Dave wrote:
I have an oil-fired central heating system. Most radiators are either
luke warm, or cold. One or two are hot.

The house is on two level. The system consists of

* Oil boiler
* Water pump
* About 15 radiators on two level.
* Each radiator has two valves - one user adjustable, and the other
which requires a spanner to adjust.
* Two drain points, both on the lower level.
* Presurised system
* A 'tank' of some sort, although I don't think it is a tank. I believe
there is some sort of membrane in it, which expands/contracts with water
pressure. It has a bleed screw on the top (just like radiators) and also
a much larger screw which I have no undone. I'm wondering if this might
be sensible to do.

As far as I am aware, the radiators are arranged in a series/parallel
arrangement. i.e perhaps 5 are in series, then another 5 in series, then
another 5 in series, but the groups of 5 are in parallel. This is what
the plumber who fitted this said, although I have no idea of the exact
arrangement. (He is now dead, so no chance of asking him)

The pump was making a funny noise. Hard to describe, but no usual sound.
I thought the pump was faulty, so replaced the pump, but it made no
difference.

All the radiators have been bled, although perhaps not correctly. For
example. Is there any set order - for example do upstairs, then down? As
I open the bleed screw, each lets out water, with no hissing sound
suggesting air is coming out.

Two radiators upstairs are getting hot. Most others are luke warm at best.

I am aware of a couple of radiators which has slight leaks. Perhaps air
is entering there? I can't see how air can enter a pressurised system,
but I believe I have read it can.


What I find odd is that some radiators have clear water when I open
them, and others seem to have different colour liquids. I don't believe
the water is circulating properly.

Any ideas what I can do to sort the problem out?

x-posted to uk.d-i-y where people who know more than me hang out.

Andy

On Mon, 22 Sep 2008 20:21:03 +0100, Andy Champ wrote:

Any ideas what I can do to sort the problem out?

x-posted to uk.d-i-y where people who know more than me hang out.

You could read this and see if it helps:
http://wiki.diyfaq.org.uk/index.php?...Heating_Repair

(And if it doesn't you come back here and say what we need to put in so it
does help!)

--
YAPH http://yaph.co.uk

You'll make some woman a fine husband, Dr Frankenstein

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

Dave wrote:
I have an oil-fired central heating system. Most radiators are either
luke warm, or cold. One or two are hot.

The house is on two level. The system consists of

* Oil boiler
* Water pump
* About 15 radiators on two level.
* Each radiator has two valves - one user adjustable, and the other
which requires a spanner to adjust.
* Two drain points, both on the lower level.
* Presurised system
* A 'tank' of some sort, although I don't think it is a tank. I
believe there is some sort of membrane in it, which
expands/contracts with water pressure. It has a bleed screw on the
top (just like radiators) and also a much larger screw which I have
no undone. I'm wondering if this might be sensible to do.

That will almost certainly be the pressure vessel - which has air on one
side of the diaphragm and water on the other, and allows the water to expand
when it gets hot. There will also be a filling loop to enable the water
system to be topped up, and a pressure gauge which shows how much pressure
there in the system. What does the gauge read (a) with the system cold and
(b) with it hot? Have you been topping it up after you have bled the
radiators?

As far as I am aware, the radiators are arranged in a series/parallel
arrangement. i.e perhaps 5 are in series, then another 5 in series,
then another 5 in series, but the groups of 5 are in parallel. This
is what the plumber who fitted this said, although I have no idea of
the exact arrangement. (He is now dead, so no chance of asking him)

I sincerly hope that it *isn't* a series/parallel arrangement. It's more
likely to be 3 circuits, each with a flow and return pipe going back to a
central point, and with 5 rads in each circuit connected between flow and
return so that - in effect - all 15 are in parallel with each other. You
need to have a close look at the pipework to verify that because it will
affect the way you need to balance the system.

The pump was making a funny noise. Hard to describe, but no usual
sound. I thought the pump was faulty, so replaced the pump, but it
made no difference.

All the radiators have been bled, although perhaps not correctly. For
example. Is there any set order - for example do upstairs, then
down? As I open the bleed screw, each lets out water, with no
hissing sound suggesting air is coming out.

Two radiators upstairs are getting hot. Most others are luke warm at
best.
It sounds to me as if you first need to ensure that there's adequate
pressure in the system and you then need to balance the system to make sure
that all rads gets an equitable share of the available heat. Doubtless Ed
will be along soon and will point you at FAQs about presurised systems and
about how to balance your system

I am aware of a couple of radiators which has slight leaks. Perhaps
air is entering there? I can't see how air can enter a pressurised
system, but I believe I have read it can.


You need to fix the leaks. Even if air does't get in, the system will lose
pressure if there are leaks and will need frequent topping up. Apart from
the inconvenience, this will also dilute any corrosion inhibitor in the
system.

What I find odd is that some radiators have clear water when I open
them, and others seem to have different colour liquids. I don't
believe the water is circulating properly.

Yes, sounds odd - I agree!

Any ideas what I can do to sort the problem out?

See the above comments on pressurising and balancing. You haven't mentioned
any controls which the system may have. Are there any motorised valves and
room/cylinder thermostats etc.? If you could take photos of all the
interesting bits and upload them somewhere and post a link here, that would
be very helpful.
--
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,
Andy Champ wrote:

Dave wrote:
I have an oil-fired central heating system. Most radiators are either
luke warm, or cold. One or two are hot.

The house is on two level. The system consists of

* Oil boiler
* Water pump
* About 15 radiators on two level.
* Each radiator has two valves - one user adjustable, and the other
which requires a spanner to adjust.
* Two drain points, both on the lower level.
* Presurised system
* A 'tank' of some sort, although I don't think it is a tank. I
believe there is some sort of membrane in it, which
expands/contracts with water pressure. It has a bleed screw on the
top (just like radiators) and also a much larger screw which I have
no undone. I'm wondering if this might be sensible to do.

That will almost certainly be the pressure vessel - which has air on one
side of the diaphragm and water on the other, and allows the water to expand
when it gets hot. There will also be a filling loop to enable the water
system to be topped up, and a pressure gauge which shows how much pressure
there in the system. What does the gauge read (a) with the system cold and
(b) with it hot? Have you been topping it up after you have bled the
radiators?


There is a filling loop, pressure gauge and pressure relief (safety)
valve which blows at 3 bar. The pressure is about 1 bar, and rises a
little when hot.


As far as I am aware, the radiators are arranged in a series/parallel
arrangement. i.e perhaps 5 are in series, then another 5 in series,
then another 5 in series, but the groups of 5 are in parallel. This
is what the plumber who fitted this said, although I have no idea of
the exact arrangement. (He is now dead, so no chance of asking him)

I sincerly hope that it *isn't* a series/parallel arrangement. It's more
likely to be 3 circuits, each with a flow and return pipe going back to a
central point, and with 5 rads in each circuit connected between flow and
return so that - in effect - all 15 are in parallel with each other. You
need to have a close look at the pipework to verify that because it will
affect the way you need to balance the system.


This is difficult to do, as the pipes go into the space between upstairs
and downstairs, so unless I took up loads of floorboards, it would be
difficult to know.

I know there are two pipes running close to each other which go from
upstairs to down at the centre of the house, and another two to one side
of the house. Hence there are 4 pipes connecting upstairs to downstairs.

I can't say the plumber used the term series/parallel. That is what I
interpreted it as - I'm an electronics engineer.

The pump was making a funny noise. Hard to describe, but no usual
sound. I thought the pump was faulty, so replaced the pump, but it
made no difference.

All the radiators have been bled, although perhaps not correctly. For
example. Is there any set order - for example do upstairs, then
down? As I open the bleed screw, each lets out water, with no
hissing sound suggesting air is coming out.

Two radiators upstairs are getting hot. Most others are luke warm at
best.
It sounds to me as if you first need to ensure that there's adequate
pressure in the system and you then need to balance the system to make sure
that all rads gets an equitable share of the available heat. Doubtless Ed
will be along soon and will point you at FAQs about presurised systems and
about how to balance your system


There is adequate pressure. I was told 1 bar, and it is about that. As I
said, there are a couple of very small leaks which necessitate topping
this up every few months. I will fix them this week.

I suspect balancing would be useful. Some have always seemed to be
hotter than others, but in some ways that is quite useful, as one room
in particular seemed to me it needs a bit more heating, whereas other
areas less.


I am aware of a couple of radiators which has slight leaks. Perhaps
air is entering there? I can't see how air can enter a pressurised
system, but I believe I have read it can.


You need to fix the leaks. Even if air does't get in, the system will lose
pressure if there are leaks and will need frequent topping up. Apart from
the inconvenience, this will also dilute any corrosion inhibitor in the
system.

I appreciate that, and will do so. I was hoping to get the bits today,
but had a lot of weight in the car (stones) and so did not wish to drive
a longer journey than necessary.


What I find odd is that some radiators have clear water when I open
them, and others seem to have different colour liquids. I don't
believe the water is circulating properly.

Yes, sounds odd - I agree!


Any ideas what I can do to sort the problem out?
See the above comments on pressurising and balancing. You haven't mentioned
any controls which the system may have. Are there any motorised valves and
room/cylinder thermostats etc.? If you could take photos of all the
interesting bits and upload them somewhere and post a link here, that would
be very helpful.

There are no motorised valves, but there are some thermostatic valves.
The latter have been quite unreliable - the usual problem is the plastic
becomes brittle over time, then they break off. As they have tended to
develop faults, I've normally not bothered replacing them and instead
replaced them with manual controls.


The radiators have a vertical pin on one one end, which controls the
water flow. It is between around the pin that a couple of leaks have
developed. I hope these are easy to replace, and not specific to a
particular radiator type. The pipe has an OD of 15 mm at the radiators,
although some is thicker elsewhere - I think 22mm.

If that is not a sufficient description, I'll take photos later.

I assume that since I need to drain the system to fix the leaks on the
valves, it would be sensible to flush the system with a cleaner before
adding fresh water and corrosion inhibitor.

Dave

In an earlier contribution to this discussion,
Dave wrote:



There is a filling loop, pressure gauge and pressure relief (safety)
valve which blows at 3 bar. The pressure is about 1 bar, and rises a
little when hot.

That sounds ok.



This is difficult to do, as the pipes go into the space between
upstairs and downstairs, so unless I took up loads of floorboards, it
would be difficult to know.

I know there are two pipes running close to each other which go from
upstairs to down at the centre of the house, and another two to one
side of the house. Hence there are 4 pipes connecting upstairs to
downstairs.
Does the boiler also heat a cylinder full of hot water (I assume it's not a
combi)? If so, 2 of the pipes could be for a HW circuit between boiler and
airing cupboard.

I can't say the plumber used the term series/parallel. That is what I
interpreted it as - I'm an electronics engineer.

The usual arrangement is to connect one side of each rad to the flow pipe
and the other side to the return pipe. The electrical analogy is several
resistors connected in parallel between +ve and -ve. To continue the
analogy, you might have a trimming resistor (analogous to a lockshield
valve) in series with each resistor to allow the current (water flow) to be
balanced across all sub-circuits.



There is adequate pressure. I was told 1 bar, and it is about that.
As I said, there are a couple of very small leaks which necessitate
topping this up every few months. I will fix them this week.

It it literally only needs topping up every few months, fixing the leaks is
not that much of a priority - I'd get it working properly first.

I suspect balancing would be useful. Some have always seemed to be
hotter than others, but in some ways that is quite useful, as one room
in particular seemed to me it needs a bit more heating, whereas other
areas less.

Are the radiators hot all over? If so, balancing would be a good start. If
there's a cold pyramid shaped patch at the bottom, it could be that they're
sludged up and need flushing.



There are no motorised valves, but there are some thermostatic valves.
The latter have been quite unreliable - the usual problem is the
plastic becomes brittle over time, then they break off. As they have
tended to develop faults, I've normally not bothered replacing them
and instead replaced them with manual controls.

The radiators have a vertical pin on one one end, which controls the
water flow. It is between around the pin that a couple of leaks have
developed. I hope these are easy to replace, and not specific to a
particular radiator type. The pipe has an OD of 15 mm at the
radiators, although some is thicker elsewhere - I think 22mm.

I presume that you're referring to the pins in the thermostatic valves - in
which case they're not part of the radiator per se, but a separate
replaceable component? The thermostatic part of the valve (the
plastic-enclosed capsule on the top) moves the pin up and down to shut off
the flow when the room is hot enough. These pins can sometimes stick in the
closed or partially open position - which may perhaps explain some of your
symptoms. With the capsule removed. you should be able to push the pin down
against a spring - and it should pop up again when released. If it doesn't
do this, get a couple of small hammers and simultaneously tap both sides of
the valve lightly to see whether you can free it.

If that is not a sufficient description, I'll take photos later.

If there are no controls other than TRVs, it's probably not worth it.

I assume that since I need to drain the system to fix the leaks on the
valves, it would be sensible to flush the system with a cleaner before
adding fresh water and corrosion inhibitor.


Unless it's obviously sludged up I'd try to balance it before ripping it
apart, having first made sure that the pins in the TRVs are free.

To do a proper balance, you need an infra-red thermometer so that you can
quickly measure the flow and return temperature of each rad - but you can do
a crude balance simply by feeling the rads and progressively turning down
the lockshields on the hottest ones until they all feel more or less the
same.
--
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,
Dave wrote:


There is a filling loop, pressure gauge and pressure relief (safety)
valve which blows at 3 bar. The pressure is about 1 bar, and rises a
little when hot.

That sounds ok.


This is difficult to do, as the pipes go into the space between
upstairs and downstairs, so unless I took up loads of floorboards, it
would be difficult to know.

I know there are two pipes running close to each other which go from
upstairs to down at the centre of the house, and another two to one
side of the house. Hence there are 4 pipes connecting upstairs to
downstairs.
Does the boiler also heat a cylinder full of hot water (I assume it's not a
combi)? If so, 2 of the pipes could be for a HW circuit between boiler and
airing cupboard.

No, the oil boiler does not heat a tank of hot water.

Hot water heating is done via electric, not oil. The reason this was
done (despite electricity being much more expensive per kW hr than oil),
is that there is a wood burning stove too. That wood burning stove heats
the hot water too - in addition to the electric, although the wood
burner is rarely used. The plumber who fitted the oil central heating
said it would be unsafe to heat the water in the hot water tank 3 ways -
electric, wood and oil. So the hot water remains heated by electric +
wood only.

Hence I assume this means there are two circuits upstairs? I've just
counted the radiators and find there is 5 upstairs and 6 radiators
downstairs - it's a 3 bedroom detached house.


I can't say the plumber used the term series/parallel. That is what I
interpreted it as - I'm an electronics engineer.

The usual arrangement is to connect one side of each rad to the flow pipe
and the other side to the return pipe. The electrical analogy is several
resistors connected in parallel between +ve and -ve. To continue the
analogy, you might have a trimming resistor (analogous to a lockshield
valve) in series with each resistor to allow the current (water flow) to be
balanced across all sub-circuits.

I'm not aware of any control which trims individual circuits.

There is adequate pressure. I was told 1 bar, and it is about that.
As I said, there are a couple of very small leaks which necessitate
topping this up every few months. I will fix them this week.

It it literally only needs topping up every few months, fixing the leaks is
not that much of a priority - I'd get it working properly first.

I think I should fix these, as some of the leaks are more serious if the
control on the rad is not screwed down fully. If the manual control is
not screwed down fully but removed, water can be clearly seen coming
around the pin on two or three of these. Hence I can't really use these
rads at all.

I suspect balancing would be useful. Some have always seemed to be
hotter than others, but in some ways that is quite useful, as one room
in particular seemed to me it needs a bit more heating, whereas other
areas less.

Are the radiators hot all over? If so, balancing would be a good start. If
there's a cold pyramid shaped patch at the bottom, it could be that they're
sludged up and need flushing.

I'll have to check for any pyramid shape region of hot. Some seem almost
cold to me, but I'll have to double check.

I've tended to notice that neither pipe at the bottom of some rads is
warm. I'll double check this later. The heating is not on at this
minute, as the weather here is quite mild. If the rad has been switched
off for some hours, would you expect both pipes at the bottom to be
cold? I assume if no water flows through the rad, then eventually the
pipes cool. If that is not so, then it might indicate the problem.

One other thing I should have mentioned is that the plumber who fitted
this said one rad should be on all the time. He suggested the one at the
top of the stairs, but we found that just made there far too hot. So I
changed that, but restricting the flow to that one and opening one up
elsewhere. That was down a few years back and worked OK, so that is not
the reason for this problem.

There are no motorised valves, but there are some thermostatic valves.
The latter have been quite unreliable - the usual problem is the
plastic becomes brittle over time, then they break off. As they have
tended to develop faults, I've normally not bothered replacing them
and instead replaced them with manual controls.

The radiators have a vertical pin on one one end, which controls the
water flow. It is between around the pin that a couple of leaks have
developed. I hope these are easy to replace, and not specific to a
particular radiator type. The pipe has an OD of 15 mm at the
radiators, although some is thicker elsewhere - I think 22mm.

I presume that you're referring to the pins in the thermostatic valves - in
which case they're not part of the radiator per se, but a separate
replaceable component? The thermostatic part of the valve (the
plastic-enclosed capsule on the top) moves the pin up and down to shut off
the flow when the room is hot enough. These pins can sometimes stick in the
closed or partially open position - which may perhaps explain some of your
symptoms. With the capsule removed. you should be able to push the pin down
against a spring - and it should pop up again when released. If it doesn't
do this, get a couple of small hammers and simultaneously tap both sides of
the valve lightly to see whether you can free it.


They all move down ok, and come up if pressure is removed, suggesting a
spring is used. I assumed this pin was part of the radiator and the
thermostatic control was bought as an extra and just pushed this up/down
manually. I did not realise this was bought with the thermostatic
controls. (All rads has these fitted when we had the system installed,
but as I say, they have appeared to be more unreliable than I would have
expected).

If that is not a sufficient description, I'll take photos later.

If there are no controls other than TRVs, it's probably not worth it.

OK.

I assume that since I need to drain the system to fix the leaks on the
valves, it would be sensible to flush the system with a cleaner before
adding fresh water and corrosion inhibitor.


Unless it's obviously sludged up I'd try to balance it before ripping it
apart, having first made sure that the pins in the TRVs are free.

To do a proper balance, you need an infra-red thermometer so that you can
quickly measure the flow and return temperature of each rad - but you can do
a crude balance simply by feeling the rads and progressively turning down
the lockshields on the hottest ones until they all feel more or less the
same.

I do happen to have an IR thermometer. It basically plugs into a digital
volt meter and gives 1 mV/deg C - or something like. I thought the area
it views might be too large for a pipe, but perhaps not if held close
enough. I've also got some type K thermocouples and a DVM which has a
temperature mode which can read temperature from these.

In an earlier contribution to this discussion,
Dave wrote:


Hot water heating is done via electric, not oil. The reason this was
done (despite electricity being much more expensive per kW hr than
oil), is that there is a wood burning stove too. That wood burning
stove heats the hot water too - in addition to the electric, although
the wood burner is rarely used. The plumber who fitted the oil
central heating said it would be unsafe to heat the water in the hot
water tank 3 ways - electric, wood and oil. So the hot water remains
heated by electric + wood only.

Hence I assume this means there are two circuits upstairs? I've just
counted the radiators and find there is 5 upstairs and 6 radiators
downstairs - it's a 3 bedroom detached house.

Are you sure that one pair of pipes doesn't connect the wood-burning stove
to the hot cylinder?


I'm not aware of any control which trims individual circuits.

A lockshield valve on a radiator does just that - see below.


I think I should fix these, as some of the leaks are more serious if
the control on the rad is not screwed down fully. If the manual
control is not screwed down fully but removed, water can be clearly
seen coming around the pin on two or three of these. Hence I can't
really use these rads at all.

In that case, yes! There's no point in having radiators which have to be
turned off to stop them leaking.


I'll have to check for any pyramid shape region of hot. Some seem
almost cold to me, but I'll have to double check.

It's a triangular *cold* patch you need to look for - quite wide at bottom
centre and getting narrower highter up.

I've tended to notice that neither pipe at the bottom of some rads is
warm. I'll double check this later. The heating is not on at this
minute, as the weather here is quite mild. If the rad has been
switched off for some hours, would you expect both pipes at the
bottom to be cold? I assume if no water flows through the rad, then
eventually the pipes cool. If that is not so, then it might indicate
the problem.
If there's no flow through a rad, neither pipe will be warm.



They all move down ok, and come up if pressure is removed, suggesting
a spring is used. I assumed this pin was part of the radiator and the
thermostatic control was bought as an extra and just pushed this
up/down manually. I did not realise this was bought with the
thermostatic controls. (All rads has these fitted when we had the
system installed, but as I say, they have appeared to be more
unreliable than I would have expected).

When you buy a radiator, you get *just* a radiator - looking something like
http://tinyurl.com/3lbrvc with 2 or 4 tapped holes at the corners. In order
to connect the pipes, you need valves which screw into two of the tapped
holes. [If there are 4 holes, the 3rd one has a blanking plug and the 4th a
bleed screw]. If you are controlling the radiators thermostatically - as you
appear to be - one of the valves will be a TRV, something like
http://tinyurl.com/53jgs2 and the other will be a lockshield valve,
something like http://tinyurl.com/47uox8 (when fitted with the plain cover
shown, rather than the handwheel)
The TRV has a pin inside which is pushed up and down by the thermostatic
capsule and stops the flow when the room is warm enough. The lockshield is
turned on and off by rotating its spindle with a spanner, and has to be
adjusted to a part-open state (and then left alone) when balancing the flow.


I do happen to have an IR thermometer. It basically plugs into a
digital volt meter and gives 1 mV/deg C - or something like. I
thought the area it views might be too large for a pipe, but perhaps
not if held close enough. I've also got some type K thermocouples and
a DVM which has a temperature mode which can read temperature from
these.

What you've got *may* be ok - but you really need an all-in-one hand-held
device such as http://tinyurl.com/4tbcop which enables you to zoom round the
system and measure the flow and return temp of each rad in a few seconds
each.
--
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!

Dave wrote:

I think I should fix these, as some of the leaks are more serious if the
control on the rad is not screwed down fully. If the manual control is
not screwed down fully but removed, water can be clearly seen coming
around the pin on two or three of these. Hence I can't really use these
rads at all.


Hang on a minute - if this is a full series system, or if part of it is,
won't turning off one rad in the series part turn off all the rads in
that part of the circuit? (Equivalent to turning off a switch in a
series circuit)

Turn all the TRVs up high (with suitable placement of sponges/cloths as
necessary ) and see what happens.

Andy

symptoms. With the capsule removed. you should be able to push the pin
down against a spring - and it should pop up again when released. If it
doesn't do this, get a couple of small hammers and simultaneously tap
both sides of the valve lightly to see whether you can free it.


They all move down ok, and come up if pressure is removed, suggesting a
spring is used.

Try actually pulling the pin up, I had a problem with thermostatic valves
sticking when we first moved into our current house. I put it down to the
valves not being used for the year the house was empty. After pulling them
up and pushing them back down a few times, plus a bit of WD40 they all
worked OK. One did leak but only when the pin was part way up, it had to be
replaced of course because in normal use it is often part way up.

Mike

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

Dave wrote:

I think I should fix these, as some of the leaks are more serious if
the control on the rad is not screwed down fully. If the manual
control is not screwed down fully but removed, water can be clearly
seen coming around the pin on two or three of these. Hence I can't
really use these rads at all.


Hang on a minute - if this is a full series system, or if part of it
is, won't turning off one rad in the series part turn off all the
rads in that part of the circuit? (Equivalent to turning off a
switch in a series circuit)

Yes indeed, if the rads are *truly* in series, turning one off will stop the
flow through *all* of those in that group.

But I'm far from convinced (from the OP's description) that they *are* in
series.
--
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,
Dave wrote:

Hot water heating is done via electric, not oil. The reason this was
done (despite electricity being much more expensive per kW hr than
oil), is that there is a wood burning stove too. That wood burning
stove heats the hot water too - in addition to the electric, although
the wood burner is rarely used. The plumber who fitted the oil
central heating said it would be unsafe to heat the water in the hot
water tank 3 ways - electric, wood and oil. So the hot water remains
heated by electric + wood only.

Hence I assume this means there are two circuits upstairs? I've just
counted the radiators and find there is 5 upstairs and 6 radiators
downstairs - it's a 3 bedroom detached house.

Are you sure that one pair of pipes doesn't connect the wood-burning stove
to the hot cylinder?


Yes, I am sure. The wood burning stove was there many years before the
oil. The two pair of pipes were added when the oil heating was installed.


I'm not aware of any control which trims individual circuits.

A lockshield valve on a radiator does just that - see below.

Got you. All rads have these - most only have one, but one rad has two.
The one that was supposed to be left on all the time.


I think I should fix these, as some of the leaks are more serious if
the control on the rad is not screwed down fully. If the manual
control is not screwed down fully but removed, water can be clearly
seen coming around the pin on two or three of these. Hence I can't
really use these rads at all.

In that case, yes! There's no point in having radiators which have to be
turned off to stop them leaking.

Agreed. I'm a bit pushed for time this week, as I have to finish a
gardening job, before some materials are delivered.


I'll have to check for any pyramid shape region of hot. Some seem
almost cold to me, but I'll have to double check.

It's a triangular *cold* patch you need to look for - quite wide at bottom
centre and getting narrower highter up.

OK, I'll check that.

I've tended to notice that neither pipe at the bottom of some rads is
warm. I'll double check this later. The heating is not on at this
minute, as the weather here is quite mild. If the rad has been
switched off for some hours, would you expect both pipes at the
bottom to be cold? I assume if no water flows through the rad, then
eventually the pipes cool. If that is not so, then it might indicate
the problem.
If there's no flow through a rad, neither pipe will be warm.

I thought that might be the case.


They all move down ok, and come up if pressure is removed, suggesting
a spring is used. I assumed this pin was part of the radiator and the
thermostatic control was bought as an extra and just pushed this
up/down manually. I did not realise this was bought with the
thermostatic controls. (All rads has these fitted when we had the
system installed, but as I say, they have appeared to be more
unreliable than I would have expected).

When you buy a radiator, you get *just* a radiator - looking something like
http://tinyurl.com/3lbrvc with 2 or 4 tapped holes at the corners. In order
to connect the pipes, you need valves which screw into two of the tapped
holes. [If there are 4 holes, the 3rd one has a blanking plug and the 4th a
bleed screw]. If you are controlling the radiators thermostatically - as you
appear to be - one of the valves will be a TRV, something like
http://tinyurl.com/53jgs2 and the other will be a lockshield valve,
something like http://tinyurl.com/47uox8 (when fitted with the plain cover
shown, rather than the handwheel)
The TRV has a pin inside which is pushed up and down by the thermostatic
capsule and stops the flow when the room is warm enough. The lockshield is
turned on and off by rotating its spindle with a spanner, and has to be
adjusted to a part-open state (and then left alone) when balancing the flow.


I understand now. I have a better idea of what I have and need.

I do happen to have an IR thermometer. It basically plugs into a
digital volt meter and gives 1 mV/deg C - or something like. I
thought the area it views might be too large for a pipe, but perhaps
not if held close enough. I've also got some type K thermocouples and
a DVM which has a temperature mode which can read temperature from
these.

What you've got *may* be ok - but you really need an all-in-one hand-held
device such as http://tinyurl.com/4tbcop which enables you to zoom round the
system and measure the flow and return temp of each rad in a few seconds
each.



That link just goes to a Maplin home page, with no device, so I don't
know what you mean. Can you give me a Maplin part number?

In an earlier contribution to this discussion,
Dave wrote:


That link just goes to a Maplin home page, with no device, so I don't
know what you mean. Can you give me a Maplin part number?

Sorry, it was a link from one their special offer emails which *used* to go
straight to the item but now goes to the main page - so perhaps they've run
out. The part number was N92FX but I can't find it on their site any more.

Alternatively, I've got one of these
http://cpc.farnell.com/IN02293/test-...nbranded-ir-88
which does the job admirably.
--
Cheers,
Roger
______
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In an earlier contribution to this discussion,
Roger Mills wrote:

In an earlier contribution to this discussion,
Dave wrote:


That link just goes to a Maplin home page, with no device, so I don't
know what you mean. Can you give me a Maplin part number?

Sorry, it was a link from one their special offer emails which *used*
to go straight to the item but now goes to the main page - so perhaps
they've run out. The part number was N92FX but I can't find it on
their site any more.
Alternatively, I've got one of these
http://cpc.farnell.com/IN02293/test-...nbranded-ir-88
which does the job admirably.


Maplin have got a slightly different one - N93FX - amongst today's bargain
offerings.
--
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,
Dave wrote:

That link just goes to a Maplin home page, with no device, so I don't
know what you mean. Can you give me a Maplin part number?

Sorry, it was a link from one their special offer emails which *used* to go
straight to the item but now goes to the main page - so perhaps they've run
out. The part number was N92FX but I can't find it on their site any more.

Alternatively, I've got one of these
http://cpc.farnell.com/IN02293/test-...nbranded-ir-88
which does the job admirably.


Thank you. I note at 8cm distance from the object, the Farnell one view
s 1 cm. Also the same with the Maplin one you posted later. I'll check
what my IR thermometer is. Assuming mine views the same sort of range, I
might as well use that and save myself a few pounds. It came from RS
originally, but I can't find the exact same part on the RS web site. It
basically takes a PP3 battery and outputs the signal to a DVM. Mine does
not have a laser pointer in it, but it should be pretty obvious from the
output voltage if its pointing at a hot pipe when there is nothing else
around it that is hot.

One problem I has is that the boiler is switching off quite quickly. I
think the flow around the system is too small, so the boiler shuts off.
Of course this could be a boiler fault, but the fact the pump was making
a strange noise led me to believe that was probably not so.

I assume the boiler shuts off when the input temperature is above some
preset value. There is a control on the boiler, but it is marked 1, 2,
3, 4, 5 rather than any numerical value. I can check the manual for the
oil boiler and see if that indicates when it should shut off.

I'll order some TRVs, as I have at least 4 which are showing some signs
of failure - usually the plastic becomes brittle, then the top snaps off
.. Is there any one make you would consider better than others? I noted
that they seem to be available from about £7 to £90, with most in the
range £7 to £15. Cost is not really an issue, but I'm fed up with the
things going wrong. I was in fact warned their reliability was not
great, but the failure rate seems to be higher than I would have
expected. I think the ones I have are made by Honeywell.

Once I've got the new TRVs, I'll flush the system and try to balance it.
One problem I have here is that since I don't know the ordering of the
radiators, it will be difficult to adjust them in the order starting at
those closes to the boiler. I'll have to take a best guess on this I think.

In an earlier contribution to this discussion,
Dave wrote:


One problem I has is that the boiler is switching off quite quickly. I
think the flow around the system is too small, so the boiler shuts
off. Of course this could be a boiler fault, but the fact the pump was
making a strange noise led me to believe that was probably not so.

I assume the boiler shuts off when the input temperature is above some
preset value. There is a control on the boiler, but it is marked 1, 2,
3, 4, 5 rather than any numerical value. I can check the manual for
the oil boiler and see if that indicates when it should shut off.

I assume that the boiler stat controls the *output* temperature - which you
can measure with your IR thermometer! Aim at about 80 degC. If the system is
not absorbing the full boiler output, the boiler will cycle on its stat.
This is quite normal. It doesn't matter if the flow temperature fluctuates a
*bit* during balancing because you will be measuring both sides of each rad
and determining the *drop*. It's important to keep the pump running all the
time.

I'll order some TRVs, as I have at least 4 which are showing some
signs of failure - usually the plastic becomes brittle, then the top snaps
off . Is there any one make you would consider better than others? I
noted that they seem to be available from about £7 to £90, with most
in the range £7 to £15. Cost is not really an issue, but I'm fed up
with the things going wrong. I was in fact warned their reliability
was not great, but the failure rate seems to be higher than I would have
expected. I think the ones I have are made by Honeywell.

The valves with probably the best reputation are Drayton TRV4's. You'll pay
silly prices in the High Street but can get them at sensible prices on Ebay.

Once I've got the new TRVs, I'll flush the system and try to balance
it. One problem I have here is that since I don't know the ordering
of the radiators, it will be difficult to adjust them in the order
starting at those closes to the boiler. I'll have to take a best
guess on this I think.

Don't worry about that - it's not the way I do it, anyway. Start with all
lockshields fully open and then turn down the lockshields on the rads which
have the *lowest* temperature drop regardless of their proximity to the
boiler. This will restrict the flow on these rads and force more water
through the cooler rads. It's an iterative processes, and you keep going
round until you get more or less the same drop on all rads. Then you look at
the *actual* drop - which ideally should be 10 or 11 decC. If it's
significantly more, you need to increase the pump speed and if significantly
less, decrease the pump speed (assuming it's adjustable!) - and then recheck
the balance.
--
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,
Dave wrote:

One problem I has is that the boiler is switching off quite quickly. I
think the flow around the system is too small, so the boiler shuts
off. Of course this could be a boiler fault, but the fact the pump was
making a strange noise led me to believe that was probably not so.

I assume the boiler shuts off when the input temperature is above some
preset value. There is a control on the boiler, but it is marked 1, 2,
3, 4, 5 rather than any numerical value. I can check the manual for
the oil boiler and see if that indicates when it should shut off.

I assume that the boiler stat controls the *output* temperature - which you
can measure with your IR thermometer! Aim at about 80 degC. If the system is
not absorbing the full boiler output, the boiler will cycle on its stat.
This is quite normal. It doesn't matter if the flow temperature fluctuates a
*bit* during balancing because you will be measuring both sides of each rad
and determining the *drop*. It's important to keep the pump running all the
time.

Thank you. I'll check this after I've replaced the TRVs.


I'll order some TRVs, as I have at least 4 which are showing some
signs of failure - usually the plastic becomes brittle, then the top snaps
off . Is there any one make you would consider better than others? I
noted that they seem to be available from about £7 to £90, with most
in the range £7 to £15. Cost is not really an issue, but I'm fed up
with the things going wrong. I was in fact warned their reliability
was not great, but the failure rate seems to be higher than I would have
expected. I think the ones I have are made by Honeywell.

The valves with probably the best reputation are Drayton TRV4's. You'll pay
silly prices in the High Street but can get them at sensible prices on Ebay.

Thank you. I followed your advice and ordered 4 from eBay at £47
including carriage, so about £12 each.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=380062531138


Once I've got the new TRVs, I'll flush the system and try to balance
it. One problem I have here is that since I don't know the ordering
of the radiators, it will be difficult to adjust them in the order
starting at those closes to the boiler. I'll have to take a best
guess on this I think.

Don't worry about that - it's not the way I do it, anyway. Start with all
lockshields fully open and then turn down the lockshields on the rads which
have the *lowest* temperature drop regardless of their proximity to the
boiler. This will restrict the flow on these rads and force more water
through the cooler rads. It's an iterative processes, and you keep going
round until you get more or less the same drop on all rads. Then you look at
the *actual* drop - which ideally should be 10 or 11 decC. If it's
significantly more, you need to increase the pump speed and if significantly
less, decrease the pump speed (assuming it's adjustable!) - and then recheck
the balance.

Thank you, that makes a lot of sence. How long does it typically take
for the termperature to stabilise so they can be adjusted again? I can
imagine this might be a very long process. Would you have the pump at
maximum flow rate initially to speed the process up?

The pump I have has 3 speeds. What is the reason for running it at a
reduced speed? It would seem to me that the system will respond quicker
if the flow rate is highest. Although I guess it wears the pump out faster.

Dave

In an earlier contribution to this discussion,
Dave wrote:


Thank you, that makes a lot of sence. How long does it typically take
for the termperature to stabilise so they can be adjusted again? I can
imagine this might be a very long process. Would you have the pump at
maximum flow rate initially to speed the process up?

It's one of those things you have to 'play by ear'. Typically you'll
probably need to wait about 10 minutes after making adjustments before going
round and measuring all the rad temperatures again.

The pump I have has 3 speeds. What is the reason for running it at a
reduced speed? It would seem to me that the system will respond
quicker if the flow rate is highest. Although I guess it wears the pump
out
faster.

The faster the pump goes, the more electricty it uses and the more water
noise you get. So, in general, you want to run it as *slowly* as you can,
consistent with not having too high a drop between flow and return
temperatures.

I think I would initially use the middle speed for balancing. If you run it
too fast it will reduce the temperature drop, and may tend to mask the
difference between the hotter and cooler rads, making balancing more
difficult.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
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