:11, puffernutter wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting on
my pump by requiring the water to go up 3m, then across the width of the
room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

I expect it is possible there is an air lock in this 'n' shaped pipe run.

I don't think the up/down is an issue, as you could setup a siphon
with pipe as high as you like, as long as the outlet is below the
inlet, it will work.
The pipe resistance may well be an issue though.

I would try turning off all the radiators in the house, except this
one, open the valves to this one fully, and then get the pump running,
this may push any trapped air out.

Do you have a sealed system, or an open vented one?


In CH systems pumps effectively don't push, they suck. If you run the
pump with a bleed valve open you will simply suck in more air.

wrong, as usual. They essentially do both.

The correct way to get out trapped air is to run the pump flat out with
plenty of pressure in the loop, and shut down everything except the cold
rad. WITH LUCK this will blast the air to a lower point where it can be
bled.

In my case a high loop through the attic was the issue..eventually it
blew the air down into a bleedable rad.

In article , Jules Richardson wrote:
On Mon, 07 Nov 2011 09:09:36 +0000, dennis@home wrote:
Its the reason why wells have to have the pump at the bottom, you just
can't "suck" water up any higher.

Agreed on the sucking aspect, but just to point out that a well doesn't
have to have the pump at the bottom - mine's approx 86 feet deep with a
surface-mounted jet pump (I'm not sure if there's a practical limit at
which point a jet pump is no good and a submersible pump *has* to be
used, however).

http://www.popularmechanics.com/home...umbing/1275136
reckons "several hundred feet". But part of the pump mechanism is down the
well even if the main pump is on the surface, you can't suck it up from
above that far.

On Mon, 07 Nov 2011 15:36:01 +0000, The Natural Philosopher wrote:
if your well is 86ft the pump is NOT at the top.

Yes, it is. It's an injector-type setup; on the surface is a large
centrifugal pump which diverts a portion of the pumped water back via a
return line down to the jet at the bottom of the well - e.g. see under
"well pumps":

http://en.wikipedia.org/wiki/Injector

I suppose you could term the jet to be a "pump" too, but to me it's just
an injector and the actual "pumping" is all done top-side.

I don't think they're as common these days (submersible pumps are the
norm), but I like them because just about all of the critical stuff is at
surface level so can be worked on easily.

Looking at the manual for ours, 150 feet seems to be the depth limit, but
I don't know if that's a technological limit or specific to the pump /
jet that we have - that and ours turned 40 this year, so maybe things
have moved on since then :-)

cheers

Jules

Jules Richardson wrote:
On Mon, 07 Nov 2011 15:36:01 +0000, The Natural Philosopher wrote:
if your well is 86ft the pump is NOT at the top.

Yes, it is. It's an injector-type setup; on the surface is a large
centrifugal pump which diverts a portion of the pumped water back via a
return line down to the jet at the bottom of the well - e.g. see under
"well pumps":

http://en.wikipedia.org/wiki/Injector

I suppose you could term the jet to be a "pump" too, but to me it's just
an injector and the actual "pumping" is all done top-side.


well exactly.

I don't think they're as common these days (submersible pumps are the
norm), but I like them because just about all of the critical stuff is at
surface level so can be worked on easily.

Looking at the manual for ours, 150 feet seems to be the depth limit, but
I don't know if that's a technological limit or specific to the pump /
jet that we have - that and ours turned 40 this year, so maybe things
have moved on since then :-)


as long as you have pressure at depth, you can in pronciple pump to any
height.

The 'working' part of a jet pump is the jet.

That's at the well bottom.


cheers

Jules

On 06/11/11 22:11, puffernutter wrote:
I know, if it ain't broke.....

Over the summer, as part of a longer term task to fit a shower in the
downstairs cloakroom, I made some minor changes to the central heating
system.

In essence I needed the pipes to the radiator to come from the opposite
side of the room and the only solution was to go "up and over".

I now find that the radiator, whilst full of water when bled, doesn't
get hot. I wonder is this is because the additional load I am putting on
my pump by requiring the water to go up 3m, then across the width of the
room then down 3m. With the return doing the same.

When the pipework stayed on the skirting (as it was originally) the
radiator worked fine.

If I remove the bleed screw, then the water will come through, albeit at
a much lower pressure than I might have expected.

So, is the simple solution to fit a more powerful circulating pump?

Cheers

Peter

Just to be sure ... the valves at both ends of the radiator are open,
aren't they?

On 07/11/2011 15:08, Jules Richardson wrote:
On Mon, 07 Nov 2011 11:34:30 +0000, charles wrote:
Unless, of course, the pipes are filled with something other than water.
If it were mercury, the allowable height would only be about 30 inches.
;-)

:-) How much mercury would you need to fill an average CH system?

It would be interesting to see the rad fall off the walls as well!


--
Cheers,

John.

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

On 07/11/2011 15:29, hugh wrote:

In CH systems pumps effectively don't push, they suck.

Not sure its really possible to do one without the other.


--
Cheers,

John.

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

On Nov 8, 5:07*pm, John Rumm wrote:
On 07/11/2011 15:29, hugh wrote:

In CH systems pumps effectively don't push, they suck.

Not sure its really possible to do one without the other.

Another type of blow job really then.

On Mon, 07 Nov 2011 15:36:01 +0000, The Natural Philosopher
wrote:

So I guess the pump mechanicals may be a ground level, but the actual
jet part is way down where the sun don't shine.

Exactly. I had one here, with a footvalve that does the jet-pumping
operation. My borehole is 60' deep afaik - although it might be less
now, as it's not been used for a decade.

The borehole's still for sale, btw; buyer collect.

On 7 Nov,
"dennis@home" wrote:

That's not actually true.. you can't exceed ~10m, at that point the water
will break into a vacuum in the pipe and no water can ever pass using a
siphon.
Its the reason why wells have to have the pump at the bottom, you just
can't "suck" water up any higher.

If the header tank is higher than the top of the n then it wouldn't be below
atmospheric there. You could go up a further 20 feet or so (32 in theory) but
only with cold water. With water at CH temperatures then no higher than the
header tank. This assumes the air can be removed from the pipe. With a sealed
system then a larger n could be sustained.

However, it's not a good idea to go up and down if it can be avoided.

I'd guess in OP's case, an airlock. But if not it could be excessive pipe
length, but then I'd expect some trace of heat.

--
B Thumbs
Change lycos to yahoo to reply

On 7 Nov,
(Alan Braggins) wrote:

In article , Jules Richardson wrote:
On Mon, 07 Nov 2011 09:09:36 +0000, dennis@home wrote:
Its the reason why wells have to have the pump at the bottom, you just
can't "suck" water up any higher.

Agreed on the sucking aspect, but just to point out that a well doesn't
have to have the pump at the bottom - mine's approx 86 feet deep with a
surface-mounted jet pump (I'm not sure if there's a practical limit at
which point a jet pump is no good and a submersible pump *has* to be
used, however).

http://www.popularmechanics.com/home...umbing/1275136
reckons "several hundred feet". But part of the pump mechanism is down the
well even if the main pump is on the surface, you can't suck it up from
above that far.

A lift of about 22 feet is about the practical limit. I assume the jet pump
is some form of venturi down the well, with a surface pressure pump to it. An
air injecter is another method of exceeding the 32 foot (theoretical) limit.

--
B Thumbs
Change lycos to yahoo to reply

On 08/11/2011 23:12, wrote:
On 7 Nov,
(Alan Braggins) wrote:

In , Jules Richardson wrote:
On Mon, 07 Nov 2011 09:09:36 +0000, dennis@home wrote:
Its the reason why wells have to have the pump at the bottom, you just
can't "suck" water up any higher.

Agreed on the sucking aspect, but just to point out that a well doesn't
have to have the pump at the bottom - mine's approx 86 feet deep with a
surface-mounted jet pump (I'm not sure if there's a practical limit at
which point a jet pump is no good and a submersible pump *has* to be
used, however).

http://www.popularmechanics.com/home...umbing/1275136
reckons "several hundred feet". But part of the pump mechanism is down the
well even if the main pump is on the surface, you can't suck it up from
above that far.

A lift of about 22 feet is about the practical limit. I assume the jet pump
is some form of venturi down the well, with a surface pressure pump to it. An
air injecter is another method of exceeding the 32 foot (theoretical) limit.



......and back to the original problem!

I have shut down all other radiators and left the pump running. No
effect. Again, if I remove the bleed valve, I get warm water through,
so the supply side is OK.

To try and resolve this, I plan to fit an automatic bleed valve. I
can't do it at the highest point as the pipes are against the ceiling,is
there any reason why I can't do it on one of the verticals as high as
possible?

Cheers

Peter